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Isolation and in vitro characterization of CheZ suppressors for the Escherichia coli chemotactic response regulator mutant CheYN23D

Sanna, M. Germana and Simon, Melvin I. (1996) Isolation and in vitro characterization of CheZ suppressors for the Escherichia coli chemotactic response regulator mutant CheYN23D. Journal of Biological Chemistry, 271 (13). pp. 7357-7361. ISSN 0021-9258.

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The phosphorylated form of the response regulator CheY promotes the tumble signal in Escherichia coli chemotaxis. Phospho-CheY is thought to interact with the switch at the base of the flagellar motor and cause reversal of flagellar rotation from counterclockwise to clockwise changing the swimming direction. Thus the level of phospho-CheY controls the direction of flagellar rotation. The decay of the tumble signal is caused by dephosphorylation of CheY. CheY has an intrinsic autophosphatase activity; however, this reaction is greatly accelerated by the presence of the CheZ protein. We have shown previously that mutations at residues Asn-23 and Lys-26 in CheY confer resistance to the dephosphorylation activity of CheZ (Sanna, M. G., Swanson, R. V., Bourret, R. B., and Simon, M. I.(1995) Mol. Microbiol. 15, 1069-1079). Here we show that mutant CheY(N23D) is impaired in binding to CheZ, which provides a possible explanation for its resistance to the dephosphorylation activity of CheZ. Moreover, we isolated CheZ second-site suppressors of CheY(N23D), which restore both dephosphorylation and binding activity in a CheY(N23D) background. When the CheZ suppressor mutations are mapped, they are found in two clusters at the N and C termini of the CheZ protein which could define two regions of interaction with CheY. Furthermore, these regions may generate a surface in the folded three-dimensional structure of CheZ required for interaction with CheY.

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Additional Information:©1996 by The American Society for Biochemistry and Molecular Biology, Inc. Received for publication, November 10, 1995, and in revised form, January 16, 1996. We thank Lisa Alex, Lorna Brundage, Ron Swanson, and Bob Bourret for critical reading of the manuscript and Steve Marsh, Rick Colayco, and Barbara Perry for DNA sequencing.
Issue or Number:13
Record Number:CaltechAUTHORS:SANjbc96
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:6025
Deposited By: Lindsay Cleary
Deposited On:14 Nov 2006
Last Modified:02 Oct 2019 23:28

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