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1.
An. sist. sanit. Navar ; (Monografía n 8): 411-423, Jun 23, 2023. graf, tab
Article in Spanish | IBECS | ID: ibc-222485

ABSTRACT

La hospitalización a domicilio (HAD) es una alternativa asistencial del Área de Salud de Pamplona consistente en un modelo organizativo capaz de dispensar a pacientes en su propiodomicilio un conjunto de actividades y cuidados sanitarios con complejidad, intensidad y duración comparables a los de una hospitalización convencional cuando todavía precisan de unavigilancia activa y una asistencia compleja. Ante el incremento progresivo de ingresos en el Hospital Universitario de Navarra (HUN) y lasprevisiones existentes para las siguientes semanas, el lunes 9 de marzo de 2020 se decide creardentro de la unidad de HAD del HUN una unidad específica centrada en COVID-19 y que, portanto, entra en el dispositivo de atención a los pacientes con infección por COVID-19. Debido al incremento progresivo en el número de ingresos hospitalarios, el día 26 de marzo elServicio Navarro de Salud-Osasunbidea (SNS-O) decide medicalizar el hotel Iruña Park con elobjetivo de incrementar el número de camas hospitalarias disponibles. En este documento se expone la actividad realizada en las tres primeras olas por la unidad deHAD del HUN en la atención domiciliaria y en la primera ola en el hotel medicalizado.(AU)


Subject(s)
Humans , Home Care Services, Hospital-Based , Hospitals, University , Pandemics , Coronavirus Infections/epidemiology , Spain , Public Health , Health Services
2.
Front Cell Dev Biol ; 10: 884689, 2022.
Article in English | MEDLINE | ID: mdl-35646900

ABSTRACT

Plasmalogens are glycerophospholipids with a hallmark sn-1 vinyl ether bond that endows them with unique physical-chemical properties. They have proposed biological roles in membrane organization, fluidity, signaling, and antioxidative functions, and abnormal plasmalogen levels correlate with various human pathologies, including cancer and Alzheimer's disease. The presence of plasmalogens in animals and in anaerobic bacteria, but not in plants and fungi, is well-documented. However, their occurrence in the obligately aerobic myxobacteria, exceptional among aerobic bacteria, is often overlooked. Tellingly, discovery of the key desaturase indispensable for vinyl ether bond formation, and therefore fundamental in plasmalogen biogenesis, emerged from delving into how the soil myxobacterium Myxococcus xanthus responds to light. A recent pioneering study unmasked myxobacterial CarF and its human ortholog TMEM189 as the long-sought plasmanylethanolamine desaturase (PEDS1), thus opening a crucial door to study plasmalogen biogenesis, functions, and roles in disease. The findings demonstrated the broad evolutionary sweep of the enzyme and also firmly established a specific signaling role for plasmalogens in a photooxidative stress response. Here, we will recount our take on this fascinating story and its implications, and review the current state of knowledge on plasmalogens, their biosynthesis and functions in the aerobic myxobacteria.

3.
Environ Microbiol ; 24(4): 1865-1886, 2022 04.
Article in English | MEDLINE | ID: mdl-35005822

ABSTRACT

Light-induced carotenogenesis in Myxococcus xanthus is controlled by the B12 -based CarH repressor and photoreceptor, and by a separate intricate pathway involving singlet oxygen, the B12 -independent CarH paralogue CarA and various other proteins, some eukaryotic-like. Whether other myxobacteria conserve these pathways and undergo photoregulated carotenogenesis is unknown. Here, comparative analyses across 27 Myxococcales genomes identified carotenogenic genes, albeit arranged differently, with carH often in their genomic vicinity, in all three Myxococcales suborders. However, CarA and its associated factors were found exclusively in suborder Cystobacterineae, with carA-carH invariably in tandem in a syntenic carotenogenic operon, except for Cystobacter/Melittangium, which lack CarA but retain all other factors. We experimentally show B12 -mediated photoregulated carotenogenesis in representative myxobacteria, and a remarkably plastic CarH operator design and DNA binding across Myxococcales. Unlike the two characterized CarH from other phyla, which are tetrameric, Cystobacter CarH (the first myxobacterial homologue amenable to analysis in vitro) is a dimer that combines direct CarH-like B12 -based photoregulation with CarA-like DNA binding and inhibition by an antirepressor. This study provides new molecular insights into B12 -dependent photoreceptors. It further establishes the B12 -dependent pathway for photoregulated carotenogenesis as broadly prevalent across myxobacteria and its evolution, exclusively in one suborder, into a parallel complex B12 -independent circuit.


