Transcriptional and Post-transcriptional Regulatory Mechanisms Controlling Type III Secretion

2019 ◽  
pp. 11-33
Author(s):  
Marcel Volk ◽  
Ines Vollmer ◽  
Ann Kathrin Heroven ◽  
Petra Dersch
Keyword(s):  
Type Iii Secretion ◽  
Regulatory Mechanisms ◽  
Type Iii ◽  
Transcriptional Regulatory ◽  
Transcriptional Regulatory Mechanisms

scholarly journals The Flagellar Sigma Factor FliA (ς28) Regulates the Expression of Salmonella Genes Associated with the Centisome 63 Type III Secretion System

2000 ◽  
Vol 68 (5) ◽  
pp. 2735-2743 ◽  
Author(s):  
Katrin Eichelberg ◽  
Jorge E. Galán
Keyword(s):  
Type Iii Secretion ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Regulatory Proteins ◽  
Regulatory Mechanisms ◽  
Marginal Effect ◽  
Type Iii ◽  
Transcriptional Regulatory ◽  
Serovar Typhimurium ◽  
Type Iii Protein Secretion

ABSTRACT One of the essential features of all pathogenic strains ofSalmonella enterica is the ability to enter into nonphagocytic cells. This pathogenic property is mediated by theSalmonella pathogenicity island 1 (SPI-1)-encoded type III secretion system. Expression of components and substrates of this system is subject to complex regulatory mechanisms. These mechanisms include a number of specific and global transcriptional regulatory proteins. In this study we have compared in S. entericaserovars Typhimurium and Typhi the effect of mutations in flagellar genes on the phenotypes associated with the SPI-1 type III protein secretion system. We found that serovar Typhi strains carrying a null mutation in either of the flagellar regulatory genes flhDCor fliA were severely deficient in entry into cultured epithelial cells and macrophage cytotoxicity. This defect could not be reversed by applying a mild centrifugal force, suggesting that the effects of the mutations were not due to the absence of motility. In contrast, the same mutations had no significant effect on the ability of serovar Typhimurium to enter into cultured Henle-407 cells or to induce macrophage cell death. Consistent with these observations, we found that the mutations in the flagellar regulatory proteins significantly reduced the expression of components of the SPI-1-encoded type III system in serovar Typhi but had a marginal effect in serovar Typhimurium. Our results therefore indicate that there is an overlap between regulatory mechanisms that control flagellar and type III secretion gene expression inSalmonella serovar Typhi.

scholarly journals Altered Ca2+ Regulation of Yop Secretion in Yersinia enterocolitica after DNA Adenine Methyltransferase Overproduction Is Mediated by Clp-Dependent Degradation of LcrG

2006 ◽  
Vol 188 (20) ◽  
pp. 7072-7081 ◽  
Author(s):  
Stefan Fälker ◽  
M. Alexander Schmidt ◽  
Gerhard Heusipp
Keyword(s):  
Yersinia Enterocolitica ◽  
Type Iii Secretion ◽  
Effector Proteins ◽  
Regulatory Mechanisms ◽  
Posttranslational Regulation ◽  
Bacterial Cells ◽  
Human Pathogen ◽  
Type Iii ◽  
Coordinated Expression ◽  
Dna Adenine Methyltransferase

ABSTRACT DNA methylation by the DNA adenine methyltransferase (Dam) interferes with the coordinated expression of virulence functions in an increasing number of pathogens. While analyzing the effect of Dam on the virulence of the human pathogen Yersinia enterocolitica, we observed type III secretion of Yop effector proteins under nonpermissive conditions. Dam alters the Ca2+ regulation of Yop secretion but does not affect the temperature regulation of Yop/Ysc expression. The phenotype is different from that of classical “Ca2+-blind” mutants of Yersinia, as Dam-overproducing (DamOP) strains still translocate Yops polarly into eukaryotic cells. Although transcription of the lcrGV and yopN-tyeA operons is slightly upregulated, LcrG is absent from lysates of DamOP bacteria, while the amounts of YopN and TyeA are not changed. We present evidence that clpXP expression increases after Dam overproduction and that the ClpP protease then degrades LcrG, thereby releasing a block in type III secretion. This is the first example of posttranslational regulation of type III secretion by the Clp protease and adds a new flavor to the complex regulatory mechanisms underlying the controlled release of effector proteins from bacterial cells.

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