期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1992
卷号：89
期号：18
页码：8666-8670
DOI：10.1073/pnas.89.18.8666
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Agrobacterium tumefaciens initiates the expression of pathogenic genes (vir genes) in response to host-derived phenolic signals through a two-component regulatory system consisting of VirA and VirG. alpha-Bromoacetosyringone (ASBr) was developed as an inhibitor of this induction process and found to be a specific and irreversible inhibitor of vir gene induction in this pathogen. Formal replacement of one of the methoxy groups of ASBr with iodine gave an equally effective inhibitor that could carry an 125I label. We report here that the resulting radiolabeled inhibitor does not react with the sensory component of this system, VirA, either in vivo or in vitro. Rather, two small proteins, p10 and p21, bind labeled inhibitor in vivo in a time period that is consistent with the exposure time required for the inhibition of vir gene expression. Labeling to these proteins was protected by preexposure to ASBr but not by alpha-bromo-3,5-dimethoxyacetophenone, a compound of comparable chemical reactivity but previously shown not to inhibit vir gene expression. Our findings suggest that proteins that are not tumor-inducing plasmid-encoded mediate vir gene activation in a step prior to the VirA/VirG two-component regulatory system.
