Mutations in the chemotactic response regulator, CheY, that confer resistance to the phosphatase activity of CheZ.
Mol Microbiol
; 15(6): 1069-79, 1995 Mar.
Article
em En
| MEDLINE
| ID: mdl-7623663
ABSTRACT
CheY, a small cytoplasmic response regulator, plays an essential role in the chemotaxis pathway. The concentration of phospho-CheY is thought to determine the swimming behaviour of the cell high levels of phospho-CheY cause bacteria to rotate their flagella clockwise and tumble, whereas low levels of the phosphorylated form of the protein allow counter-clockwise rotation of the flagella and smooth swimming. The phosphorylation state of CheY in vivo is determined by the activity of the phosphoryl donor CheA, and by the antagonistic effect of dephosphorylation of phospho-CheY. The dephosphorylation rate is controlled by the intrinsic autohydrolytic activity of phospho-CheY and by the CheZ protein, which accelerates dephosphorylation. We have analysed the effect of CheZ on the dephosphorylation rates of several mutant CheY proteins. Two point mutations were identified which were 50-fold and 5-fold less sensitive to the activity of CheZ than was the wild-type protein. Nonetheless, the phosphorylation and autodephosphorylation rates of these mutants. CheY23ND and CheY26KE, were observed to be identical to those of wild-type CheY in the absence of CheZ. These are the first examples of cheY mutations that reduce sensitivity to the phosphatase activity of CheZ without being altered in terms of their intrinsic phosphorylation and autodephosphorylation rates. Interestingly, the residues Asn-23 and Lys-26 are located on a face of CheY far from the phosphorylation site (Asp-57), distinct from the previously described site of interaction with the histidine kinase CheA, and partially overlapping with a region implicated in interaction with the flagellar switch.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Proteínas de Bactérias
/
Quimiotaxia
/
Mutação Puntual
/
Fosfoproteínas Fosfatases
/
Proteínas de Membrana
Idioma:
En
Revista:
Mol Microbiol
Assunto da revista:
BIOLOGIA MOLECULAR
/
MICROBIOLOGIA
Ano de publicação:
1995
Tipo de documento:
Article
País de afiliação:
Estados Unidos