title: Eukaryotic RNases H1 act processively by interactions through the duplex RNA-binding domain.
abstract: Ribonucleases H have mostly been implicated in eliminating short RNA primers used for initiation of lagging strand DNA synthesis. Escherichia coli RNase HI cleaves these RNA-DNA hybrids in a distributive manner. We report here that eukaryotic RNases H1 have evolved to be processive enzymes by attaching a duplex RNA-binding domain to the RNase H region. Highly conserved amino acids of the duplex RNA-binding domain are required for processivity and nucleic acid binding, which leads to dimerization of the protein. The need for a processive enzyme underscores the importance in eukaryotic cells of processing long hybrids, most of which remain to be identified. However, long RNA-DNA hybrids formed during immunoglobulin class-switch recombination are potential targets for RNase H1 in the nucleus. In mitochondria, where RNase H1 is essential for DNA formation during embryogenesis, long hybrids may be involved in DNA replication.
authors.affiliation: Laboratory of Molecular Genetics, National Institute of Child Health and Human Development Bethesda, MD 20892, USA.
authors.forename: Sergei A
authors.initials: SA
authors.lastname: Gaidamakov
authors.forename: Inna I
authors.initials: II
authors.lastname: Gorshkova
authors.forename: Peter
authors.initials: P
authors.lastname: Schuck
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Steinbach
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Yamada
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Crouch
authors.forename: Susana M
authors.initials: SM
authors.lastname: Cerritelli
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D004247:DNA / Q000378:metabolism*; D019281:Dimerization; D024202:Electrophoretic Mobility Shift Assay; D004926:Escherichia coli / Q000201:enzymology; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D011061:Poly A / Q000378:metabolism; D011071:Poly T / Q000378:metabolism; D017434:Protein Structure, Tertiary; D012313:RNA / Q000378:metabolism*; D012330:RNA, Double-Stranded / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism*; D016914:Ribonuclease H / Q000737:chemistry* / Q000378:metabolism*; D016415:Sequence Alignment; D020349:Surface Plasmon Resonance
chemical_list: D012330:RNA, Double-Stranded; D016601:RNA-Binding Proteins; D011061:Poly A; D011071:Poly T; C008950:poly A-T; D012313:RNA; D004247:DNA; D016914:Ribonuclease H; C078856:ribonuclease HI