Subject(s)
Gene Expression Regulation, Bacterial , Myxococcales , Bacterial Proteins/metabolism , DNA/metabolism , Myxococcales/genetics , Myxococcales/metabolism , Phosphothreonine/analogs & derivatives , Repressor Proteins/metabolism
4.
Animals (Basel) ; 11(7)2021 Jun 29.
Article in English | MEDLINE | ID: mdl-34209530

ABSTRACT

Vitamin B and trace minerals are crucial molecular signals involved in many biological pathways; however, their bioavailability is compromised in high-producing ruminant animals. So far, studies have mainly focused on the effects of these micronutrients on animal performance, but their use in a rumen-protected form and their impact on liver metabolism in finishing beef cattle is poorly known. We used a shotgun proteomic approach combined with biological network analyses to assess the effects of a rumen-protected B-vitamin blend, as well as those of hydroxy trace minerals, on the hepatic proteome. A total of 20 non-castrated Nellore males with 353 ± 43 kg of initial body weight were randomly assigned to one of the following treatments: CTRL-inorganic trace minerals without supplementation of a protected vitamin B blend, or SUP-supplementation of hydroxy trace minerals and a protected vitamin B blend. All animals were fed the same amount of the experimental diet for 106 days, and liver biopsies were performed at the end of the experimental period. Supplemented animals showed 37 up-regulated proteins (p < 0.10), and the enrichment analysis revealed that these proteins were involved in protein folding (p = 0.04), mitochondrial respiratory chain complex I (p = 0.01) and IV (p = 0.01), chaperonin-containing T-complex 2 (p = 0.01), glutathione metabolism (p < 0.01), and other aspects linked to oxidative-stress responses. These results indicate that rumen-protected vitamin B and hydroxy trace mineral supplementation during the finishing phase alters the abundance of proteins associated with the electron transport chain and other oxidation-reduction pathways, boosting the production of reactive oxygen species, which appear to modulate proteins linked to oxidative-damage responses to maintain cellular homeostasis.

5.
Microorganisms ; 9(5)2021 May 15.
Article in English | MEDLINE | ID: mdl-34063365

ABSTRACT

Myxobacteria are Gram-negative δ-proteobacteria found predominantly in terrestrial habitats and often brightly colored due to the biosynthesis of carotenoids. Carotenoids are lipophilic isoprenoid pigments that protect cells from damage and death by quenching highly reactive and toxic oxidative species, like singlet oxygen, generated upon growth under light. The model myxobacterium Myxococcus xanthus turns from yellow in the dark to red upon exposure to light because of the photoinduction of carotenoid biosynthesis. How light is sensed and transduced to bring about regulated carotenogenesis in order to combat photooxidative stress has been extensively investigated in M. xanthus using genetic, biochemical and high-resolution structural methods. These studies have unearthed new paradigms in bacterial light sensing, signal transduction and gene regulation, and have led to the discovery of prototypical members of widely distributed protein families with novel functions. Major advances have been made over the last decade in elucidating the molecular mechanisms underlying the light-dependent signaling and regulation of the transcriptional response leading to carotenogenesis in M. xanthus. This review aims to provide an up-to-date overview of these findings and their significance.

6.
Meat Sci ; 177: 108495, 2021 Jul.
Article in English | MEDLINE | ID: mdl-33756247

ABSTRACT

We aimed to investigate differences in the synthesis and metabolism of intramuscular collagen in the Longissimus thoracis (LT) muscle between heifers and cull-cows fed high-energy diet. Ten cull-cows, (74.9 ± 3.2 months age, weighing 536 ± 14.55 kg) and ten heifers (18.4 ± 3.2 months age, weighting 310.5 ± 14.5 kg) were fed with high-energy diets for 150 days. The total collagen content did not differ between treatments. Greater collagen solubility was observed in heifers than cull-cows, although no differences in lysyl oxidase activity were observed between treatments. No differences were observed for mRNA expression of CO1A1, MMP2, MMP9 and TIMP2 between treatments. However, cull-cows presented greater mRNA expression of COL3A1, TIMP1 and TIMP3 than heifers. Our data give no indication that feeding a high-energy diet to cull-cows decreases the concentration of intramuscular collagen in the LT muscle or increases its solubility in respect to the collagen solubility in LT muscles from heifers on the same diet.


