title: Exonuclease activities associated with DNA polymerases alpha and beta of the archaebacterium Halobacterium halobium.
abstract: alpha-like and beta-like DNA polymerases have previously been isolated from a halophilic archaebacterium Halobacterium halobium. In this report, we show that the alpha-like DNA polymerase has an associated 3' to 5'-exonuclease activity which is specific for single-stranded DNA, sensitive to both aphidicolin and N-ethylmaleimide and dependent on high salt concentrations like the polymerase activity. As this DNA polymerase has been shown to contain a primase activity, it may be considered as the equivalent to both eukaryotic DNA polymerases alpha and delta. As shown by glycerol-gradient centrifugation and electrophoresis under denaturing conditions, the beta-like polymerase would appear to have a monomeric structure and comprise of a single 65-kDa polypeptide. This DNA polymerase has both 3' to 5'-exonuclease and 5' to 3'-exonuclease activities which, contrary to polymerase activity, are inhibited by high salt concentrations.
authors.affiliation: Institut Jacques Monod, Centre National de la Recherche Scientifique, Université Paris 7, France.
authors.forename: I
authors.initials: I
authors.lastname: Sorokine
authors.forename: K
authors.initials: K
authors.lastname: Ben-Mahrez
authors.forename: M
authors.initials: M
authors.lastname: Nakayama
authors.forename: M
authors.initials: M
authors.lastname: Kohiyama
mesh_terms: D004256:DNA Polymerase I / Q000032:analysis* / Q000737:chemistry; D004257:DNA Polymerase II / Q000032:analysis* / Q000737:chemistry; D005092:Exonucleases / Q000032:analysis*; D006217:Halobacterium / Q000201:enzymology*
chemical_list: D004256:DNA Polymerase I; D004257:DNA Polymerase II; D005092:Exonucleases