Agrobacterium tumefaciens, a gram negative soil bacterium that can live in parasitic association with higher plants, will be used to understand how disease-causing microbes and their hosts interact, and may also provide fundamental insights about how cells and organisms gain and process information from their surroundings. Agrobacterium senses wounded plants susceptible to infection by perceiving a class of phenolic compounds, while it senses tumorous plant tissues that are a consequence of infection by perceiving a class of derivatized amino acids and sugars known as opines. Two proteins (VirA and VirG) are required for the first of these recognition systems, and we will test the hypotheses that one of these is an environmental sensor, while the other is a transcriptional activator. We will determine whether the putative environmental sensor has a binding site for inducers, and whether it (like several homologous proteins) is capable of autophosphorylation. We will also obtain point mutants in each of these proteins that are constitutively active. To facilitate all these studies, we will attempt to reconstruct this regulatory system in E. coli. We will also study a separate regulatory system which regulates the virG promoter, identifying both cis- and trans-acting elements. Another set of T-plasmid encoded genes is inducible by opines, and little is known about the proteins mediating this response. We will identify trans-acting factors required to regulate opine-inducible genes, and subclone and sequence them. Finally and most importantly we will identify and characterize new loci which are induced by opines. By analyzing their predicted amino acid sequence and by characterizing stains with mutations in each of these genes we will gain insights about their role in the maintenance of this parasitic association.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
First Independent Research Support & Transition (FIRST) Awards (R29)
Project #
5R29GM042893-04
Application #
3467820
Study Section
Microbial Physiology and Genetics Subcommittee 2 (MBC)
Project Start
1989-07-01
Project End
1994-06-30
Budget Start
1992-07-01
Budget End
1993-06-30
Support Year
4
Fiscal Year
1992
Total Cost
Indirect Cost
Name
Cornell University
Department
Type
Schools of Earth Sciences/Natur
DUNS #
City
Ithaca
State
NY
Country
United States
Zip Code
14850
Pinto, Uelinton M; Pappas, Katherine M; Winans, Stephen C (2012) The ABCs of plasmid replication and segregation. Nat Rev Microbiol 10:755-65
Flores-Mireles, Ana Lidia; Eberhard, Anatol; Winans, Stephen C (2012) Agrobacterium tumefaciens can obtain sulphur from an opine that is synthesized by octopine synthase using S-methylmethionine as a substrate. Mol Microbiol 84:845-56
Costa, Esther D; Chai, Yunrong; Winans, Stephen C (2012) The quorum-sensing protein TraR of Agrobacterium tumefaciens is susceptible to intrinsic and TraM-mediated proteolytic instability. Mol Microbiol 84:807-15
Winans, Stephen C (2011) A new family of quorum sensing pheromones synthesized using S-adenosylmethionine and Acyl-CoAs. Mol Microbiol 79:1403-6
Wei, Yuping; Ryan, Gina T; Flores-Mireles, Ana L et al. (2011) Saturation mutagenesis of a CepR binding site as a means to identify new quorum-regulated promoters in Burkholderia cenocepacia. Mol Microbiol 79:616-32
Pinto, Uelinton M; Flores-Mireles, Ana L; Costa, Esther D et al. (2011) RepC protein of the octopine-type Ti plasmid binds to the probable origin of replication within repC and functions only in cis. Mol Microbiol 81:1593-606
Chai, Yunrong; Winans, Stephen C (2009) The chaperone GroESL enhances the accumulation of soluble, active TraR protein, a quorum-sensing transcription factor from Agrobacterium tumefaciens. J Bacteriol 191:3706-11
Costa, Esther D; Cho, Hongbaek; Winans, Stephen C (2009) Identification of amino acid residues of the pheromone-binding domain of the transcription factor TraR that are required for positive control. Mol Microbiol 73:341-51
Cho, Hongbaek; Pinto, Uelinton M; Winans, Stephen C (2009) Transsexuality in the rhizosphere: quorum sensing reversibly converts Agrobacterium tumefaciens from phenotypically female to male. J Bacteriol 191:3375-83