Subject(s)
Collagen/metabolism , Diet/veterinary , Muscle, Skeletal/chemistry , Red Meat/analysis , Animal Feed/analysis , Animals , Cattle , Collagen/chemistry , Collagen/genetics , Female , Gene Expression , Muscle, Skeletal/metabolism , Protein-Lysine 6-Oxidase/analysis , RNA, Messenger/metabolism , Shear Strength , Solubility
7.
Science ; 366(6461): 128-132, 2019 10 04.
Article in English | MEDLINE | ID: mdl-31604315

ABSTRACT

Plasmalogens are glycerophospholipids with a hallmark sn-1 vinyl ether bond. These lipids are found in animals and some bacteria and have proposed membrane organization, signaling, and antioxidant roles. We discovered the plasmanylethanolamine desaturase activity that is essential for vinyl ether bond formation in a bacterial enzyme, CarF, which is a homolog of the human enzyme TMEM189. CarF mediates light-induced carotenogenesis in Myxococcus xanthus, and plasmalogens participate in sensing photooxidative stress through singlet oxygen. TMEM189 and other animal homologs could functionally replace CarF in M. xanthus, and knockout of TMEM189 in a human cell line eliminated plasmalogens. Discovery of the human plasmanylethanolamine desaturase will spur further study of plasmalogen biogenesis, functions, and roles in disease.


Subject(s)
Myxococcus xanthus/enzymology , Oxidoreductases/metabolism , Plasmalogens/biosynthesis , Ubiquitin-Conjugating Enzymes/metabolism , Animals , Bacterial Proteins/genetics , Bacterial Proteins/metabolism , Carotenoids/metabolism , Cell Line , Humans , Light , Oxidoreductases/chemistry , Oxidoreductases/genetics , Plants/enzymology , Plasmalogens/metabolism , Signal Transduction , Singlet Oxygen/metabolism , Ubiquitin-Conjugating Enzymes/chemistry , Ubiquitin-Conjugating Enzymes/genetics , Vinyl Compounds/chemistry
8.
Anim Reprod Sci ; 206: 46-59, 2019 Jul.
Article in English | MEDLINE | ID: mdl-31104948

ABSTRACT

The aim was to determine effects of maternal feed restriction in dairy goats at gestational different stages on skeletal muscle development and energy metabolism in kids at birth. Six pregnant goats were fed 50% of total digestible nutrients (TDN) and crude protein (CP) (NRC, 2007) recommendations in the first half of gestation and then fed to 100% of the recommendations in the second half of gestation (treatment R-M). In the other group, eight pregnant goats were fed 100% of TDN and CP in the first half of gestation and 50% of a restricted diet the second half of gestation (treatment M-R). Birth weight, blood glucose concentration, muscle fiber number, and size of kids at birth were not affected by maternal feed restriction. The mRNA and protein abundance of myogenic, adipogenic and fibrogenic markers were not affected (P > 0.05) by maternal diet. With regard to values for variables in kid energy metabolism, mRNA abundance of the glycolic enzyme HKII was less (P = 0.03) in the M-R group. In conclusion, maternal feed restriction in the first or second half of gestation had no affect mRNA abundance on myogenic, adipogenic, and fibrogenic markers nor were there changes in skeletal muscle mesenchymal stem cell population of kids at the time of birth. There, however, may be detrimental effects on energy metabolism by reducing HKII gene expression in skeletal muscle of dairy goat kids at the time of birth.


