Abstract:
:Because the ferric uptake regulator (fur) appears to be an essential gene in Pseudomonas aeruginosa, resistance to manganese was used as an enrichment to isolate strains carrying point mutations in the fur gene in order to assess its role in the co-ordinate expression of siderophores and exotoxin A (ETA). This report describes a detailed molecular and phenotypic characterization of four mutants and one revertant, which carry point mutations in the fur gene. Two parental strains were used in this study. Three mutants were isolated from the widely used strain, PAO1. One of these, CS (cold sensitive), has a mutation in the 5' non-coding region of the fur gene while the two other mutants derived from this parent have mutations resulting in the following deduced changes in Fur: mutant A2, H86-->R; mutant A4, H86-->Y. The other mutant (C6) and its revertant (C6Rv) were derived from PAO6261, a mutant of PAO1 with a deletion in the anr gene (anaerobic regulation of arginine deiminase and nitrate reduction) that controls anaerobic respiration in P. aeruginosa. Fur from the C6 mutant has an A10-->G mutation while in the C6Rv spontaneous revertant the mutant Gly residue has been changed to Ser at this position. All mutants were examined for alterations in the iron-regulated expression of siderophores and ETA. The A2 and A4 mutants expressed higher levels of siderophores in iron-deficient media and in iron-replete media. The CS mutant constitutively expressed siderophores at 25 degrees C. At 42 degrees C siderophore biosynthesis was iron repressed as in the parental strain PAO1. The deletion of anr in PAO6261 had no apparent effect on the iron-mediated regulation of siderophore synthesis, but the C6 mutant derived from this strain produces siderophores constitutively. The iron-regulated production of siderophores by C6Rv was similar to the parental strain PAO6261 and PAO1. Because one of the parental strains used in this study is an Anr mutant, regulation of ETA production was assessed under aerobic and microaerobic conditions. Iron-dependent repression of ETA synthesis in both parental strains and A2 and A4 mutants was found to be 50-100-fold under aerobic and microaerobic conditions, as assayed by quantitative Western dot-blot assays. By contrast in the CS and C6 mutants, while iron-dependent repression os ETA synthesis was similar to both parental strains under aerobic conditions, ETA production in these mutants was constitutive in a microaerobic environment. RNase protection analysis of toxA and regAB transcription in PAO1, PAO6261 and the C6 mutant corroborated the results of quantitative dot-blot assays of ETA. The mutant Fur proteins were purified and examined for their ability to bind to the promoter of a gene (pvdS) that positively regulates the expression of siderophores and ETA. Fur from the A2 and A4 mutants and from the C6Rv revertant was able to bind to the target DNA, but with reduced affinity by comparison to wild-type Fur. Fur from the C6 mutant in DNase I footprint experiments failed to protect the promoter region of the pvdS gene, but it retained some weak binding activity in gel mobility shift assays. The data presented in this study not only furnish some additional insights into the structure-function relationships of Fur, but also afford novel perspectives of virulence factors in P. aeruginosa under environmental conditions that have not previously been considered.
journal_name
Mol Microbioljournal_title
Molecular microbiologyauthors
Barton HA,Johnson Z,Cox CD,Vasil AI,Vasil MLdoi
10.1046/j.1365-2958.1996.381426.xsubject
Has Abstractpub_date
1996-09-01 00:00:00pages
1001-17issue
5eissn
0950-382Xissn
1365-2958journal_volume
21pub_type
杂志文章abstract::Only few small, regulatory RNAs encoded opposite another gene have been identified in bacteria. Here, we report the characterization of a locus where a small RNA (SymR) is encoded in cis to an SOS-induced gene whose product shows homology to the antitoxin MazE (SymE). Synthesis of the SymE protein is tightly repressed...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1111/j.1365-2958.2007.05688.x
更新日期:2007-05-01 00:00:00
abstract::Natural transformation is a potent driver for genetic diversification in bacterial populations. It involves exogenous DNA binding, uptake, transport and internalization into the cytoplasm, where DNA can be processed and integrated into the host chromosome. Direct visualisation of transforming DNA (tDNA) has been limit...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1111/mmi.13440
更新日期:2016-09-01 00:00:00
abstract::Colonization of mucosal respiratory surfaces is a prerequisite for the human pathobiont Streptococcus pneumoniae (the pneumococcus) to cause severe invasive infections. The arsenal of pneumococcal adhesins interacts with a multitude of extracellular matrix proteins. A paradigm for pneumococci is their interaction with...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1111/mmi.13740
更新日期:2017-09-01 00:00:00
abstract::Cloning and sequencing of the IgA1 protease gene (iga) from Neisseria meningitidis strain HF13 showed an overall structure equivalent to iga genes from Neisseria gonorrhoeae and Haemophilus influenzae, although no region corresponding to the gonococcal alpha-peptide was evident. An additional 18 N. meningitidis and 3 ...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1111/j.1365-2958.1995.tb02263.x
更新日期:1995-02-01 00:00:00
abstract::A 1.3 kb cDNA (cDNA52) was derived from Trypanosoma cruzi trypomastigote mRNA. Using single stranded probes in Northern blots, we identified the putative coding strand of cDNA52. In addition, a minor band was detected in RNA from epimastigotes that was absent in RNA from trypomastigotes. Nucleotide sequence analysis r...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1111/j.1365-2958.1991.tb01841.x
更新日期:1991-01-01 00:00:00
abstract::The cyclic AMP protein kinase A pathway governs numerous biological features of the fungal pathogen Candida albicans. The catalytic protein kinase A subunits, Tpk1 (orf19.4892) and Tpk2 (orf19.2277), have divergent roles, and most studies indicate a more pronounced role for Tpk2. Here we dissect two Tpk1-responsive pr...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1111/j.1365-2958.2012.08193.x
