Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 21
Filter
1.
J Nurs Meas ; 31(3): 404-411, 2023 09 01.
Article in English | MEDLINE | ID: mdl-35793860

ABSTRACT

Background and Purpose: Caring is an essential value in nursing, it's crucial in pediatric hemato-oncology: we tested the Nurse Caring Behavior Scale (NCBS) in this setting. Methods: The NCBS is a 14-item validated psychometric questionnaire: caregivers and nurses adapted versions were used. Descriptive statistics and exploratory factor analysis (EFA) were used. Results: The questionnaires were completed by 188 caregivers and 193 nurses. The two data sets were suitable for EFA and fitted with one-solution factor analysis; factor loading showed values >0.40 (>0.60 for caregivers). The mean scores were: 4.5 (range: 1-5) for caregivers and 4.7 (range: 1-5) for nurses. Conclusion: The two validated versions can be used on a wider nurses and caregivers sample and provide an instrument for the development of nursing protocols based on caring.


Subject(s)
Caregivers , Humans , Child , Cross-Sectional Studies , Reproducibility of Results , Surveys and Questionnaires , Psychometrics
2.
Front Plant Sci ; 14: 1306491, 2023.
Article in English | MEDLINE | ID: mdl-38239208

ABSTRACT

The model legume Medicago truncatula establishes a symbiosis with soil bacteria (rhizobia) that carry out symbiotic nitrogen fixation (SNF) in plant root nodules. SNF requires the exchange of nutrients between the plant and rhizobia in the nodule that occurs across a plant-derived symbiosome membrane. One iron transporter, belonging to the Vacuolar iron Transporter-Like (VTL) family, MtVTL8, has been identified as essential for bacteria survival and therefore SNF. In this work we investigated the spatial expression of MtVTL8 in nodules and addressed whether it could be functionally interchangeable with a similar nodule-expressed iron transporter, MtVTL4. Using a structural model for MtVTL8 and the previously hypothesized mechanism for iron transport in a phylogenetically-related Vacuolar Iron Transporter (VIT), EgVIT1 with known crystal structure, we identified critical amino acids and obtained their mutants. Mutants were tested in planta for complementation of an SNF defective line and in an iron sensitive mutant yeast strain. An extended phylogenetic assessment of VTLs and VITs showed that amino acids critical for function are conserved differently in VTLs vs. VITs. Our studies showed that some amino acids are essential for iron transport leading us to suggest a model for MtVTL8 function, one that is different for other iron transporters (VITs) studied so far. This study extends the understanding of iron transport mechanisms in VTLs as well as those used in SNF.

3.
Front Endocrinol (Lausanne) ; 13: 918682, 2022.
Article in English | MEDLINE | ID: mdl-36004351

ABSTRACT

The WNT1 gene is crucial for bone development and homeostasis. Homozygous mutations in WNT1 cause severe bone fragility known as osteogenesis imperfecta type XV. Moreover, heterozygous WNT1 mutations have been found in adults with early-onset osteoporosis. We identified a 35 year-old Caucasian woman who experienced multiple vertebral fractures two months after her second pregnancy. There was no history of risk factors for secondary osteoporosis or family history of osteoporosis. Dual-energy X-ray absorptiometry confirmed a marked reduction of bone mineral density (BMD) at the lumbar spine (0.734 g/cm2, Z-score -2.8), femoral neck (0.48 g/cm2, Z-score -3.5), and total hip (0.589 g/cm2, Z-score -3.0). Blood tests excluded secondary causes of bone fragility. Genetic analysis revealed a heterozygous missense mutation (p.Leu370Val) in the WNT1 gene. Varsome classified it as a variant of uncertain significance. However, the fact that the Leucine residue at position 370 is highly conserved among vertebrate species and the variant has a very low allelic frequency in the general population would exclude the possibility of a polymorphism. The patient was treated for two years with teriparatide therapy associated with calcium and vitamin D supplements. During the follow-up period she did not report further clinical fractures. After 24 months of teriparatide, BMD increased at lumbar spine (+14.6%), femoral neck (+8.3%) and total hip (+4.9%) compared to baseline. We confirm that the heterozygous WNT1 mutation could cause a variable bone fragility and low turnover osteoporosis. We suggest that teriparatide is one of the most appropriate available therapies for this case.


Subject(s)
Osteogenesis Imperfecta , Osteoporosis , Adult , Bone Density/genetics , Female , Humans , Lumbar Vertebrae , Osteogenesis Imperfecta/genetics , Osteoporosis/drug therapy , Osteoporosis/genetics , Pregnancy , Teriparatide/therapeutic use
4.
Ann Clin Transl Neurol ; 9(3): 404-409, 2022 03.
Article in English | MEDLINE | ID: mdl-35166467

ABSTRACT

The study reports real world data in type 2 and 3 SMA patients treated for at least 2 years with nusinersen. Increase in motor function was observed after 12 months and during the second year. The magnitude of change was variable across age and functional subgroup, with the largest changes observed in young patients with higher function at baseline. When compared to natural history data, the difference between study cohort and untreated patients swas significant on both Hammersmith Functional Motor Scale and Revised Upper Limb Module both at 12 months and at 24 months.


Subject(s)
Muscular Atrophy, Spinal , Cohort Studies , Humans , Muscular Atrophy, Spinal/drug therapy , Oligonucleotides/pharmacology , Oligonucleotides/therapeutic use , Upper Extremity
5.
Eur J Pediatr ; 181(5): 1923-1932, 2022 May.
Article in English | MEDLINE | ID: mdl-35048179

ABSTRACT

The aim of this retrospective study was to review body mass index (BMI) in a large cohort of Italian pediatric type 2 spinal muscular atrophy (SMA) patients, aged between 0 and 20 years and to establish possible differences in relation to a number of variables such as ventilation, motor function, and survival motor neuron 2 gene copies. Cross-sectional data were collected from 102 patients for a total of 344 visits. Standard growth charts for height and weight were used as reference, with age adjusted BMI calculated using the Center for Disease and Prevention Children's BMI Tool. In the 344 visits, weight ranged between 3.90 and 83 kg, and the BMI between 8.4 and 31.6 with a BMI/age z-scores < - 2SD present in 28% and BMI/age z-scores > + 2SD in 9% of the measurements. The BMI/age z-scores were relatively stable < 5 years of age with an increasing number of patients < - 2SD after the age of 5, and a wider range of BMI/age z-scores after the age of 13. A difference on the BMI/age z-scores was found among the different age subgroups (< 5, 5-12, ≥ 13 years). A multivariate analysis in 58 patients with longitudinal assessments showed that baseline BMI/age z-scores and gender were significantly contributing to the changes while other variables were not. CONCLUSION: Our results confirm that careful surveillance of weight and BMI/age z-scores is needed in type 2 SMA. Further studies, including assessments of chewing and swallowing and of lean/fat body mass, will help to better understand the possible mechanisms underlying weight issues. WHAT IS KNOWN: • Feeding difficulties have been reported in a few studies and were invariably found in patients with type 1 SMA. • Type 2 SMA patients often have low BMI with a relevant number of patients requiring tube feeding. WHAT IS NEW: • Reduction in BMI/age z-score overtime appeared to depend on baseline BMI/age z-score and gender. • Patients with a low BMI/age z-score were at higher risk of developing further reduction.


Subject(s)
Muscular Atrophy, Spinal , Adolescent , Adult , Body Mass Index , Body Weight , Child , Child, Preschool , Cross-Sectional Studies , Humans , Infant , Infant, Newborn , Longitudinal Studies , Muscular Atrophy, Spinal/epidemiology , Retrospective Studies , Young Adult
7.
IEEE Trans Pattern Anal Mach Intell ; 44(2): 955-968, 2022 Feb.
Article in English | MEDLINE | ID: mdl-32759080