Subject(s)
Animal Feed/analysis , Diet/veterinary , Energy Metabolism , Goats/physiology , Muscle Development , Muscle, Skeletal/growth & development , Animal Nutritional Physiological Phenomena , Animals , Animals, Newborn , Birth Weight , Caloric Restriction , Feeding Behavior , Female , Fetal Development , Gestational Age , Maternal Nutritional Physiological Phenomena , Pregnancy
9.
Nucleic Acids Res ; 46(13): 6726-6745, 2018 07 27.
Article in English | MEDLINE | ID: mdl-29893914

ABSTRACT

Expression of CRISPR-Cas systems is a prerequisite for their defensive role against invading genetic elements. Yet, much remains unknown about how this crucial step is regulated. We describe a new mechanism controlling CRISPR-cas expression, which requires an extracytoplasmic function (ECF) σ factor (DdvS), its membrane-bound anti-σ (DdvA) and a global regulatory complex (CarD-CarG). Transcriptomic analyses revealed that the DdvS/CarD/CarG-dependent regulon comprises a type III-B CRISPR-Cas system in Myxococcus xanthus. We mapped four DdvS-driven CarD/CarG-dependent promoters, with one lying immediately upstream of the cas cluster. Consistent with direct action, DdvS and CarD-CarG localize at these promoters in vivo. The cas genes are transcribed as a polycistronic mRNA that reads through the leader into the CRISPR array, a putative σA-dependent promoter in the leader having negligible activity in vivo. Consequently, expression of the entire CRISPR-Cas system and mature CRISPR-RNA (crRNA) production is DdvS/CarD/CarG-dependent. DdvA likely uses its large C-terminal domain to sense and transduce the extracytoplasmic signal triggering CRISPR-cas expression, which we show is not starvation-induced multicellular development. An ECF-σ/anti-σ pair and a global regulatory complex provide an effective mechanism to coordinate signal-sensing with production of precursor crRNA, its processing Cas6 endoribonuclease and other Cas proteins for mature crRNA biogenesis and interference.


Subject(s)
CRISPR-Associated Proteins/genetics , CRISPR-Cas Systems , Clustered Regularly Interspaced Short Palindromic Repeats , Endoribonucleases/genetics , Gene Expression Regulation, Bacterial , Myxococcus xanthus/genetics , Sigma Factor/metabolism , Bacterial Proteins/metabolism , CRISPR-Associated Proteins/metabolism , Endoribonucleases/biosynthesis , Endoribonucleases/metabolism , Myxococcus xanthus/metabolism , Operon , Promoter Regions, Genetic , RNA, Bacterial/metabolism , Regulon , Trans-Activators/metabolism , Transcription, Genetic
10.
J Dairy Sci ; 100(6): 4435-4447, 2017 Jun.
Article in English | MEDLINE | ID: mdl-28434727

ABSTRACT

We aimed to quantify the productive and metabolic responses, and digestive changes in dairy cows fed various concentrations of soybean oil (SBO) in high-concentrate, sugarcane-based diets. Eight rumen-cannulated multiparous Holstein cows in mid lactation (574 ± 19.1 kg of body weight and 122 ± 6.9 d in milk), averaging 22.5 ± 1.22 kg/d of milk were assigned to replicated 4 × 4 Latin squares. The experimental period lasted 21 d as follows: 14 d for adaptation, followed by a sampling period from d 15 to 21. The diets were formulated with increasing concentrations of SBO [% of dry matter (DM)]: control (0%), low (LSBO; 1.57%), medium (MSBO; 4.43%), and high (HSBO; 7.34%). Dry matter intake decreased quadratically in response to SBO addition. The greatest decrease in DM intake was observed in MSBO and HSBO diets. Both milk and energy-corrected milk yield were quadratically affected by the SBO inclusion, with a slight decrease up to MSBO and substantial decrease in the HSBO diet. The milk fat concentration linearly decreased from 3.78% in the control to 3.50% in the HSBO diet. The potentially digestible neutral detergent fiber digestibility in the rumen decreased from 55.7% in the control to 35.2% in the HSBO diet. The fractional rate of digestion of potentially digestible neutral detergent fiber in the rumen decreased linearly from 3.13 to 1.39%/h from the control to HSBO diet. The fractional rate of indigestible neutral detergent fiber passage in the rumen was quadratically affected, with the lowest value (2.25%/h) for the HSBO diet. Rumen pH increased from 6.42 to 6.67, and ammonia nitrogen decreased from 28.1 to 21.4 mg/dL, in the control and HSBO diets, respectively. Rumen volatile fatty acids decreased quadratically, with the greatest decrease observed in MSBO and HSBO diets. Serum concentrations of glucose, fatty acids, and ß-hydroxybutyrate were unaffected by SBO inclusion. However, serum concentrations of total cholesterol and high- and low-density lipoproteins linearly increased with increasing concentrations of SBO in the diet. Inclusion of SBO at concentrations from 4.43 to 7.34% of the diet DM decreased DM intake, energy-corrected milk production, fiber digestibility, and rumen fermentation and was thus not recommended. Soybean oil supplementation at 1.57% of the diet DM proved to be a safe concentration for dairy cows fed high-concentrate diets with sugarcane as the sole forage.


