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Laboratory of Molecular Biophysics
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Lawrie Skipper with Judith Armitage.
Methyl chemotaxis proteins (MCPs) are membrane receptors that bind attractants in R. sphaeroides resulting in the methylation of the MCP. This reaction results in the phosphorylation of CheA that then interacts with CheY, the protein that binds the flagella motor protein to promote flagella switching. It is thought that another protein, CheW, is required to bind both MCP and CheA for the CheA and MCP interaction to occur. The chemotaxis pathway is complicated by the fact there are a number of homologs for each type of protein. At present it is known there are 10 MCPs, 3 CheAs and 3 CheWs. But from preliminary genome sequencing that there may be as many as 5 CheAs and 4 CheWs. Our work this year has focussed on the role of the third CheW protein. We have determined that a single point mutation abolishes the ability of this protein to participate in transmission of a signal from the MCP to the flagella. This mutation involves a single Cys residue found only in this CheW and our current experiments aim to determine if it is involved in determining the higher order structure of the protein. Crystallisation trials using a Cys to Ser inactive mutant seem to provide a way forward to improve the crystals of CheW3 grown by us some time ago.
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