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1.
Med Sci Law ; 63(4): 272-279, 2023 Oct.
Article in English | MEDLINE | ID: mdl-36448196

ABSTRACT

Older adults are the fastest growing sub-group in prisons. They have complex health, social care and custodial needs and often the support they receive is sub-optimal. The Older prisoner Health and Social Care Assessment and Plan (OHSCAP) aimed to better meet these inter-related needs. As part of a wider study, a randomised controlled trial was conducted to evaluate the OHSCAPs effectiveness in meeting older prisoners' health, social care and custodial needs in comparison to treatment as usual. This article describes the nested qualitative study which aimed to explore the barriers and facilitators to the effective implementation of the OHSCAP. Semi-structured interviews were conducted with older adults (n = 14) and staff members t (n = 12). Data was analysed using the framework method. Three overarching key themes were identified. These were: (1) balancing care and custodial requirements; (2) prison, health and social care silos; and (3) rigid prison processes. Prison is an important opportunity to engage residents and improve public health. Cultural and strategic change is required for health, social care and custodial interventions, such as the OHSCAP, to be successfully implemented into prison settings.


Subject(s)
Prisoners , Humans , Aged , Prisons , Qualitative Research , Public Health
3.
Allergol Immunopathol (Madr) ; 45(4): 325-332, 2017.
Article in English | MEDLINE | ID: mdl-27889334

ABSTRACT

OBJECTIVE: Infants are born immunologically immature. However, breastfeeding mothers retain an immunological link to their infants. While it is generally accepted that infants are at an immunological advantage when compared with formula-fed infants, the benefit of long-term exclusive breastfeeding by atopic mothers remains controversial. Inconsistency in the conferral of benefit may be due to differences in the immunological constituents passed to the recipient infant. The aim of this investigation was to examine the profile of human milk cells and cytokines from asthmatic compared to non-asthmatic mothers. METHODS: Twenty-five exclusively breastfeeding mothers with a clinical diagnosis of asthma were postpartum age matched in a double-control 2:1 design with 50 non-asthmatic controls. Each mother provided a single milk sample which was assayed for cell differential by flow cytometry, for ex vivo cytokine production in culture and for aqueous phase cytokines. RESULTS: Milks from asthmatic mothers differed from non-asthmatics in that they contained a higher proportion of polymorphonuclear (PMN) cells and lower proportion of lymphocytes, predominantly CD3+/CD4+ T helper cells, reflected by a decrease in the chemokine CCL5 in the milk aqueous phase. More PMN and lymphocytes from asthmatic mothers expressed the adhesion molecule CD11b and lymphocytes the IgE receptor CD23, than those from non-asthmatic mothers. CONCLUSIONS: Changes to human milk leucocyte prevalence, activation state and cytokines due to maternal asthma may result in changes to immunological priming in the infant. Consequently, the protective effect of long-term breastfeeding may be altered in these mother-infant pairs.


Subject(s)
Asthma/immunology , CD4-Positive T-Lymphocytes/immunology , Chemokine CCL5/metabolism , Milk, Human/immunology , Neutrophils/immunology , Adolescent , Adult , Breast Feeding , CD11b Antigen/metabolism , Cell Count , Cells, Cultured , Female , Humans , Immunity, Maternally-Acquired , Immunization , Mothers , Receptors, IgE/metabolism , Young Adult
4.
Clin Exp Allergy ; 46(7): 1004-14, 2016 07.
Article in English | MEDLINE | ID: mdl-27079163

ABSTRACT

BACKGROUND: Current peanut oral immunotherapy is hampered by frequent adverse events. It has been shown that boiling can reduce peanut allergenicity. Hypoallergenic peanut products have the potential to reduce treatment-related reactions during desensitization. OBJECTIVE: To show that extended boiling (for up to 12 h) can progressively reduce peanut allergenicity while retaining T cell reactivity. METHODS: Raw peanuts were boiled for half, 1, 2, 4 and 12 h in deionized water. After dehydration, boiled and raw peanuts were ground, defatted and soluble proteins extracted in PBS and cooking water (leachate) retained. SDS-PAGE, Western blot, inhibition ELISA, mass spectrometry and skin prick test were used to characterize changes to peanut allergens and human IgE reactivity. T cell responses to raw and boiled peanut extracts were determined by proliferation of CD4+/CD25+/CD134+ T cells in peanut-allergic and non-allergic individuals. RESULTS: Extended boiling progressively reduced peanut allergenicity through a combination of leaching of allergens into cooking water, fragmentation of allergens and denaturation of conformational epitopes. Two-hour boiling led to an eightfold reduction in IgE binding capacity of boiled peanuts as determined by inhibition ELISA, while 12-h boiling led to a 19-fold reduction. Mass spectrometry revealed an increasing number of unique allergen peptides with longer boiling times. Raw, 2- and 12-h boiled peanut extracts were equivalent in their ability to stimulate T cell activation and proliferation. CONCLUSION AND CLINICAL RELEVANCE: Progressive reduction in peanut allergenicity with extended boiling does not affect T cell reactivity. Boiled peanuts may be a candidate for oral immunotherapy.