Subject(s)
Digestion/drug effects , Eating , Lactation , Saccharum , Soybean Oil/pharmacology , 3-Hydroxybutyric Acid/metabolism , Ammonia/metabolism , Animal Feed , Animals , Blood Glucose/metabolism , Cattle , Cholesterol/blood , Digestion/physiology , Fatty Acids/analysis , Fatty Acids/metabolism , Female , Fermentation , Glycolipids , Glycoproteins , Hydrogen-Ion Concentration , Lipid Droplets , Milk/chemistry , Rumen/chemistry , Soybean Oil/administration & dosage
11.
Environ Microbiol ; 16(8): 2475-90, 2014 Aug.
Article in English | MEDLINE | ID: mdl-24428729

ABSTRACT

Extracytoplasmic function (ECF) σ factors are critical players in signal transduction networks involved in bacterial response to environmental changes. The Myxococcus xanthus genome reveals ∼45 putative ECF-σ factors, but for the overwhelming majority, the specific signals or mechanisms for selective activation and regulation remain unknown. One well-studied ECF-σ, CarQ, binds to its anti-σ, CarR, and is inactive in the dark but drives its own expression from promoter P(QRS) on illumination. This requires the CarD/CarG complex, the integration host factor (IHF) and a specific CarD-binding site upstream of P(QRS). Here, we show that DdvS, a previously uncharacterized ECF-σ, activates its own expression in a CarD/CarG-dependent manner but is inhibited when specifically bound to the N-terminal zinc-binding anti-σ domain of its cognate anti-σ, DdvA. Interestingly, we find that the autoregulatory action of 11 other ECF-σ factors studied here depends totally or partially on CarD/CarG but not IHF. In silico analysis revealed possible CarD-binding sites that may be involved in direct regulation by CarD/CarG of target promoter activity. CarD/CarG-linked ECF-σ regulation likely recurs in other myxobacteria with CarD/CarG orthologous pairs and could underlie, at least in part, the global regulatory effect of the complex on M. xanthus gene expression.


Subject(s)
Bacterial Proteins/genetics , Gene Expression Regulation, Bacterial , Genome, Bacterial , Myxococcus xanthus/genetics , Sigma Factor/genetics , Trans-Activators/genetics , Bacterial Proteins/metabolism , Base Sequence , Binding Sites , Light , Molecular Sequence Data , Myxococcus xanthus/metabolism , Promoter Regions, Genetic , Protein Binding , Sigma Factor/metabolism , Signal Transduction , Trans-Activators/metabolism , Transcription, Genetic
12.
Microbiology (Reading) ; 154(Pt 3): 895-904, 2008 Mar.
Article in English | MEDLINE | ID: mdl-18310035

ABSTRACT

Cells of the Gram-negative bacterium Myxococcus xanthus respond to blue light by producing carotenoids, pigments that play a protective role against the oxidative effects of light. Blue light triggers a network of regulatory actions that lead to the transcriptional activation of the structural genes for carotenoid synthesis. The product of carF, similar to a family of proteins of unknown function called Kua, is an early regulator of this process. Previous genetic data indicate that CarF participates in the light-dependent inactivation of the antisigma factor CarR. In the dark, CarR sequesters the ECF-sigma factor CarQ to the membrane, thereby preventing the activation of the structural genes for carotenoid synthesis. Using a bacterial two-hybrid system, we show here that both CarF and CarQ physically interact with CarR. These results, together with the finding that CarF is located at the membrane, support the hypothesis that CarF acts as an anti-antisigma factor. Comparison of CarF with other Kua proteins shows a remarkable conservation of a number of histidine residues. The effects on CarF function of several histidine to alanine substitutions and of the truncation of specific CarF domains are also reported here.


