Direct and Indirect Targeting of PP2A by Conserved Bacterial Type-III Effector Proteins

PLoS Pathogens

David L. Coplin¹  Charles Boone¹  Jong Hyun Ham²  Lin Jin²  Jaricelis Soto-Hernández²  Seung-Mann Paek²  Sang Yeol Lee²  David Mackey³  Wanying Zhao⁴  Rosemary Hage⁵  Min Gab Kim⁶ 

[1] College of Pharmacy, Research Institute of Pharmaceutical Science, PMBBRC, Gyeongsang National University, Jinju daero, Jinju, Republic of Korea;Department of Horticulture and Crop Science, The Ohio State University, Columbus, Ohio, United States of America;Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada;Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center, Baton Rouge, Louisiana, United States of America;Department of Plant Pathology, The Ohio State University, Columbus, Ohio, United States of America;Division of Applied Life Science (BK21Plus), PMBBRC, Gyeongsang National University, Jinju daero, Jinju, Republic of Korea

关键词: Arabidopsis thaliana;    Maize;    Leaves;    Plant bacterial pathogens;    Cell death;    Yeast;    Membrane proteins;    Seedlings;   

DOI  :  10.1371/journal.ppat.1005609

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

Bacterial AvrE-family Type-III effector proteins (T3Es) contribute significantly to the virulence of plant-pathogenic species of Pseudomonas, Pantoea, Ralstonia, Erwinia, Dickeya and Pectobacterium, with hosts ranging from monocots to dicots. However, the mode of action of AvrE-family T3Es remains enigmatic, due in large part to their toxicity when expressed in plant or yeast cells. To search for targets of WtsE, an AvrE-family T3E from the maize pathogen Pantoea stewartii subsp. stewartii, we employed a yeast-two-hybrid screen with non-lethal fragments of WtsE and a synthetic genetic array with full-length WtsE. Together these screens indicate that WtsE targets maize protein phosphatase 2A (PP2A) heterotrimeric enzyme complexes via direct interaction with B’ regulatory subunits. AvrE1, another AvrE-family T3E from Pseudomonas syringae pv. tomato strain DC3000 (Pto DC3000), associates with specific PP2A B’ subunit proteins from its susceptible host Arabidopsis that are homologous to the maize B’ subunits shown to interact with WtsE. Additionally, AvrE1 was observed to associate with the WtsE-interacting maize proteins, indicating that PP2A B’ subunits are likely conserved targets of AvrE-family T3Es. Notably, the ability of AvrE1 to promote bacterial growth and/or suppress callose deposition was compromised in Arabidopsis plants with mutations of PP2A genes. Also, chemical inhibition of PP2A activity blocked the virulence activity of both WtsE and AvrE1 in planta. The function of HopM1, a Pto DC3000 T3E that is functionally redundant to AvrE1, was also impaired in specific PP2A mutant lines, although no direct interaction with B’ subunits was observed. These results indicate that sub-component specific PP2A complexes are targeted by bacterial T3Es, including direct targeting by members of the widely conserved AvrE-family.

【 授权许可】

CC BY