ABSTRACT
Objective To study the distribution and evolution of yiiG, a Salmonella gene encoding a candidate type secretedsubstrate .Methods Salmonella genomes were comprehensively screened for yiiG distribution with se-quence alignment strategies .The evolutionary history of yiiG was traced .Comparative genomic analysis was per-formed to study the evolutionary mechanisms of yiiG gene acquisition , loss and duplication .RNA-seq data were combined to analyzing the correlation between yiiG and other virulence factors .A variety of bioinformatic tools were used for discovering the possible type Ⅲsecretion signals .Results yiiG distributed in S.enterica subsp.enterica but variable in other subspecies of S.enterica.No yiiG was found in S.bongori.Besides Salmonella, only a part of Shigella and E.coli strains were detected with yiiG homologs .The genomic locus of yiiG and its adjacency showed conservation among all Salmonella, E.coli and Shigella strains.In most of the serovars of S.enterica subsp.enteri-ca, there was a head-to-head tandem whole yiiG repeat sequence upstream the yiiG gene, which was renamed as yiiGRrc.RNA-seq analysis showed that yiiG gene expression level was highly correlated with T 3SS-related genes . Bioinformatic prediction also indicated the T 3SS effector signals in YiiG N-terminus.Conclusions yiiG represented an ancient genomic locus , which will be a hot spot where rearrangement events frequently happened .The function of yiiG could potentially be related with Salmonella virulence.Finally, a new protein-encoding gene (yiiGRrc) was newly identified that was closely related with yiiG, providing the target for further understanding the composition , function and function variation of yiiG gene family .
ABSTRACT
Objective To explore the potential pathogenesis of Yersinia pestis and provide new clues for vaccine development through comparative proteomic analysis of wild-type and pCD1 cured strain of Yersinia pestis 201.Methods Differentially expressed proteins at 26℃ and 37℃ were separated and identified using two-dimensional electrophoresis coupled with mass spectrometry .Results A total of 24 differently expressed proteins were successfully identified from the samples of bacteria grown at 26℃ and 25 proteins at 37℃.Among these, 7 proteins were encoded by pCD 1 plasmid. Conclusion Through comparative proteomic research, we have found that the abundance of several proteins can be dramatically changed when the large plasmid pCD 1 is missing,suggesting that the plasmid can regulate the expression of many genes located in the chromosome .
ABSTRACT
Objective To investigate the effects of shiga toxin ( Stx ) phage on the expression of type Ⅲsecretion system (T3SS) in E.coli O157 ∶H7.Methods A standard E.coli O157 ∶H7 strain, EDL933 and a natural Stx phage defective mutant of EDL 933 strain, TUV93-0 were used for this study .The expression of T3SS proteins was compared between EDL 933 and TUV93-0 strains.The expression of five operons ( LEE1-LEE5 ) was evaluated by measuring the green fluorescent protein ( GFP ) in five different plasmids with LEE1-LEE5 promoters, respectively.Results The expression of T3SS proteins in TUV93-0 mutant were significantly increased than those in EDL 933 strain.Moreover, the expression of LEE1, LEE2 and LEE5 were also increased in TUV93-0 mutant.Conclusion The deletion of Stx phage might enhance T3SS expression through the regulation of LEE 1.
ABSTRACT
A systematic analysis of the typeⅢ secretion genes of Aeromonas hydrophila strain AH-1 by constructing ahyR and ahyI mutant revealed that they are under quorum-sensing control. This observation was supported by the down-regulation of the TTSS genes in the presence of lacZ-TTSS gene promoter and the corresponding advanced secretion of AexT in ahyI mutant.