ABSTRACT

Albeit great success has been achieved in image defocus blur detection, there are still several unsolved challenges, e.g., interference of background clutter, scale sensitivity and missing boundary details of blur regions. To deal with these issues, we propose a deep neural network which recurrently fuses and refines multi-scale deep features (DeFusionNet) for defocus blur detection. We first fuse the features from different layers of FCN as shallow features and semantic features, respectively. Then, the fused shallow features are propagated to deep layers for refining the details of detected defocus blur regions, and the fused semantic features are propagated to shallow layers to assist in better locating blur regions. The fusion and refinement are carried out recurrently. In order to narrow the gap between low-level and high-level features, we embed a feature adaptation module before feature propagating to exploit the complementary information as well as reduce the contradictory response of different feature layers. Since different feature channels are with different extents of discrimination for detecting blur regions, we design a channel attention module to select discriminative features for feature refinement. Finally, the output of each layer at last recurrent step are fused to obtain the final result. We collect a new dataset consists of various challenging images and their pixel-wise annotations for promoting further study. Extensive experiments on two commonly used datasets and our newly collected one are conducted to demonstrate both the efficacy and efficiency of DeFusionNet.

8.
Orphanet J Rare Dis ; 16(1): 425, 2021 10 12.
Article in English | MEDLINE | ID: mdl-34641930

ABSTRACT

BACKGROUND: X-linked myotubular myopathy (XLMTM) is a rare congenital myopathy resulting from pathogenic variants in the MTM1 gene. Affected male subjects typically present with severe hypotonia and respiratory distress at birth and they often require intensive supportive care. Long-term survivors are often non-ambulant, ventilator and feeding tube-dependent and they generally show additional organ manifestations, indicating that myotubularin does play a vital role in tissues other than muscle. For XLMTM several therapeutic strategies are under investigation. For XLMTM several therapeutic strategies are under investigation including a study of intravenous MTM1 gene transfer using a recombinant AAV8 vector of which has some concerns arises due to hepatotoxicity. RESULTS: We report prospective and retrospective clinical data of 12 XLMTM patients collected over a period of up to 10 years. In particular, we carried out a thorough review of the data about incidence and the course of hepatobiliary disease in our case series. CONCLUSIONS: We demonstrate that hepatobiliary disease represents a common comorbidity of XLMTM that seems irrespective to age and diseases severity. We recommend to carefully explore and monitor the hepatobiliary function in XLMTM patients. We believe that a better understanding of the pathogenic mechanisms that induce hepatobiliary damage is essential to understand the fatal events that may occur in the gene therapy program.


Subject(s)
Digestive System Diseases , Myopathies, Structural, Congenital , Comorbidity , Humans , Infant, Newborn , Male , Muscle, Skeletal , Prospective Studies , Retrospective Studies
9.
Front Plant Sci ; 12: 685334, 2021.
Article in English | MEDLINE | ID: mdl-34276736

ABSTRACT

Symbiotic nitrogen fixation is a complex and regulated process that takes place in root nodules of legumes and allows legumes to grow in soils that lack nitrogen. Nitrogen is mostly acquired from the soil as nitrate and its level in the soil affects nodulation and nitrogen fixation. The mechanism(s) by which legumes modulate nitrate uptake to regulate nodule symbiosis remain unclear. In Medicago truncatula, the MtNPF1.7 transporter has been shown to control nodulation, symbiosis, and root architecture. MtNPF1.7 belongs to the nitrate/peptide transporter family and is a symporter with nitrate transport driven by proton(s). In this study we combined in silico structural predictions with in planta complementation of the severely defective mtnip-1 mutant plants to understand the role of a series of distinct amino acids in the transporter's function. Our results support hypotheses about the functional importance of the ExxE(R/K) motif including an essential role for the first glutamic acid of the motif in proton(s) and possibly substrate transport. Results reveal that Motif A, a motif conserved among major facilitator transport (MFS) proteins, is essential for function. We hypothesize that it participates in intradomain packing of transmembrane helices and stabilizing one conformation during transport. Our results also question the existence of a putative TMH4-TMH10 salt bridge. These results are discussed in the context of potential nutrient transport functions for MtNPF1.7. Our findings add to the knowledge of the mechanism of alternative conformational changes as well as symport transport in NPFs and enhance our knowledge of the mechanisms for nitrate signaling.

