scholarly journals A Conserved Histidine in Cytochrome c Maturation Permease CcmB of Shewanella putrefaciens Is Required for Anaerobic Growth below a Threshold Standard Redox Potential

2006 ◽  
Vol 189 (3) ◽  
pp. 1036-1043 ◽  
Author(s):  
Jason R. Dale ◽  
Roy Wade ◽  
Thomas J. DiChristina
Keyword(s):  
Electron Acceptor ◽  
Type Strain ◽  
Wild Type Strain ◽  
Shewanella Putrefaciens ◽  
Electron Acceptors ◽  
Anaerobic Growth ◽  
Histidine Residue ◽  
Wild Type ◽  
Standard Redox Potential ◽  
Wide Range

ABSTRACT Shewanella putrefaciens strain 200 respires a wide range of compounds as terminal electron acceptor. The respiratory versatility of Shewanella is attributed in part to a set of c-type cytochromes with widely varying midpoint redox potentials (E′0). A point mutant of S. putrefaciens, originally designated Urr14 and here renamed CCMB1, was found to grow at wild-type rates on electron acceptors with high E′0 [O2, NO3 −, Fe(III) citrate, MnO2, and Mn(III) pyrophosphate] yet was severely impaired for growth on electron acceptors with low E′0 [NO2 −, U(VI), dimethyl sulfoxide, TMAO (trimethylamine N-oxide), fumarate, γ-FeOOH, SO3 2−, and S2O3 2−]. Genetic complementation and nucleotide sequence analyses indicated that the CCMB1 respiratory mutant phenotype was due to mutation of a conserved histidine residue (H108Y) in a protein that displayed high homology to Escherichia coli CcmB, the permease subunit of an ABC transporter involved in cytochrome c maturation. Although CCMB1 retained the ability to grow on electron acceptors with high E′0, the cytochrome content of CCMB1 was <10% of that of the wild-type strain. Periplasmic extracts of CCMB1 contained slightly greater concentrations of the thiol functional group (-SH) than did the wild-type strain, an indication that the Eh of the CCMB1 periplasm was abnormally low. A ccmB deletion mutant was unable to respire anaerobically on any electron acceptor, yet retained aerobic respiratory capability. These results suggest that the mutation of a conserved histidine residue (H108) in CCMB1 alters the redox homeostasis of the periplasm during anaerobic growth on electron acceptors with low (but not high) E′0. This is the first report of the effects of Ccm deficiencies on bacterial respiration of electron acceptors whose E′0 nearly span the entire redox continuum.

scholarly journals A Mutation in the 3-Phosphoglycerate Kinase Gene Allows Anaerobic Growth of Bacillus subtilis in the Absence of ResE Kinase

1999 ◽  
Vol 181 (22) ◽  
pp. 7087-7097 ◽  
Author(s):  
Michiko M. Nakano ◽  
Yi Zhu ◽  
Koki Haga ◽  
Hirofumi Yoshikawa ◽  
Abraham L. Sonenshein ◽  
...  
Keyword(s):  
Bacillus Subtilis ◽  
Type Strain ◽  
Wild Type Strain ◽  
Response Regulator ◽  
Anaerobic Respiration ◽  
Phosphoglycerate Kinase ◽  
Anaerobic Growth ◽  
Wild Type ◽  
Kinase Gene ◽  
Glycolytic Intermediate

ABSTRACT The Bacillus subtilis ResD-ResE two-component signal transduction system is essential for aerobic and anaerobic respiration. A spontaneous suppressor mutant that expresses ResD-controlled genes and grows anaerobically in the absence of the ResE histidine kinase was isolated. In addition, aerobic expression of ResD-controlled genes in the suppressed strain was constitutive and occurred at a much higher level than that observed in the wild-type strain. The suppressing mutation, which mapped to pgk, the gene encoding 3-phosphoglycerate kinase, failed to suppress a resDmutation, suggesting that the suppressing mutation creates a pathway for phosphorylation of the response regulator, ResD, which is independent of the cognate sensor kinase, ResE. The pgk-1mutant exhibited very low but measurable 3-phosphoglycerate kinase activity compared to the wild-type strain. The results suggest that accumulation of a glycolytic intermediate, probably 1,3-diphosphoglycerate, is responsible for the observed effect of thepgk-1 mutation on anaerobiosis of resE mutant cells.

scholarly journals Cell-to-Cell Signaling in Xylella fastidiosa Suppresses Movement and Xylem Vessel Colonization in Grape