Subject(s)
Allergens/immunology , Antigens, Plant/immunology , Arachis/immunology , Immunoglobulin E/immunology , Lymphocyte Activation/immunology , Peanut Hypersensitivity/immunology , T-Lymphocytes/immunology , 2S Albumins, Plant/immunology , Amino Acid Sequence , Antigens, Plant/chemistry , Arachis/adverse effects , Cooking , Glycoproteins/immunology , Hot Temperature , Humans , Membrane Proteins , Peanut Hypersensitivity/diagnosis , Peanut Hypersensitivity/metabolism , Peanut Hypersensitivity/therapy , Plant Proteins/immunology , Proteolysis , Skin Tests , T-Lymphocytes/metabolism
5.
Haemophilia ; 22(1): 65-71, 2016 Jan.
Article in English | MEDLINE | ID: mdl-26193989

ABSTRACT

INTRODUCTION: Pain is a major clinical problem in patients with bleeding disorders. This study aimed to determine the level of pain and how it is managed in children and adolescents with bleeding disorders. METHODS: This cross-sectional study was performed in three haemophilia centres (one in Shiraz and two in London).The data were collected using questions about pain management and Wong-Baker Faces Pain Rating Scale at routine clinical review as well as attendance for bleed treatment in summer 2014. RESULTS: This study indicated no difference among the three haemophilia centres regarding having pain, however, a significant difference was found among them concerning the mean score of pain intensity. Among the 154 subjects, 20.8% had pain on the study day, most reporting moderate levels of pain. The study participant's most frequently described their pain as aching, dull, throbbing and stabbing. Moreover, 84.38% of pain was experienced in joints and the most common painful joints were knees, ankles, elbows, hands and hips. The most common pain relief strategies included factor administration, immobilization and rest, ice packs and analgesia. Pain was significantly associated with disease severity and age. CONCLUSION: As the intensity of pain in on-demand patients was highest, using prophylaxis treatment is suggested. Moreover, adolescent patients reported more pain; giving more self-care information to them and their parents is recommended. Since little evidence was published for pain assessment and management in children and adolescents with bleeding disorders, more research is recommended.


Subject(s)
Hemophilia A/complications , Pain Management/statistics & numerical data , Pain Measurement/statistics & numerical data , Pain/complications , Adolescent , Child , Cross-Sectional Studies , Female , Humans , Male
6.
Child Care Health Dev ; 37(3): 422-9, 2011 May.
Article in English | MEDLINE | ID: mdl-21276034

ABSTRACT

BACKGROUND: Parents provide valuable information on their experiences of engaging with therapy services for their children, which can inform the future development of these services. The aim of this study was to explore the views and experiences of parents who had accessed therapy services for their child with developmental co-ordination disorder (DCD). METHODS: Seven focus groups were conducted incorporating 52 parents who had a child diagnosed with, or fitting the diagnostic criteria for DCD. Focus groups were audiotaped, transcribed and analysed thematically. FINDINGS: Parents reported struggling to gain access to therapy services. When they gained access, they found the services beneficial for their child but continued to experience difficulties regarding the quality of service delivery. CONCLUSIONS/IMPLICATIONS: The study suggests that parents thought some health-care professionals lacked knowledge and understanding of DCD, which they believed impacted upon early recognition and access to services. They perceived that therapy at an early age was vital for children's development, and indicated that a clearer path for accessing these services was necessary in addition to improved service quality. They called for an increase in awareness of DCD by all therapy service professionals to aid early recognition and improved treatment.