10.
Open Biol ; 11(4): 200395, 2021 04.
Article in English | MEDLINE | ID: mdl-33823659

ABSTRACT

Diatoms are one of the major and most diverse groups of phytoplankton, with chimeric genomes harbouring a combination of genes of bacterial, animal and plant origin. They have developed sophisticated mechanisms to face environmental variations. In marine environments, nutrients concentration shows significant temporal and spatial variability, influencing phytoplankton growth. Among nutrients, nitrogen, present at micromolar levels, is often a limiting resource. Here, we report a comprehensive characterization of the Nitrate Transporter 1/Peptide Transporter Family (NPF) in diatoms, diNPFs. NPFs are well characterized in many organisms where they recognize a broad range of substrates, ranging from short-chained di- and tri-peptides in bacteria, fungi and mammals to a wide variety of molecules including nitrate in higher plants. Scarce information is available for diNPFs. We integrated-omics, phylogenetic, structural and expression analyses, to infer information on their role in diatoms. diNPF genes diverged to produce two distinct clades with strong sequence and structural homology with either bacterial or plant NPFs, with different predicted sub-cellular localization, suggesting that the divergence resulted in functional diversification. Moreover, transcription analysis of diNPF genes under different laboratory and environmental growth conditions suggests that diNPF diversification led to genetic adaptations that might contribute to diatoms ability to flourish in diverse environmental conditions.


Subject(s)
Biological Evolution , Diatoms/physiology , Genomics , Nitrate Transporters/chemistry , Nitrate Transporters/physiology , Protein Conformation , Binding Sites , Computational Biology/methods , Databases, Genetic , Diatoms/classification , Gene Expression Profiling , Genome , Genomics/methods , Models, Molecular , Phylogeny , Phylogeography , Protein Binding , Structure-Activity Relationship , Transcription Factors/metabolism
13.
Prof Inferm ; 73(4): 270-277, 2020.
Article in Italian | MEDLINE | ID: mdl-33780611

ABSTRACT

INTRODUCTION: The COVID-19 pandemic is causing a global health emergency. Health systems are under extreme pressure because of the outbreak. Pediatric population seems to be less prone to develop a severe course of the disease. Still the information about COVID-19 infection and children affected by cancer are few. AIM: This survey aims to highlight preventive and control measures to manage COVID-19 infection in Italian Pediatric Oncology and Hematology Association (AIEOP) centers. METHODS: A multicenter, descriptive survey design was used. All the AIEOP centers were invited to complete an on-line survey. Data collection was performed between March 15, 2020 and April 15, 2020. RESULTS: Thirty six out of 48 centers responded to the survey. All the centers implemented similar preventive measures in order to control the COVID-19 spread and 77.8% of centers have created structured pathways, specific protocols or procedures; 30% of centers reduced the number of inpatient beds and 90% outpatient activity. The prevalence data collected report 14 children positive and 35 healthcare professionals positive. DISCUSSION: COVID-19 is not spreading homogeneously in Italy and children are less infected. It will be necessary to define new processes and new strategies to ensure safety and continuity of care to children affected by cancer, even in the future, when the lockdown will end, and new measures will be implemented.


Subject(s)
COVID-19/prevention & control , Cancer Care Facilities , Continuity of Patient Care , Hematologic Neoplasms/therapy , Neoplasms/therapy , Child , Health Care Surveys , Humans , Italy
14.
Sci Rep ; 9(1): 3321, 2019 Mar 01.
Article in English | MEDLINE | ID: mdl-30824809

ABSTRACT

Magmas discharged during individual volcanic eruptions commonly display compositional variations interpreted as new arrivals at shallow depth of more primitive, hotter, volatile-rich magma batches mixing with resident, colder, partially degassed magma. Heterogeneities in eruption products are often interpreted as evidence of short times of order tens of hours from new magma arrival to eruption, raising concerns for emergency planning. We show here, through numerical simulations, that magma convection and mixing in a shallow magma chamber can result in long-lived, dynamically stable configurations with coexistence of magmas from nearly pure to variably mixed end-member compositions. Short mixing time scales may therefore relate to sin-eruptive processes, as heterogeneities found in the eruptive products are not necessarily the fingerprint of new magma arrival shortly preceding or triggering the eruption.