2008 ◽  
Vol 21 (10) ◽  
pp. 1309-1315 ◽  
Author(s):  
Subhadeep Chatterjee ◽  
Karyn L. Newman ◽  
Steven E. Lindow
Keyword(s):  
Cell Signaling ◽  
Type Strain ◽  
Laser Scanning ◽  
Wild Type Strain ◽  
Xylella Fastidiosa ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Deficient Mutant ◽  
Wild Type ◽  
Wide Range

Cell-to-cell signaling mediated by a fatty acid diffusible signaling factor (DSF) is central to the regulation of the virulence of Xylella fastidiosa. DSF production by X. fastidiosa is dependent on rpfF and, although required for insect colonization, appears to reduce its virulence to grape. To understand what aspects of colonization of grape are controlled by DSF in X. fastidiosa and, thus, those factors that contribute to virulence, we assessed the colonization of grape by a green fluorescent protein–marked rpfF-deficient mutant. The rpfF-deficient mutant was detected at a greater distance from the point of inoculation than the wild-type strain at a given sampling time, and also attained a population size that was up to 100-fold larger than that of the wild-type strain at a given distance from the point of inoculation. Confocal laser-scanning microscopy revealed that approximately 10-fold more vessels in petioles of symptomatic leaves harbored at least some cells of either the wild type or rpfF mutant when compared with asymptomatic leaves and, thus, that disease symptoms were associated with the extent of vessel colonization. Importantly, the rpfF mutant colonized approximately threefold more vessels than the wild-type strain. Although a wide range of colony sizes were observed in vessels colonized by both the wild type and rpfF mutant, the proportion of colonized vessels harboring large numbers of cells was significantly higher in plants inoculated with the rpfF mutant than with the wild-type strain. These studies indicated that the hypervirulence phenotype of the rpfF mutant is due to both a more extensive spread of the pathogen to xylem vessels and unrestrained multiplication within vessels leading to blockage. These results suggest that movement and multiplication of X. fastidiosa in plants are linked, perhaps because cell wall degradation products are a major source of nutrients. Thus, DSF-mediated cell-to-cell signaling, which restricts movement and colonization of X. fastidiosa, may be an adaptation to endophytic growth of the pathogen that prevents the excessive growth of cells in vessels.

The dependence of Escherichia coli asparaginase II formation on cyclic AMP and cyclic AMP receptor protein

1978 ◽  
Vol 24 (5) ◽  
pp. 629-631 ◽  
Author(s):  
La Verne Russell ◽  
Hiroshi Yamazaki
Keyword(s):  
Escherichia Coli ◽  
Cyclic Amp ◽  
Type Strain ◽  
Wild Type Strain ◽  
Anaerobic Growth ◽  
Receptor Protein ◽  
Wild Type ◽  
Cyclic Amp Receptor Protein ◽  
E Coli ◽  
Cyclic Amp Synthesis

The amount of asparaginase II in an Escherichia coli wild-type strain (cya+, crp+) markedly increased upon a shift from aerobic to anaerobic growth. However, no such increase occurred in a mutant (cya) lacking cyclic AMP synthesis unless supplemented with exogenous cyclic AMP. Since a mutant (crp) deficient in cyclic AMP receptor protein also did not support the anaerobic formation of this enzyme, it is concluded that the formation of E. coli asparaginase II depends on both cyclic AMP and cyclic AMP receptor protein.

scholarly journals Mycobacterium smegmatisl-Alanine Dehydrogenase (Ald) Is Required for Proficient Utilization of Alanine as a Sole Nitrogen Source and Sustained Anaerobic Growth

2002 ◽  
Vol 184 (18) ◽  
pp. 5001-5010 ◽  
Author(s):  
Zhengyu Feng ◽  
Nancy E. Cáceres ◽  
Gautam Sarath ◽  
Raúl G. Barletta
Keyword(s):  
Enzyme Activity ◽  
Nitrogen Source ◽  
Type Strain ◽  
Growth Stage ◽  
Reductive Amination ◽  
Wild Type Strain ◽  
Anaerobic Growth ◽  
Sole Nitrogen Source ◽  
Wild Type ◽  
Anaerobic Conditions