Subject(s)
Bacterial Proteins/metabolism , Carotenoids/biosynthesis , Gene Expression Regulation, Bacterial/physiology , Light , Myxococcus xanthus/metabolism , Myxococcus xanthus/physiology , Amino Acid Substitution/genetics , Artificial Gene Fusion , Cell Fractionation , Cell Membrane/chemistry , Genes, Reporter , Models, Biological , Models, Molecular , Mutagenesis, Site-Directed , Myxococcus xanthus/radiation effects , Protein Binding , Protein Interaction Mapping , Sequence Deletion , Two-Hybrid System Techniques , beta-Galactosidase/genetics , beta-Galactosidase/metabolism
13.
Mol Microbiol ; 56(5): 1159-68, 2005 Jun.
Article in English | MEDLINE | ID: mdl-15882411

ABSTRACT

Copper induces a red pigmentation in cells of the bacterium Myxococcus xanthus when they are incubated in the dark, at suboptimal growth conditions. The colouration results from the accumulation of carotenoids, as demonstrated by chemical analysis, and by the lack of a copper effect on M. xanthus mutants affected in known structural genes for carotenoid synthesis. None of several other metals or oxidative agents can mimic the copper effect on carotenoid synthesis. Until now, blue light was the only environmental agent known to induce carotenogenesis in M. xanthus. As happens for the blue light, copper activates the transcription of the structural genes for carotenoid synthesis through the transcriptional activation of the carQRS operon. This encodes the ECF sigma factor CarQ, directly or indirectly responsible for the activation of the structural genes, and the anti-sigma factor CarR, which physically interacts with CarQ to blocks its action in the absence of external stimuli. All but one of the other regulatory elements known to participate in the induction of carotenoid synthesis by blue light are required for the response to copper. The exception is CarF, a protein required for the light-mediated dismantling of the CarR-CarQ complex. In addition to carotenogenesis, copper induces other unknown cellular mechanisms that confer tolerance to the metal.


Subject(s)
Carotenoids/biosynthesis , Copper/pharmacology , Gene Expression Regulation, Bacterial , Myxococcus xanthus/metabolism , Anti-Bacterial Agents/pharmacology , Drug Resistance, Bacterial , Genes, Bacterial/drug effects , Light , Myxococcus xanthus/drug effects , Myxococcus xanthus/genetics , Operon/drug effects , Pigments, Biological/biosynthesis , Sigma Factor/physiology , Transcription, Genetic
14.
Genetics ; 167(4): 1585-95, 2004 Aug.
Article in English | MEDLINE | ID: mdl-15342500

ABSTRACT

CarD is the only reported prokaryotic protein showing structural and functional features typical of eukaryotic high-mobility group A transcription factors. In prokaryotes, proteins similar to CarD appear to be confined primarily to myxobacteria. In Myxococcus xanthus, CarD has been previously shown to act as a positive element in two different regulatory networks: one for light-induced synthesis of carotenoids and the other for starvation-induced fruiting body formation. We have now tested the effect of a loss-of-function mutation in the carD gene (carD1) on the expression of a random collection of lacZ-tagged genes, which are normally expressed in the dark during vegetative growth in rich medium. Our results indicate that CarD plays a significant role in the transcriptional regulation of various indicated genes. The carD1 mutation downregulates some genes and upregulates others. Also reported here is the isolation of several mutations that suppress the strong effect of carD1 on the expression of a particular vegetative gene. One of them (sud-2) also suppresses the effect of carD1 on other vegetative genes and on fruiting-body formation. Thus, CarD and the sud-2 gene product appear to participate in a single mechanism, which underlies various apparently diverse regulatory phenomena ascribed to CarD.