15.
Front Plant Sci ; 9: 1668, 2018.
Article in English | MEDLINE | ID: mdl-30564251

ABSTRACT

Nitrogen is essential for all living species and may be taken up from the environment in different forms like nitrate or peptides. In plants, members of a transporter family named NPFs transport nitrate and peptides across biological membranes. NPFs are phylogenetically related to a family of peptide transporters (PTRs) or proton-coupled oligopeptide transporters (POTs) that are evolutionarily conserved in all organisms except in Archaea. POTs are present in low numbers in bacteria, algae and animals. NPFs have expanded in plants and evolved to transport a wide range of substrates including phytohormones and glucosinolates. Functional studies have shown that most NPFs, like POTs, operate as symporters with simultaneous inwardly directed movement of protons. Here we focus on four structural features of NPFs/POTs/PTRs that have been shown by structural and functional studies to be essential to proton-coupled symport transport. The first two features are implicated in proton binding and transport: a conserved motif named ExxER/K, located in the first transmembrane helix (TMH1) and a D/E residue in TMH7 that has been observed in some bacterial and algal transporters. The third and fourth features are two inter-helical salt bridges between residues on TMH1 and TMH7 or TMH4 and TMH10. To understand if the mechanism of transport is conserved in NPFs with the expansion to novel substrates, we collected NPFs sequences from 42 plant genomes. Sequence alignment revealed that the ExxER/K motif is not strictly conserved and its conservation level is different in the NPF subfamilies. The proton binding site on TMH7 is missing in all NPFs with the exception of two NPFs from moss. The two moss NPFs also have a positively charged amino acid on TMH1 that can form the salt bridge with the TMH7 negative residue. None of the other NPFs we examined harbor residues that can form the TMH1-TMH7 salt bridge. In contrast, the amino acids required to form the TMH4-TMH10 salt bridge are highly conserved in NPFs, with some exceptions. These results support the need for further biochemical and structural studies of individual NPFs for a better understanding of the transport mechanism in this family of transporters.

16.
Amino Acids ; 48(2): 427-36, 2016 Feb.
Article in English | MEDLINE | ID: mdl-26403849

ABSTRACT

Asymmetric dimethyl L-arginine (ADMA) is generated within cells and in mitochondria when proteins with dimethylated arginine residues are degraded. The aim of this study was to identify the carrier protein(s) that transport ADMA across the inner mitochondrial membrane. It was found that the recombinant, purified mitochondrial solute carrier SLC25A2 when reconstituted into liposomes efficiently transports ADMA in addition to its known substrates arginine, lysine, and ornithine and in contrast to the other known mitochondrial amino acid transporters SLC25A12, SLC25A13, SLC25A15, SLC25A18, SLC25A22, and SLC25A29. The widely expressed SLC25A2 transported ADMA across the liposomal membrane in both directions by both unidirectional transport and exchange against arginine or lysine. The SLC25A2-mediated ADMA transport followed first-order kinetics, was nearly as fast as the transport of the best SLC25A2 substrates known so far, and was highly specific as symmetric dimethylarginine (SDMA) was not transported at all. Furthermore, ADMA inhibited SLC25A2 activity with an inhibition constant of 0.38 ± 0.04 mM, whereas SDMA inhibited it poorly. We propose that a major function of SLC25A2 is to export ADMA from mitochondria missing the mitochondrial ADMA-metabolizing enzyme AGXT2. There is evidence that ADMA can also be imported into mitochondria, e.g., in kidney proximal tubulus cells, to be metabolized by AGXT2. SLC25A2 may also mediate this transport function.


