mraW, an essential gene at the dcw cluster of Escherichia coli codes for acytoplasmic protein with methyltransferase activity

Three new open reading frames, mraZ, mraW and mraR (also called ftsL), were revealed by DNA sequencing immediately upstream of gene pbpB in the dcw cl uster of Escherichia coli. We have found that mraW and mraZ are active gene s, coding for two proteins with relative molecular masses of 34 800 and 17 300, respectively. MraW is a cytoplasmic protein that under overproduction condition is also loosely bound to the membrane. Soluble MraW was purified up to 90% by a single high performance electrophoresis (HPEC) step from an extract of an overproducing strain. The protein exhibits a S-adenosyl-depen dent methyltransferase activity on membrane-located substrates. (C) 1999 So ciete francaise de biochimie et biologie moleculaire/Editions scientifiques et medicales Elsevier SAS.