title: Structure and function of lineage-specific sequence insertions in the bacterial RNA polymerase beta' subunit.
abstract: The large beta and beta' subunits of the bacterial core RNA polymerase (RNAP) are highly conserved throughout evolution. Nevertheless, large sequence insertions in beta and beta' characterize specific evolutionary lineages of bacteria. The Thermus aquaticus RNAP beta' subunit contains a 283 residue insert between conserved regions A and B that is found in only four bacterial species. The Escherichia coli RNAP beta' subunit contains a 188 residue insert in the middle of conserved region G that is found in a wide range of bacterial species. Here, we present structural studies of these two beta' insertions. We show that the inserts comprise repeats of a previously characterized fold, the sandwich-barrel hybrid motif (as predicted from previous sequence analysis) and that the inserts serve significant roles in facilitating protein/protein and/or protein/nucleic acid interactions.
authors.affiliation: The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA.
authors.forename: Mark
authors.initials: M
authors.lastname: Chlenov
authors.forename: Shoko
authors.initials: S
authors.lastname: Masuda
authors.forename: Katsuhiko S
authors.initials: KS
authors.lastname: Murakami
authors.forename: Vadim
authors.initials: V
authors.lastname: Nikiforov
authors.forename: Seth A
authors.initials: SA
authors.lastname: Darst
authors.forename: Arkady
authors.initials: A
authors.lastname: Mustaev
mesh_terms: D000595:Amino Acid Sequence; D018360:Crystallography, X-Ray; D012321:DNA-Directed RNA Polymerases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D020035:Holoenzymes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid
chemical_list: D020035:Holoenzymes; D012321:DNA-Directed RNA Polymerases; C105078:RNA polymerase beta subunit