Subject(s)
Amino Acid Transport Systems, Basic/metabolism , Arginine/analogs & derivatives , Carrier Proteins/metabolism , Mitochondria/metabolism , Mitochondrial Membranes/metabolism , Arginine/metabolism , Biological Transport , Cell Line, Tumor , Humans , Kidney Tubules, Proximal/metabolism , Transaminases
17.
J Biol Chem ; 289(19): 13374-84, 2014 May 09.
Article in English | MEDLINE | ID: mdl-24652292

ABSTRACT

The human genome encodes 53 members of the solute carrier family 25 (SLC25), also called the mitochondrial carrier family, many of which have been shown to transport carboxylates, amino acids, nucleotides, and cofactors across the inner mitochondrial membrane, thereby connecting cytosolic and matrix functions. In this work, a member of this family, SLC25A29, previously reported to be a mitochondrial carnitine/acylcarnitine- or ornithine-like carrier, has been thoroughly characterized biochemically. The SLC25A29 gene was overexpressed in Escherichia coli, and the gene product was purified and reconstituted in phospholipid vesicles. Its transport properties and kinetic parameters demonstrate that SLC25A29 transports arginine, lysine, homoarginine, methylarginine and, to a much lesser extent, ornithine and histidine. Carnitine and acylcarnitines were not transported by SLC25A29. This carrier catalyzed substantial uniport besides a counter-exchange transport, exhibited a high transport affinity for arginine and lysine, and was saturable and inhibited by mercurial compounds and other inhibitors of mitochondrial carriers to various degrees. The main physiological role of SLC25A29 is to import basic amino acids into mitochondria for mitochondrial protein synthesis and amino acid degradation.


Subject(s)
Carnitine Acyltransferases/chemistry , Mitochondria/genetics , Mitochondrial Proteins/chemistry , Amino Acids, Basic/chemistry , Amino Acids, Basic/genetics , Amino Acids, Basic/metabolism , Biological Transport, Active/physiology , Carnitine Acyltransferases/genetics , Carnitine Acyltransferases/metabolism , Escherichia coli/chemistry , Escherichia coli/genetics , Escherichia coli/metabolism , Humans , Kinetics , Mitochondria/metabolism , Mitochondrial Proteins/genetics , Mitochondrial Proteins/metabolism , Recombinant Proteins/chemistry , Recombinant Proteins/genetics , Recombinant Proteins/metabolism
18.
J Matern Fetal Neonatal Med ; 27(11): 1151-7, 2014 Jul.
Article in English | MEDLINE | ID: mdl-24093425

ABSTRACT

The determination of fetal head position can be useful in labor to predict the success of labor management, especially in case of malpositions. Malpositions are abnormal positions of the vertex of the fetal head and account for the large part of indication for cesarean sections for dystocic labor. The occiput posterior position occurs in 15-25% of patients before labor at term and, however, most occiput posterior presentations rotate during labor, so that the incidence of occiput posterior at vaginal birth is approximately 5-7%. Persistence of the occiput posterior position is associated with higher rate of interventions and with maternal and neonatal complications and the knowledge of the exact position of the fetal head is of paramount importance prior to any operative vaginal delivery, for both the safe positioning of the instrument that may be used (i.e. forceps versus vacuum) and for its successful outcome. Ultrasound (US) diagnosed occiput posterior position during labor can predict occiput posterior position at birth. By these evidences, the time requested for fetal head descent and the position in the birth canal, had an impact on the diagnosis of labor progression or arrested labor. To try to reduce this pitfalls, authors developed a new algorithm, applied to intrapartum US and based on suitable US pictures, that sets out, in detail, the quantitative evaluation, in degrees, of the occiput posterior position of the fetal head in the pelvis and the birth canal, respectively, in the first and second stage of labor. Authors tested this computer system in a settle of patients in labor.


