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The HrpW protein of Lonsdalea quercina N‐5‐1 has pectate lyase activity and is required for full bacterial virulence
Author(s) -
Yang Li,
Xu Bochao,
He Wei,
Zhang Liqun
Publication year - 2014
Publication title -
journal of basic microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.58
H-Index - 54
eISSN - 1521-4028
pISSN - 0233-111X
DOI - 10.1002/jobm.201300342
Subject(s) - pectate lyase , virulence , biology , microbiology and biotechnology , hypersensitive response , virulence factor , bark (sound) , lyase , pathogen , biochemistry , enzyme , gene , plant disease resistance , pectinase , ecology
Lonsdalea quercina N‐5‐1 is a bacterial pathogen that causes poplar bark cankers. It has been isolated from the branch of Populus × euramericana cv. “74/76” in Henan, China. Previous studies have revealed that the Type III secretion system (T3SS) acts as an essential pathogenic factor in L . quercina N‐5‐1. HrpW is a putative effector of T3SS in strain N‐5‐1, which has a typical harpin domain at the amino terminal and a pectate lyase (Pel) domain at its carboxyl terminal. Genetic evidence had shown that, compared to the wild‐type and the complementary strain, the hrpW mutation causes a small but significant reduction in virulence when inoculated on the poplar branches. The amino terminal domain of HrpW was found to trigger tobacco hypersensitive response, but the carboxyl terminal domain of HrpW was not. Unlike most HrpW homologs in other bacteria, the carboxyl terminal domain of HrpW of strain N‐5‐1 exhibited detectable pectate lyase activity. Site‐direction mutations (W104A, W171M) further demonstrated that two tryptophan residues were essential to its pectate lyase activity. The results of the present work suggest that HrpW in L . quercina N‐5‐1 possesses pectate lyase activity and acts as a nonessential but important pathogenic factor in poplar bark canker disease.