The Clostridium acetobutylicum ATCC 824 DNA containing the 3' end of a PriA homolog, deformylase (def, and the 5' and of formyltransferase (fmt) has been cloned, sequenced, and used to complement an Escherichia coli mutant. While def and fmt have been found sharing an operon in other organisms, the presence of a third gene within a putative operon has not previously been found.