Abstract
The proteins encoded by three Agrobacterial genes, atu5117, atu4860, and atu4856, are highly homologous to each other in amino acid sequence. All three proteins can bind to VirD2 and are named VBP1, VBP2, and VBP3 (VirD2-binding protein), respectively. VBP is involved in T-DNA transfer by recruiting the T-complex from the cytosol to the polar transport apparatus T4SS (type IV secretion system) and is defined as the “T-complex recruiting protein.” However, it remains unknown how these three homologous genes co-exist in a relatively small prokaryotic genome. To understand whether these three homologous genes are expressed differentially under virulence induction conditions, we examined the effects of virulence induction conditions, including various pH values, temperatures and acetosyringone (AS, an effective virulence inducer to Agrobacterium tumefaciens) concentrations, on the expression of the three VBP-encoding genes. Our data showed that vbp1 (atu5117) and vbp3 (atu4856) maintained constant expression under the tested induction conditions, whereas the expression of vbp2 (atu4860) was affected by the conditions. Culture conditions favorable to the expression of vbp2 differed from the reported induction conditions for other virulence proteins. In particular, the pH value was a crucial factor for the expression of vbp2. In addition, the deletion of vbp1 affected the expression of vbp2. Taken together, these results suggest that the mechanisms regulating the expression of these three homologous genes are different from the virulence induction mechanism and that VBP homologs are presumably involved in other biological processes in addition to T-complex recruitment.
Highlights
Agrobacterium tumefaciens is a well-known phytopathogen that causes crown gall tumor disease in various dicotyledonous plants
The responses of three VirD2-binding protein (VBP)-encoding genes to pH, temperature, and AS concentration are very different from the responses of other reported virulence genes to these three virulence induction factors
Both vbp1 and vbp3 could be expressed ubiquitously, despite varying induction conditions, indicating that neither of these genes are affected by well-known virulence induction conditions
Summary
Agrobacterium tumefaciens is a well-known phytopathogen that causes crown gall tumor disease in various dicotyledonous plants. Agrobacterium uses the VirB/D4 T4SS to transfer the T-DNA in the form of a VirD2-T-DNA. Expression of Agrobacterium Homologous vbp Genes nucleoprotein complex (called T-complex; Guo et al, 2011; Pacurar et al, 2011; Chandran, 2013; Kado, 2014). All three VBP homologs were confirmed to be able to bind VirD2 and designated VBP1 (encoded by atu5117), VBP2 (encoded by atu4860), and VBP3 (encoded by atu4856; Guo et al, 2007a,b). Our further investigation showed that VBPs are able to recruit the T-complex from the cytosol to the polar VirB/D4 transport apparatus T4SS (Guo et al, 2007a). VBPs were defined as being T-complex recruiting proteins
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