更新日期:2012-10-01 00:00:00
abstract::Listeria monocytogenes is an intracellular bacterial pathogen that expresses several surface proteins critical for the infectious process. Such proteins include InlA (internalin) and InlB, involved in bacterial entry into the host cell, and ActA, required for bacterially induced actin-based motility. Although the mole...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1046/j.1365-2958.1997.4621825.x
更新日期:1997-07-01 00:00:00
abstract::A method of insertional mutagenesis for naturally transformable organisms has been adapted from Haemophilus influenzae and applied to the study of the pathogenesis of Campylobacter jejuni. A series of kanamycin-resistant insertional mutants of C. jejuni 81-176 has been generated and screened for loss of ability to inv...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1111/j.1365-2958.1994.tb01324.x
更新日期:1994-12-01 00:00:00
abstract::Protein kinase G of Mycobacterium tuberculosis has been implicated in virulence and in regulation of glutamate metabolism. Here we show that this kinase undergoes a pattern of autophosphorylation that is distinct from that of other M. tuberculosis protein kinases characterized to date and we identify GarA as a substra...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1111/j.1365-2958.2008.06489.x
更新日期:2008-12-01 00:00:00
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journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1111/j.1365-2958.2012.07971.x
更新日期:2012-02-01 00:00:00
abstract::Filamentous hemagglutinin (FHA) is a critically important virulence factor produced by Bordetella species that cause respiratory infections in humans and other animals. It is also a prototypical member of the widespread two partner secretion (TPS) pathway family of proteins. First synthesized as a ~370 kDa protein cal...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1111/mmi.14318
更新日期:2019-09-01 00:00:00
abstract::The tetA(L) gene of Bacillus subtilis encodes a transmembrane protein that can function as a Tc-metal/H+ antiporter, conferring low-level resistance to tetracycline. The TetA(L) coding sequence is preceded by a leader region that contains a 20-amino-acid open reading frame and an appropriately spaced ribosome binding ...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1046/j.1365-2958.1998.01119.x
更新日期:1998-12-01 00:00:00
abstract::The cer-Xer dimer resolution system of plasmid ColE1 is highly selective, acting only at sites on the same molecule and in direct repeat. Recombination requires the XerCD recombinase and accessory proteins ArgR and PepA. The Escherichia coli chromosome dimer resolution site dif and the type II hybrid site use the same...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1046/j.1365-2958.1996.5471072.x
更新日期:1996-05-01 00:00:00
abstract::We have followed the time-dependent transfection of Paramecium cells with a vector containing the gene of green fluorescent protein (GFP) attached to the C-terminus of the PtSERCA1 gene. The outlines of alveolar sacs (ASs) are labelled, as is the endoplasmic reticulum (ER) throughout the cell. When GFP fluorescence is...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1046/j.1365-2958.2000.02038.x
更新日期:2000-08-01 00:00:00
abstract::Many fungi undergo a morphological transition to filamentous growth in response to limiting nutrient conditions. Constitutively elongated Saccharomyces cerevisiae mutants (elm) have been isolated; the ELM1 gene encodes a putative serine/threonine protein kinase. A novel allele, elm1-15, has been isolated in an S288C-d...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1046/j.1365-2958.1997.6231990.x
更新日期:1997-11-01 00:00:00
abstract::The opportunistic pathogen Pseudomonas aeruginosa produces type 4 fimbriae which promote adhesion to epithelial cells and are associated with a form of surface translocation called twitching motility. Transposon mutagenesis was used to identify loci required for fimbrial assembly or function by screening for mutants t...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1111/j.1365-2958.1995.tb02414.x
更新日期:1995-05-01 00:00:00
abstract::The fungal pathogen Candida albicans can transition from budding to hyphal growth, which promotes biofilm formation and invasive growth into tissues. Stimulation of adenylyl cyclase to form cAMP induces hyphal morphogenesis. The failure of cells lacking adenylyl cyclase (cyr1Δ) to form hyphae has suggested that cAMP s...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1111/mmi.13588
更新日期:2017-03-01 00:00:00
abstract::The interactions between pathogenic bacteria and the host need to be resolved at the molecular level in order to develop novel vaccines and drugs. We have previously identified strepadhesin, a novel glycoprotein-binding activity in Streptococcus pyogenes, which is regulated by Mga, a regulator of streptococcal virulen...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1046/j.1365-2958.2001.02269.x
更新日期:2001-01-01 00:00:00
abstract::The Escherichia coli DNA glycosylase Mug excises 3,N(4)-ethenocytosines (epsilon C) and uracils from DNA, but its biological function is obscure. This is because epsilon C is not found in E. coli DNA, and uracil-DNA glycosylase (Ung), a distinct enzyme, is much more efficient at removing uracils from DNA than Mug. We ...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1046/j.1365-2958.2001.02559.x
更新日期:2001-09-01 00:00:00
abstract::Previous studies have shown that in Saccharomyces cerevisiae the mitochondrial and cytoplasmic forms of alanyl-tRNA synthetase are encoded by a single nuclear gene, ALA1, through alternative use of in-frame successive ACG triplets and a downstream AUG triplet. Here we show that despite the obvious participation of the...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1111/j.1365-2958.2006.05083.x
更新日期:2006-04-01 00:00:00
abstract::Members of the bacterial genus Brucella are facultative intracellular pathogens that reside predominantly within membrane-bound compartments within two host cell types, macrophages and placental trophoblasts. Within macrophages, the brucellae route themselves to an intracellular compartment that is favourable for surv...