Subject(s)
Developmental Disabilities/rehabilitation , Health Services Accessibility/organization & administration , Motor Skills Disorders/diagnosis , Parents/psychology , Psychomotor Disorders/rehabilitation , Activities of Daily Living , Adult , Child , Child Development , Developmental Disabilities/physiopathology , Developmental Disabilities/psychology , Evaluation Studies as Topic , Female , Focus Groups , Health Occupations/education , Health Occupations/standards , Humans , Male , Psychomotor Disorders/physiopathology , Psychomotor Disorders/psychology , Stress, Psychological/psychology
8.
Vaccine ; 20(5-6): 641-6, 2001 Dec 12.
Article in English | MEDLINE | ID: mdl-11738728

ABSTRACT

Pertussis vaccination of infants has dramatically reduced disease, complications and deaths in infancy and early childhood. But there is still a major public health challenge--to deal with the morbidity and economic burden of illness in older children, adolescents and adults. Furthermore, it is these groups that form a major source of infection for non-immunised and partially immunised infants who are at high risk of severe complications. Adult-type acellular pertussis vaccine confers safe and effective protection against pertussis. There are several strategies to consider for immunising older individuals. Universal vaccination of all age groups would be the best available strategy for protecting individuals. It would also reduce the potential for transmitting the disease to other susceptibles, particularly infants. However, such a policy may be difficult both logistically and economically at this time. More easily achievable as a first step would be a strategy of universal adolescent booster vaccination combined with a programme targeted at adults most likely to have contact with very young babies including healthcare and childcare workers, parents and close family contacts. There is also potential for offering vaccination to adults (and their carers and close contacts) whose medical conditions or advanced age may place them at increased risk of more severe pertussis disease. Specific details of immunisation programmes must be made on a country by country basis depending on local circumstances.


Subject(s)
Pertussis Vaccine/pharmacology , Adolescent , Adult , Age Factors , Epidemiologic Factors , Humans , Immunization, Secondary/economics , Infant , Pertussis Vaccine/economics , Risk Factors , Whooping Cough/epidemiology , Whooping Cough/prevention & control , Whooping Cough/transmission
9.
Am J Occup Ther ; 55(3): 260-7, 2001.
Article in English | MEDLINE | ID: mdl-11723966

ABSTRACT

OBJECTIVE: This study examined the validity of the Occupational Identity, Occupational Competency, and Occupational Behavior Settings scales of the second version of the Occupational Performance History Interview (OPHI-II). The study also asked whether the scales' items were targeted to and could effectively discriminate between persons at different levels of adaptation. METHOD: Data were collected from 151 raters on 249 subjects from eight countries and in six languages. Many-faceted Rasch analysis was used to analyze the data. RESULTS: The items of each scale worked effectively to measure the underlying construct for which they were designed. All three scales validly measured more than 90% of the subjects, who varied by nationality, culture, age, and diagnostic status. Each scale's items were appropriately targeted to the subjects, and all three scales distinguished subjects into approximately three different levels. More than 90% of the raters used the three scales validly and had approximately the same degree of severity or leniency. The scales were valid across subjects with physical dysfunction and psychiatric conditions as well as subjects with no active diagnosed condition. CONCLUSION: The three scales of the OPHI-II are valid across age, diagnosis, culture, and language and effectively measure a wide range of persons. Raters can readily use the OPHI-II validly without formal training.


Subject(s)
Occupational Therapy , Adolescent , Adult , Aged , Aged, 80 and over , Female , Humans , Male , Middle Aged , Psychometrics , Surveys and Questionnaires
10.
J Mol Biol ; 312(5): 985-97, 2001 Oct 05.
Article in English | MEDLINE | ID: mdl-11580244

