Expression of
FLJB:Z66 on a Linear Plasmid of Salmonella Enterica Serovar Typhi is Dependent on FLIA and FLHDC and Regulated By OMPR.
Braz J Microbiol 2010;
41:729-40. [PMID:
24031550 PMCID:
PMC3768638 DOI:
10.1590/s1517-83822010000300025]
[Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2009] [Revised: 10/09/2009] [Accepted: 03/16/2010] [Indexed: 11/21/2022] Open
Abstract
Salmonella enterica serovar Typhi z66-positive strains have two different flagellin genes, fliC:d/j and fljB:z66, located on the chromosome and on a linear plasmid, respectively. To investigate the mechanism underlying the expressional regulation of fljB:z66, gene deletion mutants of the regulators FliA, FlhDC, and OmpR were constructed in this study. The expression levels of fliC and fljB:z66 were analyzed by qRT–PCR in the wild-type strain and mutants at high and low osmolarity. The results show that the expression levels of both fljB:z66 and fliC were greatly reduced in fliA and flhDC mutants under both high and low osmotic conditions. In the ompR mutant, the expression levels of fljB:z66, fliC, fliA, and flhD were increased at low osmotic conditions. SDS-PAGE and western blotting analysis of the secreted proteins revealed that the FljB:z66 was almost absent in the fliA and flhDC mutants at both high and low osmolarity. In the wild-type strain, the fljB:z66 was more highly expressed under high-osmolarity conditions than under low-osmolarity conditions. However, this difference in expression disappeared in the ompR mutant. Translational expression assay of FljB:z66 showed that the FljB:z66 expression was decreased in ompR mutant at both low and high osmolarity. These results suggest that the expression of fljB:z66 in S. enterica serovar Typhi is dependent on FliA and FlihDC, and OmpR can regulate the expression and secretion of FljB:z66 in different osmolarity.
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