Abstract:
:Lipopolysaccharides (LPS), particularly the O-antigen component, are one of many virulence determinants necessary for Shigella flexneri pathogenesis. O-antigen biosynthesis is determined mostly by genes located in the rfb region of the chromosome. The rfc/wzy gene encodes the O-antigen polymerase, an integral membrane protein, which polymerizes the O-antigen repeat units of the LPS. The wild-type rfc/wzy gene has no detectable ribosome-binding site (RBS) and four rare codons in the translation initiation region (TIR). Site-directed mutagenesis of the rare codons at positions 4, 9 and 23 to those corresponding to more abundant tRNAs and introduction of a RBS allowed detection of the rfc/wzy gene product via a T7 promoter/polymerase expression assay. Complementation studies using the rfc/wzy constructs allowed visualization of a novel LPS with unregulated O-antigen chain length distribution, and a modal chain length could be restored by supplying the gene for the O-antigen chain length regulator (Rol/Wzz) on a low-copy-number plasmid. This suggests that the O-antigen chain length distribution is determined by both Rfc/Wzy and Rol/Wzz proteins. The effect on translation of mutating the rare codons was determined using an Rfc::PhoA fusion protein as a reporter. Alkaline phosphatase enzyme assays showed an approximately twofold increase in expression when three of the rare codons were mutated. Analysis of the Rfc/Wzy amino acid sequence using TM-PREDICT indicated that Rfc/Wzy had 10-13 transmembrane segments. The computer prediction models were tested by genetically fusing C-terminal deletions of Rfc/Wzy to alkaline phosphatase and beta-galactosidase. Rfc::PhoA fusion proteins near the amino-terminal end were detected by Coomassie blue staining and Western blotting using anti-PhoA serum. The enzyme activities of cells with the rfc/wzy fusions and the location of the fusions in rfc/wzy indicated that Rfc/Wzy has 12 transmembrane segments with two large periplasmic domains, and that the amino- and carboxy-termini are located on the cytoplasmic face of the membrane.
journal_name
Mol Microbioljournal_title
Molecular microbiologyauthors
Daniels C,Vindurampulle C,Morona Rdoi
10.1046/j.1365-2958.1998.00884.xsubject
Has Abstractpub_date
1998-06-01 00:00:00pages
1211-22issue
6eissn
0950-382Xissn
1365-2958journal_volume
28pub_type
杂志文章abstract::Three u.v.-induced mutants of the purine-cytosine permease gene of Saccharomyces cerevisiae, with altered apparent Michaelis constant of transport (Kmapp), were cloned and sequenced. One of the mutants had extensive nucleotide replacement, whereas the other two had a single mutation. To evaluate the contribution of th...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1111/j.1365-2958.1992.tb01757.x
更新日期:1992-10-01 00:00:00
abstract::The recent emergence of indolent and rapidly fatal drug-resistant strains of Mycobacterium tuberculosis has renewed interest in defining the molecular mechanisms of drug resistance in the tubercle bacilli. In this report, we have examined the mechanism of resistance to streptomycin (Sm) in M. tuberculosis through the ...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1111/j.1365-2958.1993.tb00924.x
更新日期:1993-11-01 00:00:00
abstract::Enteropathogenic Escherichia coli (EPEC) elicit changes in host cell morphology and cause actin rearrangement, a phenotype that has commonly been referred to as attaching/effacing (AE) lesions. The ability of EPEC to induce AE lesions is dependent upon a type III protein secretion/translocation system that is encoded ...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1046/j.1365-2958.1999.01655.x
更新日期:1999-12-01 00:00:00
abstract::Haemophilus influenzae is a human-specific pathogen and a major source of morbidity worldwide. Infection with this organism begins with colonization of the nasopharynx, a process that probably depends on adherence to respiratory epithelium. The Hia autotransporter protein is the major adhesin ex-pressed by a subset of...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1046/j.1365-2958.2002.03189.x
更新日期:2002-11-01 00:00:00
abstract:SUMMARY:The conserved bacterial protein RloC, a distant homologue of the tRNA(Lys) anticodon nuclease (ACNase) PrrC, is shown here to act as a wobble nucleotide-excising and Zn(++)-responsive tRNase. The more familiar PrrC is silenced by a genetically linked type I DNA restriction-modification (R-M) enzyme, activated b...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1111/j.1365-2958.2008.06387.x
更新日期:2008-09-01 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::The stalk is a universal structure of the large ribosomal subunit involved in the function of translation factors. The bacterial stalk is highly stable but its stability is notably reduced in eukaryotes, favouring a translation regulatory activity of this ribosomal domain, which has not been reported in prokaryotes. T...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1111/j.1365-2958.2005.04816.x
更新日期:2005-10-01 00:00:00
