Identification of the Escherichia coli cysM Gene Encoding O-Acetylserine Sulphydrylase B by Cloning with Mini-Mu-lac Containing a Plasmid Replicon

SUMMARY: A region located at around 52' on the Escherichia coli chromosome was cloned by use of mini-Mu-lac containing a plasmid replicon and recloned into pBR322. Enzyme assays on transformants carrying the cloned fragments indicated the presence in the latter of the cysA and cysM genes coding for sulphate permease and O-acetylserine sulphydrylase B, respectively.