Characterization of the rho genes of Neisseria gonorrhoeae and Salmonella typhimurium

Miloso, Mariarosaria; Limauro, Danila; Alifano, Pietro; Rivellini, F.; Lavitola, Alfredo; Gulletta, Elio; Bruni, Carmelo B.

doi:10.1128/jb.175.24.8030-8037.1993

Cited by 19 publications

(14 citation statements)

References 44 publications

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“…Levels of lipA-and siaD-specific transcripts were normalized to 16S rRNA levels. Normalization with 16S rRNA or rho mRNA, coding for a transcription termination factor subjected to autoregulation in gramnegative bacteria (15,21), gave very similar results (data not shown). These results demonstrated a three-to fourfold increase in the amounts of siaD-or lipA-specific transcripts in intracellular bacteria compared to control bacteria, indicating that the meningococci up-regulate the genetic loci for capsular polysaccharide biosynthesis, translocation, and surface expression during their permanence in the eukaryotic host cell.…”

Section: Vol 75 2007 Meningococcal Capsule and Intracellular Survivsupporting

confidence: 65%

TheNeisseria meningitidisCapsule Is Important for Intracellular Survival in Human Cells

et al. 2007

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While much data exist in the literature about how Neisseria meningitidis adheres to and invades human cells, its behavior inside the host cell is largely unknown. One of the essential meningococcal attributes for pathogenesis is the polysaccharide capsule, which has been shown to be important for bacterial survival in extracellular fluids. To investigate the role of the meningococcal capsule in intracellular survival, we used B1940, a serogroup B strain, and its isogenic derivatives, which lack either the capsule or both the capsule and the lipooligosaccharide outer core, to infect human phagocytic and nonphagocytic cells and monitor invasion and intracellular growth. Our data indicate that the capsule, which negatively affects bacterial adhesion and, consequently, entry, is, in contrast, fundamental for the intracellular survival of this microorganism. The results of in vitro assays suggest that an increased resistance to cationic antimicrobial peptides (CAMPs), important components of the host innate defense system against microbial infections, is a possible mechanism by which the capsule protects the meningococci in the intracellular environment. Indeed, unencapsulated bacteria were more susceptible than encapsulated bacteria to defensins, cathelicidins, protegrins, and polymyxin B, which has long been used as a model compound to define the mechanism of action of CAMPs. We also demonstrate that both the capsular genes (siaD and lipA) and those encoding an efflux pump involved in resistance to CAMPs (mtrCDE) were up-regulated during the intracellular phase of the infectious cycle.

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Section: Vol 75 2007 Meningococcal Capsule and Intracellular Survivsupporting

confidence: 65%

TheNeisseria meningitidisCapsule Is Important for Intracellular Survival in Human Cells

et al. 2007

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“…The amino acid sequences of the nine Rho homologs were initially aligned using the program PILEUP. These nine homologs include the five determined in this work, plus the sequences deduced from the rho genes from E. coli (34) and Neisseria gonorrhoeae (27) and the homolog genes from B. subtilis (38) and Borrelia burgdorferi (47). This program uses the modification of the progressive alignment method described by Feng and Doolittle (14).…”

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confidence: 99%

Phylogenetic analysis of sequences from diverse bacteria with homology to the Escherichia coli rho gene

Opperman

Richardson

1994

J Bacteriol

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Genes from Pseudomonas fluorescens, Chromatium vinosum, Micrococcus luteus, Deinococcus radiodurans, and Thermotoga maritima with homology to the Escherichia coli rho gene were cloned and sequenced, and their sequences were compared with other available sequences. The species for all of the compared sequences are members of five bacterial phyla, including Thermotogales, the most deeply diverged phylum. This suggests that a rho-like gene is ubiquitous in the Bacteria and was present in their common ancestor. The comparative analysis revealed that the Rho homologs are highly conserved, exhibiting a minimum identity of 50% of their amino acid residues in pairwise comparisons. The ATP-binding domain had a particularly high degree of conservation, consisting of some blocks with sequences of residues that are very similar to segments of the a and , subunits of Fl-ATPase and of other blocks with sequences that are unique to Rho. The RNA-binding domain is more diverged than the ATP-binding domain. However, one of its most highly conserved segments includes a RNP1-like sequence, which is known to be involved in RNA binding. Overall, the degree of similarity is lowest in the first 50 residues (the first half of the RNA-binding domain), in the putative connector region between the RNA-binding and the ATP-binding domains, and in the last 50 residues of the polypeptide. Since functionally defective mutants for E. coli Rho exist in all three of these segments, they represent important parts of Rho that have undergone adaptive evolution. More recently, a gene with a sequence similar to that of E. coli rho was identified for B. subtilis (38). This suggested that the rho gene may not be confined to close relatives of E. coli.To help resolve the question of the universality of Rho homologs, we undertook the identification, isolation, and sequence characterization of genes with homology to the E. coli rho gene from evolutionarily diverged bacteria. Since mutations occur naturally and will accumulate over a long period of time, the sequences of diverged homolog genes can be used to determine the parts of Rho in which the residues are constrained to maintain the structure and function of the protein and the parts in which the residues are able to diverge. Thus, the finding of diverged homolog genes would also contribute to an understanding of the structural organization of Rho protein.We report here the sequences of rho gene homologs from five bacteria, two from the same subphylum as E. coli, and three from highly diverged phyla. These sequences along with recently reported sequences of rho gene homologs from three other diverged organisms and along with that of the E. coli rho gene are analyzed with respect to evolutionary relatedness and to the positions of conserved and diverged residues. The results indicate that a gene with homology to E. coli rho is widespread in the Bacteria, that it probably existed when the Bacteria diverged from the progenitor that also gave rise to the Archaea and the Eukarya, and that it encodes a protei...