ABSTRACT NAD(H)-dependent l-alanine dehydrogenase (EC 1.4.1.1) (Ald) catalyzes the oxidative deamination of l-alanine and the reductive amination of pyruvate. To assess the physiological role of Ald in Mycobacterium smegmatis, we cloned the ald gene, identified its promoter, determined the protein expression levels, and analyzed the combined effects of nutrient supplementation, oxygen availability, and growth stage on enzyme activity. High Ald activities were observed in cells grown in the presence of l- or d-alanine regardless of the oxygen availability and growth stage. In exponentially growing cells under aerobic conditions, supplementation with alanine resulted in a 25- to 50-fold increase in the enzyme activity. In the absence of alanine supplementation, 23-fold-higher Ald activities were observed in cells grown exponentially under anaerobic conditions. Furthermore, M. smegmatis ald null mutants were constructed by targeted disruption and were shown to lack any detectable Ald activity. In contrast, the glycine dehydrogenase (EC 1.4.1.10) (Gdh) activity in mutant cells remained at wild-type levels, indicating that another enzyme protein is responsible for the physiologically relevant reductive amination of glyoxylate. The ald mutants grew poorly in minimal medium with l-alanine as the sole nitrogen source, reaching a saturation density 100-fold less than that of the wild-type strain. Likewise, mutants grew to a saturation density 10-fold less than that of the wild-type strain under anaerobic conditions. In summary, the phenotypes displayed by the M. smegmatis ald mutants suggest that Ald plays an important role in both alanine utilization and anaerobic growth.

scholarly journals Transcriptional and Proteomic Analysis of a Ferric Uptake Regulator (Fur) Mutant of Shewanella oneidensis: Possible Involvement of Fur in Energy Metabolism, Transcriptional Regulation, and Oxidative Stress

2002 ◽  
Vol 68 (2) ◽  
pp. 881-892 ◽  
Author(s):  
Dorothea K. Thompson ◽  
Alexander S. Beliaev ◽  
Carol S. Giometti ◽  
Sandra L. Tollaksen ◽  
Tripti Khare ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Transcriptional Regulation ◽  
Energy Metabolism ◽  
Type Strain ◽  
Wild Type Strain ◽  
Shewanella Oneidensis ◽  
Anaerobic Growth ◽  
Ferric Uptake Regulator ◽  
Wild Type ◽  
And Oxidative Stress

ABSTRACT The iron-directed, coordinate regulation of genes depends on the fur (ferric uptake regulator) gene product, which acts as an iron-responsive, transcriptional repressor protein. To investigate the biological function of a fur homolog in the dissimilatory metal-reducing bacterium Shewanella oneidensis MR-1, a fur knockout strain (FUR1) was generated by suicide plasmid integration into this gene and characterized using phenotype assays, DNA microarrays containing 691 arrayed genes, and two-dimensional polyacrylamide gel electrophoresis. Physiological studies indicated that FUR1 was similar to the wild-type strain when they were compared for anaerobic growth and reduction of various electron acceptors. Transcription profiling, however, revealed that genes with predicted functions in electron transport, energy metabolism, transcriptional regulation, and oxidative stress protection were either repressed (ccoNQ, etrA, cytochrome b and c maturation-encoding genes, qor, yiaY, sodB, rpoH, phoB, and chvI) or induced (yggW, pdhC, prpC, aceE, fdhD, and ppc) in the fur mutant. Disruption of fur also resulted in derepression of genes (hxuC, alcC, fhuA, hemR, irgA, and ompW) putatively involved in iron uptake. This agreed with the finding that the fur mutant produced threefold-higher levels of siderophore than the wild-type strain under conditions of sufficient iron. Analysis of a subset of the FUR1 proteome (i.e., primarily soluble cytoplasmic and periplasmic proteins) indicated that 11 major protein species reproducibly showed significant (P < 0.05) differences in abundance relative to the wild type. Protein identification using mass spectrometry indicated that the expression of two of these proteins (SodB and AlcC) correlated with the microarray data. These results suggest a possible regulatory role of S. oneidensis MR-1 Fur in energy metabolism that extends the traditional model of Fur as a negative regulator of iron acquisition systems.

scholarly journals Growth of Campylobacter jejuni Supported by Respiration of Fumarate, Nitrate, Nitrite, Trimethylamine-N-Oxide, or Dimethyl Sulfoxide Requires Oxygen

2002 ◽  
Vol 184 (15) ◽  
pp. 4187-4196 ◽  
Author(s):  
Michael J. Sellars ◽  
Stephen J. Hall ◽  
David J. Kelly
Keyword(s):  
Energy Conservation ◽  
Dimethyl Sulfoxide ◽  
Campylobacter Jejuni ◽  
Electron Acceptor ◽  
Electron Acceptors ◽  
Anaerobic Growth ◽  
Strictly Anaerobic ◽  
Anaerobic Conditions ◽  
Single Class ◽  
Wide Range

