title: The cloning and sequence of the gene encoding the omega subunit of Escherichia coli RNA polymerase.
abstract: Omega is a small protein found associated with Escherichia coli RNA polymerase. The role of omega, if any, in transcription is not known. We have cloned the omega-encoding gene (rpoZ) so that we can produce large amounts of omega by over-production and to introduce mutations in its gene. We determined the N-terminal amino acid (aa) sequence of omega by aa microsequencing. Using the sequence we synthesized an eight-fold ambiguous 14-mer oligodeoxynucleotide probe and screened an E. coli genomic library using the base composition independent method of hybridization reported by Wood et al. [Proc. Natl. Acad. Sci. USA 82 (1985) 1585-1588]. With this method we isolated a clone that contained part of rpoZ which we used as a probe to isolate the complete gene. The sequence of the region containing the rpoZ gene predicts a highly charged protein of 91 aa with an Mr of 10 105. In addition, upstream from the gene is a good promoter-like sequence. We have verified by S1 mapping that in vivo transcripts originate from this promoter and possibly from a second promoter farther upstream.
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D012321:DNA-Directed RNA Polymerases / Q000096:biosynthesis / Q000235:genetics* / Q000502:physiology; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D029968:Escherichia coli Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D011487:Protein Conformation
chemical_list: D029968:Escherichia coli Proteins; D012321:DNA-Directed RNA Polymerases; C571073:RpoZ protein, E coli