Dataset Information

HosA, a member of the SlyA family, regulates motility in enteropathogenic Escherichia coli.

ABSTRACT: In enteropathogenic and enterohemorraghic Escherichia coli (EPEC and EHEC), two members of the SlyA family of transcriptional regulators have been identified as SlyA. Western blot analysis of the wild type and the corresponding hosA and slyA deletion mutants indicated that SlyA and HosA are distinct proteins whose expression is not interdependent. Of 27 different E. coli strains (EPEC, EHEC, enteroinvasive, enteroaggregative, uropathogenic, and commensal) examined, 14 were positive for both genes and proteins. To investigate hosA expression, a hosA::luxCDABE reporter gene fusion was constructed. hosA expression was significantly reduced in the hosA but not the slyA mutant and was influenced by temperature, salt, and pH. In contrast to SlyA, HosA did not activate the cryptic E. coli K-12 hemolysin ClyA. Mutation of hosA did not influence type III secretion, the regulation of the LEE1 and LEE4 operons, or the ability of E2348/69 to form attaching-and-effacing lesions on intestinal epithelial cells. HosA is, however, involved in the temperature-dependent positive control of motility on swim plates and regulates fliC expression and FliC protein levels. In electrophoretic mobility shift assays, purified HosA protein bound specifically to the fliC promoter, indicating that HosA directly modulates flagellin expression. While direct examination of flagellar structure and the motile behavior of individual hosA cells grown in broth culture at 30 degrees C did not reveal any obvious differences, hosA mutants, unlike the wild type, clumped together, forming nonmotile aggregates which could account for the markedly reduced motility of the hosA mutant on swim plates at 30 degrees C. We conclude that SlyA and HosA are independent transcriptional regulators that respond to different physicochemical cues to facilitate the environmental adaptation of E. coli.

SUBMITTER: Ferrandiz MJ

PROVIDER: S-EPMC1064922 | biostudies-literature | 2005 Mar

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

HosA, a member of the SlyA family, regulates motility in enteropathogenic Escherichia coli.

Ferrándiz Maria-José MJ Bishop Keith K Williams Paul P Withers Helen H

Infection and immunity 20050301 3

In enteropathogenic and enterohemorraghic Escherichia coli (EPEC and EHEC), two members of the SlyA family of transcriptional regulators have been identified as SlyA. Western blot analysis of the wild type and the corresponding hosA and slyA deletion mutants indicated that SlyA and HosA are distinct proteins whose expression is not interdependent. Of 27 different E. coli strains (EPEC, EHEC, enteroinvasive, enteroaggregative, uropathogenic, and commensal) examined, 14 were positive for both gene ...[more]

PMID: 15731069

Similar Datasets

Project description:UnlabelledTranslocation of effector proteins via a type III secretion system (T3SS) is a widespread infection strategy among Gram-negative bacterial pathogens. Each pathogen translocates a particular set of effectors that subvert cell signaling in a way that suits its particular infection cycle. However, as effector unbalance might lead to cytotoxicity, the pathogens must employ mechanisms that regulate the intracellular effector concentration. We present evidence that the effector EspZ controls T3SS effector translocation from enteropathogenic (EPEC) and enterohemorrhagic (EHEC) Escherichia coli. Consistently, an EPEC espZ mutant is highly cytotoxic. Following ectopic expression, we found that EspZ inhibited the formation of actin pedestals as it blocked the translocation of Tir, as well as other effectors, including Map and EspF. Moreover, during infection EspZ inhibited effector translocation following superinfection. Importantly, while EspZ of EHEC O157:H7 had a universal "translocation stop" activity, EspZ of EPEC inhibited effector translocation from typical EPEC strains but not from EHEC O157:H7 or its progenitor, atypical EPEC O55:H7. We found that the N and C termini of EspZ, which contains two transmembrane domains, face the cytosolic leaflet of the plasma membrane at the site of bacterial attachment, while the extracellular loop of EspZ is responsible for its strain-specific activity. These results show that EPEC and EHEC acquired a sophisticated mechanism to regulate the effector translocation.ImportanceEnteropathogenic Escherichia coli (EPEC) and enterohemorrhagic E. coli (EHEC) are important diarrheal pathogens responsible for significant morbidity and mortality in developing countries and the developed world, respectively. The virulence strategy of EPEC and EHEC revolves around a conserved type III secretion system (T3SS), which translocates bacterial proteins known as effectors directly into host cells. Previous studies have shown that when cells are infected in two waves with EPEC, the first wave inhibits effector translocation by the second wave in a T3SS-dependent manner, although the factor involved was not known. Importantly, we identified EspZ as the effector responsible for blocking protein translocation following a secondary EPEC infection. Interestingly, we found that while EspZ of EHEC can block protein translocation from both EPEC and EHEC strains, EPEC EspZ cannot block translocation from EHEC. These studies show that EPEC and EHEC employ a novel infection strategy to regulate T3SS translocation.

Project description:Enteropathogenic Escherichia coli (EPEC) infection triggers the release of ATP from host intestinal cells, and the ATP is broken down to ADP, AMP, and adenosine in the lumen of the intestine. Ecto-5'-nucleotidase (CD73) is the main enzyme responsible for the conversion of 5'-AMP to adenosine, which triggers fluid secretion from host intestinal cells and also has growth-promoting effects on EPEC bacteria. In a recent study, we examined the role of the host enzyme CD73 in EPEC infection by testing the effect of ecto-5'-nucleotidase inhibitors. Zinc was a less potent inhibitor of ecto-5'-nucleotidase in vitro than the nucleotide analog alpha,beta-methylene-ADP, but in vivo, zinc was much more efficacious in preventing EPEC-induced fluid secretion in rabbit ileal loops than alpha,beta-methylene-ADP. This discrepancy between the in vitro and in vivo potencies of the two inhibitors prompted us to search for potential targets of zinc other than ecto-5'-nucleotidase. Zinc, at concentrations that produced little or no inhibition of EPEC growth, caused a decrease in the expression of EPEC protein virulence factors, such as bundle-forming pilus (BFP), EPEC secreted protein A, and other EPEC secreted proteins, and reduced EPEC adherence to cells in tissue culture. The effects of zinc were not mimicked by other transition metals, such as manganese, iron, copper, or nickel, and the effects were not reversed by an excess of iron. Quantitative real-time PCR showed that zinc reduced the abundance of the RNAs encoded by the bfp gene, by the plasmid-encoded regulator (per) gene, by the locus for the enterocyte effacement (LEE)-encoded regulator (ler) gene, and by several of the esp genes. In vivo, zinc reduced EPEC-induced fluid secretion into ligated rabbit ileal loops, decreased the adherence of EPEC to rabbit ileum, and reduced histopathological damage such as villus blunting. Some of the beneficial effects of zinc on EPEC infection appear to be due to the action of the metal on EPEC bacteria as well as on the host.

Dataset Information

HosA, a member of the SlyA family, regulates motility in enteropathogenic Escherichia coli.

Publications

HosA, a member of the SlyA family, regulates motility in enteropathogenic Escherichia coli.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets