Open AccessInterplay among P seudomonas syringae H rp R , H rp S and H rp V proteins for regulation of the type III secretion system
Author(s) -
Jovanovic Milija,
Lawton Edward,
Schumacher Jörg,
Buck Martin
Publication year - 2014
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/1574-6968.12476
Subject(s) - pseudomonas syringae , biology , sigma factor , type three secretion system , psychological repression , genetics , bacteria , gene , promoter , gene expression , mutant
Pseudomonas syringae pv. tomato DC 3000, a plant pathogenic gram‐negative bacterium, employs the type III secretion system (T3 SS ) to cause disease in tomato and Arabidopsis and to induce the hypersensitive response in nonhost plants. The expression of T3 SS is regulated by the HrpL extracytoplasmic sigma factor. Expression of HrpL is controlled by transcriptional activators HrpR and HrpS and negative regulator HrpV. In this study, we analysed the organization of Hrp RS and HrpV regulatory proteins and interplay between them. We identified one key residue I26 in HrpS required for repression by HrpV. Substitution of I26 in HrpS abolishes its interaction with HrpV and impairs interactions between HrpS and HrpR and the self‐association of HrpS. We show that HrpS self‐associates and can associate simultaneously with HrpR and HrpV. We now propose that HrpS has a central role in the assembly of the regulatory Hrp RSV complex. Deletion analysis of HrpR and HrpS proteins showed that C‐terminal parts of HrpR and HrpS confer determinants indispensable for their self‐assembly.