The Escherichia coli orthologue of the Salmonella ushB gene (ushB(c)) produces neither UDP-sugar hydrolase activity nor detectable protein but has anidentical sequence to that of Escherichia coli cdh

Salmonella ushB, which encodes a membrane-bound UDP-sugar hydrolase, has an Escherichia coli orthologue (UshB(c)) which does not detectably produce th is activity. In this report, we show that ushB(c) does not produce any dete ctable protein either, despite being transcribed normally. Remarkably, ushB (c) is shown to have 100% sequence identity with E coli cdh, previously cha racterised as encoding an active CDP-diglyceride hydrolase, an apparent con tradiction with implications regarding enzyme evolution. We suggest that a useful gene designation is cdh (ushB(c)) rather than either ushB(c) or cdh, alone. (C) 2001 Federation of European Microbiological Societies. Publishe d by Elsevier Science B.V. All rights reserved.