ABSTRACT

Retroviral reverse transcriptases use host cellular tRNAs as primers to initiate reverse transcription. In the case of human immunodeficiency virus type 1 (HIV-1), the 3' 18 nucleotides of human tRNA(Lys,3) are annealed to a complementary sequence on the RNA genome known as the primer binding site (PBS). The HIV-1 nucleocapsid protein (NC) facilitates this annealing. To understand the structural changes that are induced upon NC binding to the tRNA alone, we employed a chemical probing method using the lanthanide metal terbium. At low concentrations of NC, the strong terbium cleavage observed in the core region of the tRNA is significantly attenuated. Thus, NC binding first results in disruption of the tRNA's metal binding pockets, including those that stabilize the D-TPsiC tertiary interaction. When NC concentrations approach the amount needed for complete primer/template annealing, NC further destabilizes the tRNA acceptor-TPsiC stem minihelix, as evidenced by increased terbium cleavage in this domain. A mutant form of NC (SSHS NC), which lacks the zinc finger structures, is able to anneal tRNA(Lys,3) efficiently to the PBS, and to destabilize the tRNA tertiary core, albeit less effectively than wild-type NC. This mutant form of NC does not affect cleavage significantly in the helical regions, even when bound at high concentrations. These results, as well as experiments conducted in the presence of polyLys, suggest that in the absence of the zinc finger structures, NC acts as a polycation, neutralizing the highly negative phosphodiester backbone. The presence of an effective multivalent cationic peptide is sufficient for efficient tRNA primer annealing to the PBS.


Subject(s)
HIV-1 , Nucleic Acid Conformation , Nucleocapsid/chemistry , Nucleocapsid/metabolism , RNA, Transfer, Lys/metabolism , RNA/metabolism , Zinc Fingers/physiology , Amino Acid Sequence , Base Sequence , Binding Sites , Humans , Lysine-tRNA Ligase/metabolism , Models, Molecular , Molecular Chaperones/chemistry , Molecular Chaperones/genetics , Molecular Chaperones/metabolism , Molecular Sequence Data , Mutation/genetics , Nucleic Acid Hybridization , Nucleocapsid/genetics , Polylysine/genetics , Polylysine/metabolism , Protein Binding , RNA/chemistry , RNA/genetics , RNA, Transfer, Lys/chemistry , RNA, Transfer, Lys/genetics , Templates, Genetic , Terbium/metabolism , Zinc Fingers/genetics
11.
Lipids ; 36(7): 713-7, 2001 Jul.
Article in English | MEDLINE | ID: mdl-11521969

ABSTRACT

Animal and human studies designed to examine the effects of alpha-linolenic acid (ALA) and linoleic acid (LA) supplementation on the fatty acid composition of plasma and tissues have demonstrated a marked difference in incorporation into phospholipids of these 18-carbon precursors of the long-chain polyunsaturates. Whereas tissue phospholipid levels are linearly related to dietary ALA and LA, the levels of tissue LA can be 10-fold higher than tissue ALA even when dietary levels are equivalent. There is some dispute whether this disparity is due to ALA being more rapidly metabolized to its products or substantially oxidized by the liver, or whether LA but not ALA is readily incorporated into cellular phospholipids. We examined the level of incorporation of polyunsaturated fatty acids into human respiratory epithelial cell lines (A549, 16HBE) by determining the dose-dependent incorporation of ALA and LA as free fatty acid (5-150 microg FFA/mL). Cell membrane phospholipid ALA and LA were both increased up to approximately 20-30% total fatty acids, with a concomitant decrease predominantly in monounsaturated membrane fatty acids, before significant toxicity was observed (50 microg/mL). Our data support the concept that rather than any inherent inability by human cells to incorporate ALA into membrane phospholipids, the lack of ALA content in human and animal tissues in vivo is due to the rapid metabolism or oxidation of this fatty acid in the liver.


Subject(s)
Bronchi/metabolism , Linoleic Acid/metabolism , Pulmonary Alveoli/metabolism , Respiratory Mucosa/metabolism , alpha-Linolenic Acid/metabolism , Arachidonic Acid/metabolism , Cell Line, Transformed , Cell Survival , Docosahexaenoic Acids/metabolism , Dose-Response Relationship, Drug , Eicosapentaenoic Acid/metabolism , Epithelial Cells/metabolism , Fatty Acids, Nonesterified/metabolism , Fatty Acids, Unsaturated/metabolism , Humans , Linoleic Acid/administration & dosage , Membrane Lipids/metabolism , Respiratory Mucosa/cytology , alpha-Linolenic Acid/administration & dosage
12.
J Biol Chem ; 276(33): 30779-85, 2001 Aug 17.
Article in English | MEDLINE | ID: mdl-11408489

