| Title: | The quorum-sensing protein TraR of Agrobacterium tumefaciens is susceptible to intrinsic and TraM-mediated proteolytic instability |
| Author(s): | Costa ED; Chai Y; Winans SC; |
| Address: | "Department of Microbiology, Cornell University, Ithaca, NY 14850, USA" |
| DOI: | 10.1111/j.1365-2958.2012.08037.x |
| ISSN/ISBN: | 1365-2958 (Electronic) 0950-382X (Print) 0950-382X (Linking) |
| Abstract: | "TraR of Agrobacterium tumefaciens is a LuxR-type transcription factor that regulates genes required for replication and conjugation of the tumour-inducing plasmid. TraR binds the pheromone 3-oxo-octanoylhomoserine lactone (OOHL) and requires this molecule for folding into a protease-resistant, soluble conformation. Even after binding to OOHL, TraR is degraded at readily detectable rates. Here we show that the N-terminal domain of TraR, which binds OOHL, is more resistant to degradation than the full length protein, suggesting that sites on the C-terminal DNA binding domain [TraR(170-234)] enhance protein turnover. A fusion between GFP and TraR(170-234) was poorly fluorescent, and truncations of this fusion protein allowed us to identify residues in this domain that contribute to protein degradation. TraR activity was previously shown to be inhibited by the antiactivator TraM. These proteins form 2:2 complexes that fail to bind DNA sequences. Here we show that TraM sharply decreased the accumulation of TraR in whole cells, indicating that TraM facilitates proteolysis of TraR. The TraM component of these complexes is spared from proteolysis, and could therefore act catalytically" |
| Keywords: | "Acyl-Butyrolactones/*metabolism Agrobacterium tumefaciens/genetics/*metabolism Bacterial Proteins/*metabolism *Gene Expression Regulation, Bacterial Protein Binding Protein Stability Proteolysis *Quorum Sensing;" |
| Notes: | "MedlineCosta, Esther D Chai, Yunrong Winans, Stephen C eng R01 GM042893/GM/NIGMS NIH HHS/ R01 GM042893-21/GM/NIGMS NIH HHS/ GM42893/GM/NIGMS NIH HHS/ Research Support, N.I.H., Extramural Research Support, Non-U.S. Gov't England 2012/04/21 Mol Microbiol. 2012 Jun; 84(5):807-15. doi: 10.1111/j.1365-2958.2012.08037.x. Epub 2012 Apr 19" |