Subject(s)
Bacterial Proteins/genetics , Genes, Bacterial , Myxococcus xanthus/genetics , Trans-Activators/genetics , Amino Acid Sequence , Bacteriophages/genetics , Genotype , Kinetics , Molecular Sequence Data , Mutagenesis, Insertional , Phenotype , Promoter Regions, Genetic , Sequence Alignment , Sequence Homology, Amino Acid , Transcription, Genetic/genetics
15.
Mol Microbiol ; 49(3): 769-81, 2003 Aug.
Article in English | MEDLINE | ID: mdl-12864858

ABSTRACT

Myxococcus xanthus, a member of the Proteobacteria delta-class, has two independent recA genes, recA1 and recA2, but only recA2 is DNA damage-inducible. The lexA gene has been isolated from M. xanthus by PCR amplification with oligonucleotides designed after sequence identification by tblastn analysis of its genome at the Cereon Microbial Sequence Database. The M. xanthus purified LexA protein is shown to bind specifically to the consensus sequence CTRHAMRYBYGTTCAGS present upstream of lexA and recA2. A degenerate copy of this motif but with important differences can be identified in the region upstream of the recA1 gene. A knock-out lexA(Def) mutant that has been generated does not differ significantly from wild type in morphology, growth rate, light-induced carotenogenesis or development. Using transcriptional lacZ fusions and quantitative RT-PCR analysis, it has been demonstrated that expression of both lexA and recA2 genes is constitutive in the lexA(Def) mutant, whereas the transcription of the DNA damage non-inducible recA1 gene is not affected in this strain. recN and ssb, whose expression in Escherichia coli are LexA-regulated, are induced by DNA damage in the M. xanthus lexA(Def) mutant. These data reveal the existence of different regulatory mechanisms for DNA damage-inducible genes in bacteria belonging to different phyla.


Subject(s)
Bacterial Proteins/genetics , DNA Damage , DNA, Bacterial/genetics , Gene Expression Regulation, Bacterial , Myxococcus xanthus/genetics , Serine Endopeptidases/genetics , Bacterial Proteins/biosynthesis , Bacterial Proteins/physiology , Base Sequence , Cloning, Molecular , Consensus Sequence , DNA-Binding Proteins/genetics , DNA-Binding Proteins/physiology , Genes, Bacterial , Molecular Sequence Data , Myxococcus xanthus/drug effects , Polymerase Chain Reaction , Protein Binding , SOS Response, Genetics , Serine Endopeptidases/biosynthesis , Serine Endopeptidases/physiology , Transcription, Genetic
16.
Mol Microbiol ; 47(2): 561-71, 2003 Jan.
Article in English | MEDLINE | ID: mdl-12519205

ABSTRACT

Myxococcus xanthus cells respond to blue light by producing carotenoids. Light triggers a network of regulatory actions that lead to the transcriptional activation of the carotenoid genes. By screening the colour phenotype of a collection of Tn5-lac insertion mutants, we have isolated a new mutant devoid of carotenoid synthesis. We map the transposon insertion, which co-segregates with the mutant phenotype, to a previously unknown gene designated here as carF. An in frame deletion within carF causes the same phenotype as the Tn5-lac insertion. The carF deletion prevents the activation of the normally light-inducible genes, without affecting the expression of any of the regulatory genes known to be expressed in a light-independent manner. Until now, the switch that sets off the regulatory cascade had been identified with light-driven inactivation of protein CarR, an antisigma factor. The exact mechanism of this inactivation has remained elusive. We show by epistatic analysis that the carF gene product participates in the light-dependent inactivation of CarR. The predicted CarF amino acid sequence reveals no known prokaryotic homologues. On the other hand, CarF is remarkably similar to Kua, a family of proteins of unknown function that is widely distributed among eukaryotes.


Subject(s)
Bacterial Proteins/metabolism , Carotenoids/biosynthesis , Gene Expression Regulation, Bacterial , Genes, Regulator , Light , Myxococcus xanthus/metabolism , Amino Acid Sequence , Amino Acid Substitution , Bacterial Proteins/genetics , Cloning, Molecular , DNA Transposable Elements/genetics , Gene Deletion , Molecular Sequence Data , Myxococcus xanthus/genetics , Sequence Analysis, DNA
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