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|Title:||Biochemical and molecular characterization of chemotaxis genes in Bacillus subtilis|
|Doctoral Committee Chair(s):||Ordal, George W.|
|Department / Program:||Biochemistry|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
|Abstract:||The cheF gene, an essential gene for chemotaxis in B. subtilis was cloned, localized and characterized. This gene is contained in a 7.7 kb EcoR1 DNA fragment that was isolated from a $\lambda$ Charon 4A B. subtilis chromosomal DNA library. A 0.7 kb Pst 1 DNA fragment of this 7.7 kb EcoR1 fragment was subcloned into an expression vector, pSI-1 and shown to complement the cheF mutation both for chemotaxis and for methanol formation in response to the addition of attractants.
The cheF mutant is defective in the positive stimuli pathway (addition of attractants and removal of repellents) but normal in the negative stimuli pathway (removal of attractants and addition of attractants). Unlike wild type B. subtilis, the cheF mutant failed to transfer methyl groups from methyl-accepting chemotactic proteins to a carrier, molecule X on addition of attractants. The deduced function of CheF in chemotaxis appears to be interacting with methylesterase, the enzyme responsible for removal of methyl groups from methyl-accepting chemotactic proteins.
The transcription unit which the cheF is located within was characterized. This transcription unit maps near pyrD and spcB, and at least ten complementation groups were found to be cotranscribed in this transcription unit. The regulation of this transcription unit seems to be under the control of SigA, the primary $\sigma$ factor in B. subtilis at the transcriptional level. Inspection of the promoter DNA sequence of this transcription unit revealed a potential consensus sequence for SigA promoters. Tn917-derived chemotaxis mutants whose mutations map near hisA and metC were analyzed. The expression of genes from these two loci requires the presence of an alternate $\sigma$ factor, SigD.
|Rights Information:||Copyright 1990 Ying, Ching-Wen|
|Date Available in IDEALS:||2011-05-07|
|Identifier in Online Catalog:||AAI9026361|
This item appears in the following Collection(s)
Graduate Dissertations and Theses at Illinois
Graduate Theses and Dissertations at Illinois