Gene for the RNA polymerase sigma subunit mapped in Salmonella typhimurium and Escherichia coli by cloning and deletion.

Abstract
The genes for the RNA polymerase .sigma. subunit (rpoD) and DNA primase (dnaG) of S. typhimurium were cloned into [phage] .lambda. vectors. Combined restriction, deletion and functional analysis of the cloned fragment allows precise mapping of the genes on the fragment, establishes the direction in which rpoD is transcribed, and reveals the existence of at least one new gene in the vicinity. A closely homologous, smaller fragment of E. coli DNA, also cloned into .lambda. contains rpoD and at least part of dnaG.