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Title: Functional analysis of PSPTO_1203 a FecI-like ECF Sigma Factor of Pseudomonas syringae pv. tomato DC3000

item Swingle, Bryan

Submitted to: Gordon Research Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 7/14/2010
Publication Date: 7/18/2010
Citation: Swingle, B.M. 2010. Functional analysis of PSPTO_1203 a FecI-like ECF Sigma Factor of Pseudomonas syringae pv. tomato DC3000. Gordon Research Conference Proceedings. 99/12.

Interpretive Summary:

Technical Abstract: We have been investigating how P. syringae responds to limited iron availability, a common stress in aerobic environments. We are mainly focused on the role of the extracytoplasmic function (ECF) sigma factors, which are one of the mechanisms used by bacteria to adjust gene regulation in response to the local environment. P. syringae encodes ten ECF sigma factors, five of which are members of the iron starvation (IS) subgroup of ECF sigma factors. We have used genome-wide screening methods to identify regions of the P. syringae genome that are enriched for each IS sigma factor. We became intrigued by the sigma encoded by PSPTO_1203 because it was apparently present at several locations. Secondary screening confirmed that it regulates the expression of two transcription units, which encode a TonB-transducer and an ABC type transporter respectively. We have mapped the 5’ end of PSPTO_1203 dependent transcripts initiated at these genes and used site directed mutagenesis to identify nucleotides in the promoter that affect transcription. Additionally, we have identified three siderophores that induce PSPTO_1203 dependent transcription and are testing whether the TonB-transducer and the anti sigma factor associated with PSPTO_1203 have a role in the induction pathway. A discussion of this sigma factor as a mechanism for cheating neighboring microbes will be presented.