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“…In that case, the putative R. sphaeroides Rho is similar in length and structure to the Rho factors from members of Proteobacteria (ϳ62 to 68% identity). It is at least ϳ50% identical to any other Rho factor whose structure has been reported (26,31,36,42).…”

Section: Resultsmentioning

confidence: 69%

“…The hexamer binds to the nascent RNA and by using the energy of ATP hydrolysis dissociates RNA from the transcription complex at certain sites. Rho possesses an RNA-binding, RNA-dependent ATPase and RNA-DNA helicase activities.Recently, homologs of E. coli rho were cloned from several diverse bacterial species (26,31,36,42); however, none of these were from members of the ␣ subdivision of class Proteobacteria. Sequencing of these rho genes revealed the structural similarities of their derived gene products to E. coli Rho, but very few functional studies have been undertaken with the E. coli Rho homologs.…”

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confidence: 99%

The Rhodobacter sphaeroides 2.4.1 rho gene: expression and genetic analysis of structure and function

Gomelsky¹,

Kaplan²

1996

J Bacteriol

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The gene which encodes transcription termination factor Rho from Rhodobacter sphaeroides 2.4.1, the gram-negative facultative photosynthetic bacterium, has been cloned and sequenced. The deduced protein shows a high level of sequence similarity to other bacterial Rho factors, especially those from proteobacteria. However, several amino acid substitutions in the conserved ATP-binding site have been identified. When expressed in Escherichia coli, the R. sphaeroides rho gene relieves Rho-dependent polarity of the trp operon, indicating interference with the transcription termination machinery of E. coli. A truncated version of R. sphaeroides Rho (Rho) is toxic to a bacterium related to R. sphaeroides, Paracoccus denitrificans, and is lethal to R. sphaeroides. We suggest that toxicity is due to the ability of Rho to form inactive heteromers with the chromosomally encoded intact Rho. We localized a minimal amino acid sequence within Rho which appears to be critical for its toxic effect and which we believe may be involved in protein-protein interactions. This region was previously reported to be highly conserved and unique among various Rho proteins. The lethality of rho in R. sphaeroides together with our inability to obtain a null mutation in rho suggests that Rho-dependent transcription termination is essential in R. sphaeroides. This is analogous to what is observed for gram-negative E. coli and contrasts with what is observed for gram-positive Bacillus subtilis. The genetic region surrounding the R. sphaeroides rho gene has been determined and found to be different compared with those of other bacterial species. rho is preceded by orf1, which encodes a putative integral membrane protein possibly involved in cytochrome formation or functioning. The gene downstream of rho is homologous to thdF, whose product is involved in thiophene and furan oxidation.Rhodobacter sphaeroides 2.4.1 is a facultative photosynthetic (PS) bacterium belonging to the ␣ subdivision of class Proteobacteria. To identify the transcriptional regulators of PS gene expression, we developed a genetic screen in a closely related but non-PS organism, Paracoccus denitrificans, which is capable of expressing R. sphaeroides genetic information (18, 32). We reasoned that activators and repressors of puf operon (23) expression, encoded by cosmids from an R. sphaeroides 2.4.1 genomic library, would increase and decrease, respectively, puf::lacZ expression in P. denitrificans. In an application of the above-described screen, we were able to identify cosmids carrying known activators of puf transcription (14, 15), as well as an uncharacterized cosmid, pUI8074. Unexpectedly, we found that the effect of pUI8074 was due to the presence of a truncated form of the R. sphaeroides rho gene.The bacterial rho gene encodes a factor responsible for protein-dependent transcription termination (reviewed in references 35 and 37). Most studies of the Rho factor have been performed on this factor from Escherichia coli (39). E. coli Rho is a hexameric protein composed of...

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Characterization of the rho genes of Neisseria gonorrhoeae and Salmonella typhimurium

Cited by 19 publications

References 44 publications

TheNeisseria meningitidisCapsule Is Important for Intracellular Survival in Human Cells

TheNeisseria meningitidisCapsule Is Important for Intracellular Survival in Human Cells

Phylogenetic analysis of sequences from diverse bacteria with homology to the Escherichia coli rho gene

The Rhodobacter sphaeroides 2.4.1 rho gene: expression and genetic analysis of structure and function

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