ABSTRACT The human gastrointestinal pathogen Campylobacter jejuni is a microaerophilic bacterium with a respiratory metabolism. The genome sequence of C. jejuni strain 11168 reveals the presence of genes that encode terminal reductases that are predicted to allow the use of a wide range of alternative electron acceptors to oxygen, including fumarate, nitrate, nitrite, and N- or S-oxides. All of these reductase activities were present in cells of strain 11168, and the molybdoenzyme encoded by Cj0264c was shown by mutagenesis to be responsible for both trimethylamine-N-oxide (TMAO) and dimethyl sulfoxide (DMSO) reduction. Nevertheless, growth of C. jejuni under strictly anaerobic conditions (with hydrogen or formate as electron donor) in the presence of any of the electron acceptors tested was insignificant. However, when fumarate, nitrate, nitrite, TMAO, or DMSO was added to microaerobic cultures in which the rate of oxygen transfer was severely restricted, clear increases in both the growth rate and final cell density compared to what was seen with the control were obtained, indicative of electron acceptor-dependent energy conservation. The C. jejuni genome encodes a single class I-type ribonucleotide reductase (RNR) which requires oxygen to generate a tyrosyl radical for catalysis. Electron microscopy of cells that had been incubated under strictly anaerobic conditions with an electron acceptor showed filamentation due to an inhibition of cell division similar to that induced by the RNR inhibitor hydroxyurea. An oxygen requirement for DNA synthesis can thus explain the lack of anaerobic growth of C. jejuni. The results indicate that strict anaerobiosis is a stress condition for C. jejuni but that alternative respiratory pathways can contribute significantly to energy conservation under oxygen-limited conditions, as might be found in vivo.

scholarly journals Oxygen Regulation of the ccoN Gene Encoding a Component of the cbb3 Oxidase inRhodobacter sphaeroides 2.4.1T: Involvement of the FnrL Protein

1998 ◽  
Vol 180 (8) ◽  
pp. 2228-2231 ◽  
Author(s):  
Nigel J. Mouncey ◽  
Samuel Kaplan
Keyword(s):  
Rhodobacter Sphaeroides ◽  
Type Strain ◽  
Wild Type Strain ◽  
Growth Conditions ◽  
Anaerobic Growth ◽  
Wild Type ◽  
Transcriptional Fusion ◽  
Gene Encoding ◽  
Genes Encoding ◽  
In The Wild

ABSTRACT The ccoNOQP gene cluster of Rhodobacter sphaeroides 2.4.1T encodes acbb 3 cytochrome oxidase which is utilized in oxygen-limited conditions for aerobic respiration. The β-galactosidase activity of accoN::lacZ transcriptional fusion was low under high (30%)-oxygen and anaerobic growth conditions. Maximal ccoN::lacZexpression was observed when the oxygen concentration was lowered to 2%. In an FnrL mutant,ccoN::lacZ expression was significantly lower than in the wild-type strain, suggesting that FnrL is a positive regulator of genes encoding thecbb 3 oxidase.

scholarly journals Effects of Mutations of RAD50, RAD51, RAD52, and Related Genes on Illegitimate Recombination in Saccharomyces cerevisiae

Genetics ◽  
1996 ◽  
Vol 142 (2) ◽  
pp. 383-391 ◽  
Author(s):  
Yasumasa Tsukamoto ◽  
Jun-ichi Kato ◽  
Hideo Ikeda
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Quantitative Analysis ◽  
Structural Analysis ◽  
Recombination Rate ◽  
Type Strain ◽  
Negative Selection ◽  
Wild Type Strain ◽  
Illegitimate Recombination ◽  
Wild Type ◽  
In The Wild

Abstract To examine the mechanism of illegitimate recombination in Saccharomyces cerevisiae, we have developed a plasmid system for quantitative analysis of deletion formation. A can1 cyh2 cell carrying two negative selection markers, the CAN1 and CYH2 genes, on a YCp plasmid is sensitive to canavanine and cycloheximide, but the cell becomes resistant to both drugs when the plasmid has a deletion over the CAN1 and CYH2 genes. Structural analysis of the recombinant plasmids obtained from the resistant cells showed that the plasmids had deletions at various sites of the CAN1-CYH2 region and there were only short regions of homology (1-5 bp) at the recombination junctions. The results indicated that the deletion detected in this system were formed by illegitimate recombination. Study on the effect of several rad mutations showed that the recombination rate was reduced by 30-, 10-, 10-, and 10-fold in the rad52, rad50, mre11, and xrs2 mutants, respectively, while in the rud51, 54, 55, and 57 mutants, the rate was comparable to that in the wild-type strain. The rad52 mutation did not affect length of homology at junction sites of illegitimate recombination.

