MHYT, a new integral membrane sensor domain

MHYT. a new conserved protein domain with a likely signaling function. is d escribed. This domain consists of six transmembrane segments, three of whic h contain conserved methionine, histidine, and tyrosine residues that are p rojected to lie near the outer face of the cytoplasmic membrane. In Synecho cystis sp. PCC6803, this domain forms the N-terminus of the sensor histidin e kinase Slr2098. In Pseudomonas aeruginosa and several other organisms, th e MHYT domain forms the N-terminal part of a three-domain protein together with previously described GGDEF and EAL domains. both of which have been as sociated with signal transduction due to their presence in likely signaling proteins. In Bacillus subtilis YkoW protein. an additional PAS domain is f ound between the MHYT and GGDEF domains. A ykoW null mutant of B. subtilis did not exhibit any growth alterations, consistent with a non-essential, si gnaling role of this protein. A model of the membrane topology of the MHYT domain indicates that its conserved residues could coordinate one or two co pper ions. suggesting a role in sensing oxygen, CO, or NO. (C) 2001 Federat ion of European Microbiological Societies. Published by Elsevier Science B. V. All rights reserved.