Subject(s)
Algorithms , Computer Simulation , Delivery, Obstetric/methods , Labor Presentation , Obstetric Labor Complications/diagnostic imaging , Adult , Delivery, Obstetric/statistics & numerical data , Female , Fetus , Head/diagnostic imaging , Humans , Infant, Newborn , Obstetric Labor Complications/epidemiology , Pregnancy , Trial of Labor , Ultrasonography, Prenatal
19.
Biochemistry ; 47(1): 218-29, 2008 Jan 08.
Article in English | MEDLINE | ID: mdl-18069799

ABSTRACT

The ubiquitous class I basic helix-loop-helix (bHLH) factor E47 forms heterodimers with multiple tissue specific class II bHLH proteins to regulate distinct differentiation pathways. In order to define how class I- class II heterodimer partners are selected, we determined the crystal structure of the E47-NeuroD1-bHLH dimer in complex with the insulin promoter E-box sequence. Purification of the bHLH domain of E47-NeuroD1 indicates that E47 heterodimers are stable in solution. The interactions between E47 and NeuroD1 in the heterodimer are comparable to the interactions between E47 monomers in the homodimer, including hydrogen bonding, buried hydrophobic surface, and packing interactions. This is consistent with a model in which E47-NeuroD1 heterodimers are favored due to the instability of NeuroD1 homodimers. Although E47-NeuroD1 is oriented uniquely on the E-box sequence (CATCTG) within the promoter of the insulin gene, no direct contacts are observed with the central base pairs within this E-box sequence. We propose that concerted domain motions allow E47 to form specific base contacts in solution. NeuroD1 is restrained from adopting the same base contacts by an additional phosphate backbone interaction by the neurogenic-specific residue His115. Orienting E47-NeuroD1 on promoters may foster protein-protein contacts essential to initiate transcription.


Subject(s)
Basic Helix-Loop-Helix Transcription Factors/metabolism , DNA/metabolism , Nerve Tissue Proteins/metabolism , TCF Transcription Factors/metabolism , Amino Acid Sequence , Animals , Base Sequence , Basic Helix-Loop-Helix Transcription Factors/chemistry , Binding Sites , Crystallography, X-Ray , DNA/chemistry , DNA/genetics , Dimerization , Humans , Mice , Models, Molecular , Molecular Sequence Data , Nerve Tissue Proteins/chemistry , Protein Binding , Protein Structure, Secondary , Protein Structure, Tertiary , Sequence Homology, Amino Acid , TCF Transcription Factors/chemistry , Transcription Factor 7-Like 1 Protein
20.
Biochemistry ; 46(11): 2948-57, 2007 Mar 20.
Article in English | MEDLINE | ID: mdl-17315980

ABSTRACT

Pancreatic and duodenal homeobox 1 (Pdx1) is a homeodomain transcription factor belonging to the ParaHox family. Pdx1 plays an essential role in pancreatic endocrine and exocrine cell development and maintenance of adult islet beta-cell function. Mutations in the human pdx1 gene are linked to an early onset form of non-insulin-dependent diabetes mellitus, MODY-4. We demonstrate that the homeodomain reproduces the binding specificity of the full-length protein. We report the 2.4 A resolution crystal structure of the homeodomain bound to a target DNA. The two Pdx1/DNA complexes in the asymmetric unit display conformational differences: in the DNA curvature, the orientation of the homeodomain in the major groove, and the order of the N-terminal arm. Comparing the two complexes indicates invariant protein-DNA contacts, and variant contacts that are unique to each binding orientation. An induced fit model is proposed that depends on the DNA conformation and provides a mechanism for nonlocal contributions to binding specificity.


Subject(s)
DNA/metabolism , Homeodomain Proteins/genetics , Homeodomain Proteins/metabolism , Trans-Activators/genetics , Trans-Activators/metabolism , Amino Acid Sequence , Animals , Base Sequence , Cricetinae , Crystallization , Crystallography, X-Ray , Mesocricetus , Models, Molecular , Molecular Sequence Data , Nucleic Acid Conformation , Protein Conformation , Sequence Alignment
SELECTION OF CITATIONS
SEARCH DETAIL
...