Structural and functional studies of the HAMP domain of EnvZ, an osmosensing transmembrane histidine kinase in Escherichia coli

30Citations
Citations of this article
59Readers
Mendeley users who have this article in their library.

This article is free to access.

Abstract

The HAMP domain plays an essential role in signal transduction not only in histidine kinase but also in a number of other signal-transducing receptor proteins. Here we expressed the EnvZ HAMP domain (Arg180-Thr 235) with the R218K mutation (termed LRK) or with L RK connected with domain A (Arg180-Arg289) (termed LARK) of EnvZ, an osmosensing transmembrane histidine kinase in Escherichia coli, by fusing it with protein S. The LRK and LA RK proteins were purified after removing protein S. The CD analysis of the isolated L protein revealed that it consists of a random structure or is unstructured. This suggests that the EnvZ HAMP domain by itself is unable to form a stable structure and that this structural fragility may be important for its role in signal transduction. Interestingly the substitution of Ala 193 in the EnvZ HAMP domain with valine or leucine in Tez1A1, a chimeric protein of Tar and EnvZ, caused a constitutive OmpC phenotype. The CD analysis of LARK(A193L) revealed that this mutated HAMP domain possesses considerable secondary structures and that the thermostability of this entire LARK(A193L) became substantially lower than that of LA RK or just domain A, indicating that the structure of the HAMP domain with the A193L mutation affects the stability of downstream domain A. This results in cooperative thermodenaturation of domain A with the mutated HAMP domain. These results are discussed in light of the recently solved NMR structure of the HAMP domain from a thermophilic bacterium (Hulko, M., Berndt, F., Gruber, M., Linder, J. U., Truffault, V., Schultz, A., Martin, J., Schultz, J. E., Lupas, A. N., and Coles, M. (2006) Cell 126, 929-940). © 2007 by The American Society for Biochemistry and Molecular Biology, Inc.

Cite

CITATION STYLE

APA

Kishii, R., Falzon, L., Yoshida, T., Kobayashi, H., & Inouye, M. (2007). Structural and functional studies of the HAMP domain of EnvZ, an osmosensing transmembrane histidine kinase in Escherichia coli. Journal of Biological Chemistry, 282(36), 26401–26408. https://doi.org/10.1074/jbc.M701342200

Register to see more suggestions

Mendeley helps you to discover research relevant for your work.

Already have an account?

Save time finding and organizing research with Mendeley

Sign up for free