Nature Structural Biology
6, 729 - 734 (1999)
doi:10.1038/11495
Solution structure of the homodimeric core domain of Escherichia coli histidine kinase EnvZChieri Tomomori1, Toshiyuki Tanaka1, Rinku Dutta2, Heiyoung Park2, Soumitra K. Saha2, Yan Zhu2, Rieko Ishima3, 4, Dingjiang Liu3, 5, Kit I. Tong3, Hirofumi Kurokawa3, Hong Qian3, Masayori Inouye2
& Mitsuhiko Ikura31
Center for Tsukuba Advanced Research Alliance and Institute of Applied Biochemistry, University of Tsukuba, Tsukuba, Ibaraki 305-8577, Japan. 2
Department of Biochemistry, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, New Jersey 08854, USA. 3
Division of Molecular and Structural Biology, Ontario Cancer Institute and Department of Medical Biophysics, University of Toronto, Toronto, Ontario M5G 2M9, Canada. 4
Present address: Molecular Structural Biology Unit, National Institute of Dental Research, National Institutes of Health, Bethesda, Maryland 20892, USA. 5
Present address: Schering-Plough Research Institute, Kenilworth, New Jersey 07033-0539, USA.
Correspondence should be addressed to Mitsuhiko Ikura mikura@oci.utoronto.ca or Masayori Inouye inouye@rwja.umdnj.edu
Escherichia coli osmosensor EnvZ is a protein histidine kinase that plays a central role in osmoregulation, a cellular adaptation process involving the His-Asp phosphorelay signal transduction system. Dimerization of the transmembrane protein is essential for its autophosphorylation and phosphorelay signal transduction functions. Here we present the NMR-derived structure of the homodimeric core domain (residues 223−289) of EnvZ that includes His 243, the site of autophosphorylation and phosphate transfer reactions. The structure comprises a four-helix bundle formed by two identical helix-turn-helix subunits, revealing the molecular assembly of two active sites within the dimeric kinase.
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