ABSTRACT

Aminoacyl-tRNA synthetases are a family of enzymes responsible for ensuring the accuracy of the genetic code by specifically attaching a particular amino acid to their cognate tRNA substrates. Through primary sequence alignments, prolyl-tRNA synthetases (ProRSs) have been divided into two phylogenetically divergent groups. We have been interested in understanding whether the unusual evolutionary pattern of ProRSs corresponds to functional differences as well. Previously, we showed that some features of tRNA recognition and aminoacylation are indeed group-specific. Here, we examine the species-specific differences in another enzymatic activity, namely amino acid editing. Proofreading or editing provides a mechanism by which incorrectly activated amino acids are hydrolyzed and thus prevented from misincorporation into proteins. "Prokaryotic-like" Escherichia coli ProRS has recently been shown to be capable of misactivating alanine and possesses both pretransfer and post-transfer hydrolytic editing activity against this noncognate amino acid. We now find that two ProRSs belonging to the "eukaryotic-like" group exhibit differences in their hydrolytic editing activity. Whereas ProRS from Methanococcus jannaschii is similar to E. coli in its ability to hydrolyze misactivated alanine via both pretransfer and post-transfer editing pathways, human ProRS lacks these activities. These results have implications for the selection or design of antibiotics that specifically target the editing active site of the prokaryotic-like group of ProRSs.


Subject(s)
Amino Acids/metabolism , Amino Acyl-tRNA Synthetases/metabolism , Escherichia coli/enzymology , Methanococcus/enzymology , RNA Editing , RNA, Transfer, Amino Acyl/metabolism , Alanine/pharmacology , Amino Acid Sequence , Amino Acyl-tRNA Synthetases/chemistry , Humans , Molecular Sequence Data , Proline/pharmacology , Species Specificity
13.
Proc Natl Acad Sci U S A ; 98(11): 6121-6, 2001 May 22.
Article in English | MEDLINE | ID: mdl-11344257

ABSTRACT

The nucleocapsid protein (NC) of HIV type 1 is a nucleic acid chaperone that facilitates the rearrangement of nucleic acids into conformations containing the maximum number of complementary base pairs. We use an optical tweezers instrument to stretch single DNA molecules from the helix to coil state at room temperature in the presence of NC and a mutant form (SSHS NC) that lacks the two zinc finger structures present in NC. Although both NC and SSHS NC facilitate annealing of complementary strands through electrostatic attraction, only NC destabilizes the helical form of DNA and reduces the cooperativity of the helix-coil transition. In particular, we find that the helix-coil transition free energy at room temperature is significantly reduced in the presence of NC. Thus, upon NC binding, it is likely that thermodynamic fluctuations cause continuous melting and reannealing of base pairs so that DNA strands are able to rapidly sample configurations to find the lowest energy state. The reduced cooperativity allows these fluctuations to occur in the middle of complex double-stranded structures. The reduced stability and cooperativity, coupled with the electrostatic attraction generated by the high charge density of NC, is responsible for the nucleic acid chaperone activity of this protein.


Subject(s)
DNA, Viral/metabolism , HIV-1 , Molecular Chaperones/metabolism , Nucleocapsid/metabolism , Zinc Fingers/physiology , Humans
14.
J Paediatr Child Health ; 37(2): 146-51, 2001 Apr.
Article in English | MEDLINE | ID: mdl-11328469

ABSTRACT

OBJECTIVES: To enumerate the cellular composition of the airways in infants with acute bronchiolitis. METHODOLOGY: Cells were obtained by airway lavage from the upper and lower airway and the peripheral blood of infants with respiratory syncytial virus (RSV)+ bronchiolitis, RSV- bronchiolitis and age-matched controls. RESULTS: Neutrophils are the predominant cells present in the upper and lower airway. Neutrophils are present at a higher number/unit volume in the airway than in the peripheral blood. CONCLUSIONS: Neutrophils, being the dominant cellular infiltrate into the airway, are likely to contribute to the pathophysiology of bronchiolitis. Therapies targeted at limiting neutrophil influx or neutrophil-mediated damage in the airway may have a therapeutic role.


