Identification of methylation sites in Rhodobacter chemoreceptors

Thesis

Chemotaxis in Rhodobacter sphaeroides occurs through the alteration of the level of rotational switching of its flagellum. The presence of attractants and repellents are sensed by methyl-accepting chemotaxis proteins (MCPs). The reversible methylation of certain glutamate residues in the methylation helices of MCPs is important in the adaptation aspect of chemotaxis. Previously established consensus methylation sites in other organisms were used for searches in the sequences of R. sphaeroides chemoreceptors for putative methylation sites. Site-directed mutagenesis was used to convert glutamine/glutamate residues to alanine in these putative sites on the cytoplasmic receptor TlpT and the transmembrane receptor McpH. Motility analyses of mutants showed that TlpT(Q475A) and TlpT(Q528A) cells have reduced motility. This indicates that these sites in TlpT could be important for methylation by CheR3 and demethylation by the CheBs.

Authors: Ozhan, A

• Publication date: 2010
• Type of award: MSc
• Level of award: Masters
• Awarding institution: University of Oxford
• Language: English
• Keywords: chemotaxis; Rhodobacter sphaeroides; methyl-accepting chemotaxis proteins
• Subjects: Biochemistry