abstract::Magnetotactic bacteria contain nanometre-sized, membrane-bound organelles, called magnetosomes, which are tasked with the biomineralization of small crystals of the iron oxide magnetite allowing the organism to use geomagnetic field lines for navigation. A key player in this process is the HtrA/DegP family protease Ma...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1111/j.1365-2958.2011.07631.x
更新日期:2011-05-01 00:00:00
abstract::Despite their high genomic synteny, the Leishmania major and Leishmania infantum species exhibit extensive differences in mRNA expression patterns throughout the parasite's development. Yet, the underlying mechanisms for this species-specific differential gene expression are largely unknown. Here we report that Short ...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1111/j.1365-2958.2010.07226.x
更新日期:2010-07-01 00:00:00
abstract::A 25 kbp DNA fragment from the chromosome of Rhodobacter capsulatus B10 carrying hydrogenase (hup) determinants was completely sequenced. Coding regions corresponding to 20 open reading frames were identified. The R. capsulatus hydrogenase-specific gene (hup and hyp) products bear significant structural identity to hy...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1111/j.1365-2958.1993.tb01199.x
更新日期:1993-04-01 00:00:00
abstract::We show that Yersinia pestis and pesticin-sensitive isolates of Y. pseudotuberculosis possess a common 34 kbp DNA region that has all the hallmarks of a pathogenicity island and is inserted into different asparaginyl tRNA genes at different chromosomal locations in each species. This pathogenicity island (YP-HPI) is m...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1046/j.1365-2958.1999.01172.x
更新日期:1999-01-01 00:00:00
abstract::The polA gene of Escherichia coli encodes DNA polymerase I that is involved in DNA replication and repair. Despite the wide knowledge about structure and function of DNA polymerase I, there is little insight into the regulatory mechanisms involved in polA expression. DnaA is the initiator protein for DNA replication i...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1046/j.1365-2958.1997.2961658.x
更新日期:1997-03-01 00:00:00
abstract::Pseudomonas aeruginosa chronically colonizing the lungs of cystic fibrosis (CF) patients undergoes fast evolution leading to clonal divergence. More than half of the genotypes of P. aeruginosa clone C isolates exclusively from CF lung infection exhibit large chromosomal inversions (LCIs). To analyse the impact of LCIs...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1046/j.1365-2958.2003.03261.x
更新日期:2003-01-01 00:00:00
abstract::The Leishmania major aquaglyceroporin, LmAQP1, is responsible for the transport of trivalent metalloids, arsenite and antimonite. We have earlier shown that downregulation of LmAQP1 provides resistance to trivalent antimony compounds whereas increased expression of LmAQP1 in drug-resistant parasites can reverse the re...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1111/j.1365-2958.2007.05845.x
更新日期:2007-08-01 00:00:00
abstract::Deprivation of FtsN, the last protein in the hierarchy of divisome assembly, causes the disassembly of other elements from the division ring, even extending to already assembled proto-ring proteins. Therefore the stability and function of the divisome to produce rings active in septation is not guaranteed until FtsN i...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1111/j.1365-2958.2010.07134.x
更新日期:2010-05-01 00:00:00
abstract::In vivo and in vitro analyses indicate that transcription of the argO gene coding for an arginine exporter is regulated by the global transcriptional regulator Lrp, an effect that went by unnoticed in previous genome-scale screenings of the Lrp regulatory network in Escherichia coli. Lrp activates the argO promoter fo...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1111/j.1365-2958.2009.06950.x
更新日期:2009-12-01 00:00:00
abstract::The region of the antibiotic resistance plasmid R100 that encodes the plasmid-specific transfer gene traM has two tandemly aligned promoters separated by 145 nucleotides. The principal transcripts are 705 and 562 nucleotides long. Minor transcripts are 1550 and 1700 nucleotides long. The 705-base transcript appears to...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1111/j.1365-2958.1989.tb00202.x
更新日期:1989-04-01 00:00:00
abstract::Klebsiella pullulanase is a lipoprotein synthesized as a precursor with a signal peptide, which is processed by lipoprotein signal peptidase. To clarify the role of lipid modification of pullulanase, we purified lipid-modified wild-type and the unmodified (mutant) pullulanases and compared their properties. The Km and...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1111/j.1365-2958.1992.tb01482.x
更新日期:1992-02-01 00:00:00
