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The putative Agrobacterium transcriptional activator‐like virulence protein VirD5 may target T‐complex to prevent the degradation of coat proteins in the plant cell nucleus
Author(s) -
Wang Yafei,
Peng Wei,
Zhou Xu,
Huang Fei,
Shao Lingyun,
Luo Meizhong
Publication year - 2014
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.12866
Subject(s) - biology , agrobacterium , bimolecular fluorescence complementation , arabidopsis , agrobacterium tumefaciens , effector , microbiology and biotechnology , electrophoretic mobility shift assay , f box protein , protein subunit , mutant , yeast , proteasome , biochemistry , transformation (genetics) , ubiquitin ligase , transcription factor , ubiquitin , gene
SummaryAgrobacterium exports at least five virulence proteins (VirE2, VirE3, VirF, VirD2, VirD5) into host cells and hijacks some host plant factors to facilitate its transformation process. Random DNA binding selection assays ( RDSA s), electrophoretic mobility shift assays ( EMSA s) and yeast one‐hybrid systems were used to identify protein‐bound DNA elements. Bimolecular fluorescence complementation, glutathione S‐transferase pull‐down and yeast two‐hybrid assays were used to detect protein interactions. Protoplast transformation, coprecipitation, competitive binding and cell‐free degradation assays were used to analyze the relationships among proteins. We found that Agrobacterium VirD5 exhibits transcriptional activation activity in yeast, is located in the plant cell nucleus, and forms homodimers. A specific VirD5‐bound DNA element designated D5 RE (VirD5 response element) was identified. VirD5 interacted directly with Arabidopsis VirE2 Interacting Protein 1 (At VIP 1). However, the ternary complex of VirD5–At VIP 1–VirE2 could be detected, whereas that of VirD5–At VIP 1– VBF (At VIP 1 Binding F‐box protein) could not. We demonstrated that VirD5 competes with VBF for binding to At VIP 1 and stabilizes At VIP 1 and VirE2 in the cell‐free degradation system. Our results indicated that VirD5 may act as both a transcriptional activator‐like effector to regulate host gene expression and a protector preventing the coat proteins of the T‐complex from being quickly degraded by the host's ubiquitin proteasome system ( UPS ).