Subject(s)
Bronchiolitis, Viral/etiology , Bronchiolitis, Viral/physiopathology , Leukocytes/virology , Respiratory Syncytial Virus Infections/complications , Cell Separation , Flow Cytometry , Humans , Infant , Leukocytes/classification , Respiratory System/virology , South Australia
15.
J Biol Chem ; 276(23): 20286-91, 2001 Jun 08.
Article in English | MEDLINE | ID: mdl-11342535

ABSTRACT

Analysis of prolyl-tRNA synthetase (ProRS) across all three taxonomic domains (Eubacteria, Eucarya, and Archaea) reveals that the sequences are divided into two distinct groups. Recent studies show that Escherichia coli ProRS, a member of the "prokaryotic-like" group, recognizes specific tRNA bases at both the acceptor and anticodon ends, whereas human ProRS, a member of the "eukaryotic-like" group, recognizes nucleotide bases primarily in the anticodon. The archaeal Methanococcus jannaschii ProRS is a member of the eukaryotic-like group, although its tRNA(Pro) possesses prokaryotic features in the acceptor stem. We show here that, in some respects, recognition of tRNA(Pro) by M. jannaschii ProRS parallels that of human, with a strong emphasis on the anticodon and only weak recognition of the acceptor stem. However, our data also indicate differences in the details of the anticodon recognition between these two eukaryotic-like synthetases. Although the human enzyme places a stronger emphasis on G35, the M. jannaschii enzyme places a stronger emphasis on G36, a feature that is shared by E. coli ProRS. These results, interpreted in the context of an extensive sequence alignment, provide evidence of divergent adaptation by M. jannaschii ProRS; recognition of the tRNA acceptor end is eukaryotic-like, whereas the details of the anticodon recognition are prokaryotic-like. This divergence may be a reflection of the unusual dual function of this enzyme, which catalyzes specific aminoacylation with proline as well as with cysteine.


Subject(s)
Amino Acyl-tRNA Synthetases/metabolism , Methanococcus/enzymology , RNA, Transfer, Pro/metabolism , Amino Acid Sequence , Amino Acyl-tRNA Synthetases/chemistry , Binding Sites , Molecular Sequence Data , Nucleic Acid Conformation , RNA, Transfer, Pro/chemistry , Sequence Homology, Amino Acid
16.
J Virol ; 75(11): 5043-8, 2001 Jun.
Article in English | MEDLINE | ID: mdl-11333884

ABSTRACT

During human immunodeficiency virus type 1 (HIV-1) assembly, tRNA(Lys) isoacceptors are selectively incorporated into virions and tRNA(Lys)3 is used as the primer for reverse transcription. We show herein that the tRNA(Lys)-binding protein, lysyl-tRNA synthetase (LysRS), is also selectively packaged into HIV-1. The viral precursor protein Pr55gag alone will package LysRS into Pr55gag particles, independently of tRNA(Lys). With the additional presence of the viral precursor protein Pr160gag-pol, tRNA(Lys) and LysRS are both packaged into the particle. While the predominant cytoplasmic LysRS has an apparent M(r) of 70,000, viral LysRS associated with tRNA(Lys) packaging is shorter, with an apparent M(r) of 63,000. The truncation occurs independently of viral protease and might be required to facilitate interactions involved in the selective packaging and genomic placement of primer tRNA.


Subject(s)
HIV-1/physiology , Lysine-tRNA Ligase/isolation & purification , Animals , Blotting, Western , COS Cells , Gene Products, gag/analysis , Gene Products, gag/metabolism , HIV-1/enzymology , Humans , Lysine-tRNA Ligase/chemistry , Lysine-tRNA Ligase/metabolism , Molecular Weight , Protein Precursors/analysis , Protein Precursors/metabolism , RNA, Transfer, Lys/metabolism , Virus Assembly , gag Gene Products, Human Immunodeficiency Virus , pol Gene Products, Human Immunodeficiency Virus
17.
Biochemistry ; 39(50): 15540-7, 2000 Dec 19.
Article in English | MEDLINE | ID: mdl-11112540

