title: DNA polymerase III of Gram-positive eubacteria is a zinc metalloprotein conserving an essential finger-like domain.
abstract: DNA polymerase III (pol III) of Gram-positive eubacteria is a catalytically bifunctional DNA polymerase:3'-5' exonuclease [Low, R. L., Rashbaum, S. A., and Cozzarelli, N. R. (1976) J. Biol.Chem. 251, 1311-1325]. The pol III protein conserves, between its exonuclease and dNTP binding sites, a 35-residue segment of primary structure with the potential to form a zinc finger-like structure [Berg, J. M. (1990) Ann. Rev. Biochem. 19, 405-421]. This paper describes results of experiments which probe the capacity of this segment to bind zinc and the role of this segment in enzyme function. The results of metal and mutational analysis of a model pol III derived from Bacillus subtilis indicate that (i) the Gram-positive pol III is a metalloprotein containing tightly bound zinc in a stoichiometry of 1, (ii) the zinc atom is bound within the 35-residue segment, likely in one of two probable finger-like structures, and (iii) the integrity of the zinc-bound structure is specifically critical to the formation and/or function of the enzyme's polymerase site.
authors.affiliation: Department of Pharmacology and Molecular Toxicology, University of Massachusetts Medical School, Worcester 01655-0126, USA.
authors.forename: M H
authors.initials: MH
authors.lastname: Barnes
authors.forename: C J
authors.initials: CJ
authors.lastname: Leo
authors.forename: N C
authors.initials: NC
authors.lastname: Brown
mesh_terms: D000595:Amino Acid Sequence; D001412:Bacillus subtilis / Q000201:enzymology; D001665:Binding Sites / Q000235:genetics; D002384:Catalysis; D017124:Conserved Sequence / Q000235:genetics; D003545:Cysteine / Q000235:genetics / Q000378:metabolism; D004258:DNA Polymerase III / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004583:Electrons; D006094:Gram-Positive Bacteria / Q000201:enzymology*; D006639:Histidine / Q000235:genetics / Q000378:metabolism; D007501:Iron / Q000378:metabolism; D008666:Metalloendopeptidases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008741:Methyl Methanesulfonate / Q000031:analogs & derivatives / Q000378:metabolism; D008969:Molecular Sequence Data; D017354:Point Mutation; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D016335:Zinc Fingers / Q000235:genetics; D015037:Zinc Radioisotopes / Q000378:metabolism
chemical_list: D011994:Recombinant Proteins; D015037:Zinc Radioisotopes; C014674:methyl methanethiosulfonate; D006639:Histidine; D008741:Methyl Methanesulfonate; D007501:Iron; D004258:DNA Polymerase III; D008666:Metalloendopeptidases; D003545:Cysteine