abstract::A model for the topology of the PhoE porin has been proposed according to which the polypeptide traverses the outer membrane sixteen times mostly as amphipathic beta-sheets, thereby exposing eight loops at the cell surface. Until now, no evidence has been obtained for the surface exposure of the third loop. Recently, ...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1111/j.1365-2958.1993.tb01104.x
更新日期:1993-01-01 00:00:00
abstract::Peptidoglycan (PG), the major component of the bacterial cell wall, is one large macromolecule. To allow for the different curvatures of PG at cell poles and division sites, there must be local differences in PG architecture and eventually also chemistry. Here we report such local differences in the Gram-positive rod-...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1111/mmi.13629
更新日期:2017-04-01 00:00:00
abstract::The majority of characterized bacterial dipeptide permeases (Dpp) are membrane-associated complexes of five proteins belonging to the ABC-transporter family. They have been found to be involved in the uptake of essential amino acids, haem production, chemotaxis and sporulation. A 5.8 kb genomic DNA fragment of the ser...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1046/j.1365-2958.1998.00898.x
更新日期:1998-06-01 00:00:00
abstract::In Escherichia coli the flagellar regulon consists of more than 60 genes organized in three hierarchically and temporally regulated transcriptional classes. The flagellar sigma factor FliA (sigma(28)) is responsible for class 3 expression and, in the early phase of flagellar assembly, is inhibited by its anti-sigma fa...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1111/j.1365-2958.2007.05770.x
更新日期:2007-07-01 00:00:00
abstract::Cyanobacteria respond to changes in light or nutrient availability by modifications in their photosynthetic light harvesting antenna. In unicellular cyanobacteria a small polypeptide (NblA) is required for phycobilisome degradation following environmental stresses. In the filamentous strain Tolypothrix sp. PCC 7601 th...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1046/j.1365-2958.2003.03768.x
更新日期:2003-11-01 00:00:00
abstract::Listeria monocytogenes grows in the cytosol of mammalian cells and spreads from cell to cell without exiting the intracellular milieu. During cell-cell spread, bacteria become transiently entrapped in double-membrane vacuoles. Escape from these vacuoles is mediated in part by a bacterial phospholipase C (PC-PLC), whos...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1046/j.1365-2958.2000.01708.x
更新日期:2000-01-01 00:00:00
abstract::The cloned Citrobacter freundii ampC beta-lactamase is inducible in the presence of its regulatory gene ampR in Escherichia coli (Lindberg et al., 1985). The basal level of expression and inducibility are affected by two E. coli proteins encoded by the closely linked ampD and ampE genes. Deletion of both genes led to ...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1111/j.1365-2958.1989.tb00259.x
更新日期:1989-08-01 00:00:00
abstract::The flexible pilus of Aeromonas hydrophila is a morphologically and biochemically unique organelle which binds eukaryotic cell surfaces and whose expression is induced by specific physiochemical conditions. fxp, the structural gene coding for the flexible pilus subunit, was localized on a 7.6kb plasmid of A. hydrophil...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1111/j.1365-2958.1992.tb01449.x
更新日期:1992-09-01 00:00:00
abstract::The threonine dehydratase IlvA is part of the isoleucine biosynthesis pathway in the Gram-positive model bacterium Bacillus subtilis. Consequently, deletion of ilvA causes isoleucine auxotrophy. It has been reported that ilvA pseudo-revertants having a derepressed hom-thrCB operon appear in the presence of threonine. ...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1111/mmi.13429
更新日期:2016-09-01 00:00:00
abstract::Meningococcal gdhA, encoding the NADP-specific l-glutamate dehydrogenase (NADP-GDH), is essential for systemic infection in an infant rat model. In this paper, a limited transcriptional analysis detected differences in gdhA expression among clinical isolates. In strains expressing high levels of gdhA mRNA, two promote...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1111/j.1365-2958.2003.03947.x
更新日期:2004-03-01 00:00:00
abstract::In the mouse model for systemic infection, natural a/alpha strains of C. albicans are more virulent and more competitive than their spontaneous MTL-homozygous offspring, which arise primarily by loss of one chromosome 5 homologue followed by duplication of the retained homologue (uniparental disomy). Deletion of eithe...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1111/j.1365-2958.2007.05759.x
更新日期:2007-06-01 00:00:00
abstract::The type III secretion system (TTSS) is a modular apparatus assembled by many pathogenic Gram-negative bacteria and is designed to translocate proteins through the bacterial cell wall into the eukaryotic host cell. The conserved components of the TTSS comprise stacks of rings spanning the inner and outer bacterial mem...
journal_title:Molecular microbiology
pub_type: 杂志文章
doi:10.1046/j.1365-2958.2003.03555.x
更新日期:2003-07-01 00:00:00