ABSTRACT

Known crystal structures of class II aminoacyl-tRNA synthetases complexed to their cognate tRNAs reveal that critical acceptor stem contacts are made by the variable loop connecting the beta-strands of motif 2 located within the catalytic core of class II synthetases. To identify potential acceptor stem contacts made by Escherichia coli prolyl-tRNA synthetase (ProRS), an enzyme of unknown structure, we performed cysteine-scanning mutagenesis in the motif 2 loop. We identified an arginine residue (R144) that was essential for tRNA aminoacylation but played no role in amino acid activation. Cross-linking experiments confirmed that the end of the tRNA(Pro) acceptor stem is proximal to this motif 2 loop residue. Previous work had shown that the tRNA(Pro) acceptor stem elements A73 and G72 (both strictly conserved among bacteria) are important recognition elements for E. coli ProRS. We carried out atomic group "mutagenesis" studies at these two positions of E. coli tRNA(Pro) and determined that major groove functional groups at A73 and G72 are critical for recognition by ProRS. Human tRNA(Pro), which lacks these elements, is not aminoacylated by the bacterial enzyme. An analysis of chimeric tRNA(Pro) constructs showed that, in addition to A73 and G72, transplantation of the E. coli tRNA(Pro) D-domain was necessary and sufficient to convert the human tRNA into a substrate for the bacterial synthetase. In contrast to the bacterial system, base-specific acceptor stem recognition does not appear to be used by human ProRS. Alanine-scanning mutagenesis revealed that motif 2 loop residues are not critical for tRNA aminoacylation activity of the human enzyme. Taken together, our results illustrate how synthetases and tRNAs have coadapted to changes in protein-acceptor stem recognition through evolution.


Subject(s)
Amino Acyl-tRNA Synthetases/chemistry , Amino Acyl-tRNA Synthetases/genetics , Adaptation, Biological , Amino Acid Sequence , Escherichia coli , Evolution, Molecular , Humans , Molecular Sequence Data , Protein Conformation , Sequence Alignment , Substrate Specificity
18.
RNA ; 6(11): 1672-80, 2000 Nov.
Article in English | MEDLINE | ID: mdl-11105765

ABSTRACT

Lanthanide metals such as terbium have previously been shown to be useful for mapping metal-binding sites in RNA. Terbium binds to the same sites on RNA as magnesium, however, with a much higher affinity. Thus, low concentrations of terbium ions can easily displace magnesium and promote phosphodiester backbone scission. At higher concentrations, terbium cleaves RNA in a sequence-independent manner, with a preference for single-stranded, non-Watson-Crick base-paired regions. Here, we show that terbium is a sensitive probe of human tRNALys,3 tertiary structure and folding. When 1 microM tRNA is used, the optimal terbium ion concentration for detecting Mg2+-induced tertiary structural changes is 50-60 microM. Using these concentrations of RNA and terbium, a magnesium-dependent folding transition with a midpoint (KMg) of 2.6 mM is observed for unmodified human tRNALys,3. At lower Tb3+ concentrations, cleavage is restricted to nucleotides that constitute specific metal-binding pockets. This small chemical probe should also be useful for detecting protein induced structural changes in RNA.


Subject(s)
Nucleic Acid Conformation , RNA, Transfer, Amino Acyl/chemistry , RNA, Transfer/chemistry , Terbium , Autoradiography/methods , Base Sequence , Binding Sites , Electrophoresis, Polyacrylamide Gel/methods , Humans , Magnesium , Models, Molecular , Molecular Sequence Data , Phosphorus Radioisotopes , Ribonuclease T1
19.
Proc Natl Acad Sci U S A ; 97(16): 8916-20, 2000 Aug 01.
Article in English | MEDLINE | ID: mdl-10922054

ABSTRACT

Editing reactions catalyzed by aminoacyl-tRNA synthetases are critical for accurate translation of the genetic code. To date, this activity, whereby misactivated amino acids are hydrolyzed either before or after transfer to noncognate tRNAs, has been characterized extensively only in the case of class I synthetases. Class II synthetases have an active-site architecture that is completely distinct from that of class I. Thus, findings on editing by class I synthetases may not be applicable generally to class II enzymes. Class II Escherichia coli proline-tRNA synthetase is shown here to misactivate alanine and to hydrolyze the noncognate amino acid before transfer to tRNA(Pro). This enzyme also is capable of rapidly deacylating a mischarged Ala-tRNA(Pro) variant. A single cysteine residue (C443) that is located within the class II-specific motif 3 consensus sequence was shown previously to be dispensable for proline-tRNA synthetase aminoacylation activity. We show here that C443 is critical for the hydrolytic editing of Ala-tRNA(Pro) by this class II synthetase.


Subject(s)
Amino Acyl-tRNA Synthetases/metabolism , RNA Editing , Amino Acyl-tRNA Synthetases/chemistry , Cysteine/metabolism , Escherichia coli/enzymology , Hydrolysis
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