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Mol Microbiol

Title:		Identification of amino acid residues of the pheromone-binding domain of the transcription factor TraR that are required for positive control
Author(s):		Costa ED; Cho H; Winans SC;
Address:		"Department of Microbiology, Cornell University, Ithaca, NY 14853, USA"
Journal Title:		Mol Microbiol
Year:		2009
Volume:		20090706
Issue:		3
Page Number:		341 - 351
DOI:		10.1111/j.1365-2958.2009.06755.x
ISSN/ISBN:		1365-2958 (Electronic) 0950-382X (Print) 0950-382X (Linking)
Abstract:		"Genes required for replication and for conjugal transfer of the Agrobacterium tumefaciens Ti plasmid are regulated by the quorum sensing transcription factor TraR, whose N-terminal domain binds to the pheromone 3-oxo-octanoylhomoserine lactone (OOHL) and whose C-terminal domain binds to specific DNA sequences called tra boxes. Here, we constructed 117 mutants, altering 103 surface-exposed amino acid residues of the TraR N-terminal domain. Each mutant was tested for activation of the traI promoter, where TraR binds to a site centred 45 nucleotides upstream of the transcription start site, and of the traM promoter, where TraR binds a site centred 66 nucleotides upstream. Alteration of 18 residues blocked activity at the traI promoter. Of these, alteration at three positions impaired TraR abundance or DNA binding, leaving 15 residues that are specifically needed for positive control. Of these 15 residues, nine also blocked or reduced activity at the traM promoter, while six had no effect. Amino acid residues required for activation of both promoters probably contact the C-terminal domain of the RNA polymerase alpha subunit, while residues required only for traI promoter activation may contact another RNA polymerase component"
Keywords:		"Agrobacterium tumefaciens/*genetics/metabolism Bacterial Proteins/genetics/*metabolism Binding Sites DNA, Bacterial/genetics DNA-Binding Proteins/genetics/*metabolism DNA-Directed RNA Polymerases/metabolism Gene Expression Regulation, Bacterial Genetic Co;"
Notes:		"MedlineCosta, Esther D Cho, Hongbaek Winans, Stephen C eng R01 GM042893/GM/NIGMS NIH HHS/ R01 GM042893-20/GM/NIGMS NIH HHS/ GM42893/GM/NIGMS NIH HHS/ Research Support, N.I.H., Extramural Research Support, Non-U.S. Gov't England 2009/07/16 Mol Microbiol. 2009 Aug; 73(3):341-51. doi: 10.1111/j.1365-2958.2009.06755.x. Epub 2009 Jul 6"