journal_title:Molecular microbiology
pub_type: 杂志文章,评审
doi:10.1111/j.1365-2958.2004.04017.x
更新日期:2004-05-01 00:00:00
abstract::The Gram-negative bacterium Vibrio cholerae is the infectious agent responsible for the disease Asiatic cholera. The genes required for V. cholerae virulence, such as those encoding the cholera toxin (CT) and toxin-coregulated pilus (TCP), are controlled by a cascade of transcriptional activators. Ultimately, the dire...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1111/j.1365-2958.2005.04589.x
更新日期:2005-05-01 00:00:00
abstract::Using the genomic SELEX, a total of six Escherichia coli DNA fragments have been identified, which formed complexes with transcription factor RutR. The RutR regulon was found to include a large number of genes encoding components for not only degradation of pyrimidines but also transport of glutamate, synthesis of glu...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1111/j.1365-2958.2007.05954.x
更新日期:2007-11-01 00:00:00
abstract::Micrococcus luteus secretes a small protein called Rpf, which has autocrine and paracrine signalling functions and is required for the resuscitation of dormant cells. Originally isolated from the supernatant of actively growing cultures, Rpf was also detected on the surface of actively growing bacteria. Most molecules...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1046/j.1365-2958.2002.03183.x
更新日期:2002-11-01 00:00:00
abstract::For malaria to be transmitted, the Plasmodium falciparum parasite must invade an erythrocyte and undergo gametocytogenesis. When mature intraerythrocytic gametocytes are taken up in a blood meal by a mosquito they emerge as gametes and, once fertilized, continue to differentiate into infectious sporozoites. One of the...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1046/j.1365-2958.2002.02986.x
更新日期:2002-06-01 00:00:00
abstract::Post-translational proteolysis-dependent regulation of critical cellular processes is a common feature in bacteria. The Escherichia coli Lon protease is involved in the control of the SOS response, acid tolerance and nutritional deprivation. Moreover, Lon plays a role in the regulation of toxin-antitoxin (TA) systems ...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1111/j.1365-2958.2011.07646.x
更新日期:2011-06-01 00:00:00
abstract::Expression of Escherichia coli hupA and hupB, the structural genes encoding the most abundant nucleoid-associated proteins HUalpha and HUbeta has been studied during cold shock. This article demonstrates that: (i) transcriptional expression of hupA is blocked following a sudden temperature downshift (from 37 degrees C...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1046/j.1365-2958.2002.02868.x
更新日期:2002-04-01 00:00:00
abstract::Arsenic is the most ubiquitous environmental toxin. Here, we demonstrate that bacteria have evolved the ability to use arsenic to gain a competitive advantage over other bacteria at least twice. Microbes generate toxic methylarsenite (MAs(III)) by methylation of arsenite (As(III)) or reduction of methylarsenate (MAs(V...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1111/mmi.14169
更新日期:2019-02-01 00:00:00
abstract::The stable RNA promoters of Escherichia coli are exquisitely sensitive to variations in the superhelical density of DNA. Previously, we have shown that binding of the DNA architectural protein FIS at the upstream activating sequences (UASs) of stable RNA promoters prevents the transcription complexes from inactivation...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1111/j.1365-2958.2004.04126.x
更新日期:2004-07-01 00:00:00
abstract::This study examined the role of P fimbriae in the establishment of bacteriuria. Patients (n = 17) were subjected to intravesical inoculation with an asymptomatic bacteriuria strain, Escherichia coli 83972, or its P-fimbriated (pap+/prs+) transformants. As shown by groupwise analysis, the pap+/prs+ transformants establ...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1046/j.1365-2958.2000.02165.x
更新日期:2000-11-01 00:00:00