scholarly journals The role of Zur-regulated lipoprotein A in bacterial morphology, antimicrobial susceptibility, and production of outer membrane vesicles in Acinetobacter baumannii

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Nayeong Kim ◽  
Hyo Jeong Kim ◽  
Man Hwan Oh ◽  
Se Yeon Kim ◽  
Mi Hyun Kim ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Outer Membrane ◽  
Mutant Strain ◽  
Antimicrobial Susceptibility ◽  
Type Strain ◽  
Wild Type Strain ◽  
Membrane Vesicles ◽  
Outer Membrane Vesicles ◽  
Wild Type ◽  
Bacterial Morphology

Abstract Background Zinc uptake-regulator (Zur)-regulated lipoprotein A (ZrlA) plays a role in bacterial fitness and overcoming antimicrobial exposure in Acinetobacter baumannii. This study further characterized the zrlA gene and its encoded protein and investigated the roles of the zrlA gene in bacterial morphology, antimicrobial susceptibility, and production of outer membrane vesicles (OMVs) in A. baumannii ATCC 17978. Results In silico and polymerase chain reaction analyses showed that the zrlA gene was conserved among A. baumannii strains with 97–100% sequence homology. Recombinant ZrlA protein exhibited a specific enzymatic activity of D-alanine-D-alanine carboxypeptidase. Wild-type A. baumannii exhibited more morphological heterogeneity than a ΔzrlA mutant strain during stationary phase. The ΔzrlA mutant strain was more susceptible to gentamicin than the wild-type strain. Sizes and protein profiles of OMVs were similar between the wild-type and ΔzrlA mutant strains, but the ΔzrlA mutant strain produced 9.7 times more OMV particles than the wild-type strain. OMVs from the ΔzrlA mutant were more cytotoxic in cultured epithelial cells than OMVs from the wild-type strain. Conclusions The present study demonstrated that A. baumannii ZrlA contributes to bacterial morphogenesis and antimicrobial resistance, but its deletion increases OMV production and OMV-mediated host cell cytotoxicity.

scholarly journals FixJ family regulator AcfR of Azorhizobium caulinodans is involved in symbiosis with the host plant

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Wei Liu ◽  
Xue Bai ◽  
Yan Li ◽  
Haikun Zhang ◽  
Xiaoke Hu
Keyword(s):  
Signal Transduction ◽  
Host Plant ◽  
Type Strain ◽  
Wild Type Strain ◽  
Response Regulator ◽  
Azorhizobium Caulinodans ◽  
Wild Type ◽  
Response Regulators ◽  
Free Living ◽  
Two Component

Abstract Background A wide variety of bacterial adaptative responses to environmental conditions are mediated by signal transduction pathways. Two-component signal transduction systems are one of the predominant means used by bacteria to sense the signals of the host plant and adjust their interaction behaviour. A total of seven open reading frames have been identified as putative two-component response regulators in the gram-negative nitrogen-fixing bacteria Azorhizobium caulinodans ORS571. However, the biological functions of these response regulators in the symbiotic interactions between A. caulinodans ORS571 and the host plant Sesbania rostrata have not been elucidated to date. Results In this study, we identified and investigated a two-component response regulator, AcfR, with a phosphorylatable N-terminal REC (receiver) domain and a C-terminal HTH (helix-turn-helix) LuxR DNA-binding domain in A. caulinodans ORS571. Phylogenetic analysis showed that AcfR possessed close evolutionary relationships with NarL/FixJ family regulators. In addition, six histidine kinases containing HATPase_c and HisKA domains were predicted to interact with AcfR. Furthermore, the biological function of AcfR in free-living and symbiotic conditions was elucidated by comparing the wild-type strain and the ΔacfR mutant strain. In the free-living state, the cell motility behaviour and exopolysaccharide production of the ΔacfR mutant were significantly reduced compared to those of the wild-type strain. In the symbiotic state, the ΔacfR mutant showed a competitive nodule defect on the stems and roots of the host plant, suggesting that AcfR can provide A. caulinodans with an effective competitive ability for symbiotic nodulation. Conclusions Our results showed that AcfR, as a response regulator, regulates numerous phenotypes of A. caulinodans under the free-living conditions and in symbiosis with the host plant. The results of this study help to elucidate the involvement of a REC + HTH_LuxR two-component response regulator in the Rhizobium-host plant interaction.

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