Signal transduction pathways regulating genetic exchange
EMSL Project ID
34904
Abstract
The alphaproteobacterium R. capsulatus is a model organism for studying photosynthesis, nitrogen fixation, and hydrogen production. R. capsulatus also produces a virus-like particle called the "gene transfer agent" (RcGTA) that acts as a vector of genetic exchange. RcGTA production is maximal in the stationary phase of growth, and this stationary phase effect is at least partly caused by phosphate limitation. RcGTA production also requires the response-regulator protein CtrA, which is a master regulator required for the proper expression of ~200 genes. This includes a number of other signal transduction proteins such as 10 proteins predicted to be involved in histidyl-aspartyl phosphorelay signaling, and 9 proteins with conserved bis-(3'-5')-cyclic dimeric guanosine monophosphate (c-di-GMP) signaling domains. Our preliminary data indicate that c-di-GMP stimulates RcGTA production, and hence genetic exchange. This novel role of c-di-GMP may have significant implications for our understanding of lateral gene flow in nature. We will use whole-cell quantitative proteomics and activity-based protein profiling to address questions about how nutrient limitation affects the R. capsulatus proteome, how this nutrient limitation information is transduced in the cell, and the role of c-di-GMP in these processes. The driving force of our interest is to understand the mechanisms by which R. capsulatus responds to its environment and activates production of RcGTA. However, these experiments will also provide data that will be used for broader comparative proteomics to determine how nutrient deprivation affects the overall proteome of R. capsulatus. The existing proteome database for R. capsulatus will be used as a reference in analysis of the proteomic dynamics, and these studies will be paired with parallel transcriptome characterizations and enzymatic assays. In summary, this research will study changes in a bacterial proteome resulting from nutrient deprivation, and how these changes relate to a complex regulatory network that controls a number of processes, including the production of RcGTA. The questions we will address about nutrient limitation fall under the EMSL Science Theme "Biological Interactions and Dynamics", and the expertise and resources at EMSL are crucial for addressing these questions.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2009-10-09
End Date
2012-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members
Related Publications
Mercer, R.G., S.J. Callister, M.S. Lipton, L. Pasa-Tolic, H. Strnad, V. Paces, J.T. Beatty, and A.S.
Lang. 2010. Loss of the response regulator CtrA causes pleiotropic effects on gene expression but does not affect growth phase regulation in Rhodobacter capsulatus. Journal of Bacteriology 192: 2701-2710
Peña-Castillo L., R.G. Mercer, A. Gurinovich, S.J. Callister, A.T. Wright, A.B. Westbye, J.T. Beatty, and A.S. Lang. 2014. Gene co-expression network analysis in Rhodobacter capsulatus and application to comparative expression analysis of Rhodobacter sphaeroides. BMC Genomics 15: 730