title: Crystal structure of metagenome-derived LC9-RNase H1 with atypical DEDN active site motif.
abstract: The crystal structure of metagenome-derived LC9-RNase H1 was determined. The structure-based mutational analyses indicated that the active site motif of LC9-RNase H1 is altered from DEDD to DEDN. In this motif, the location of the second glutamate residue is moved from αA-helix to β1-strand immediately next to the first aspartate residue, as in the active site of RNase H2. However, the structure and enzymatic properties of LC9-RNase H1 highly resemble those of RNase H1, instead of RNase H2. We propose that LC9-RNase H1 represents bacterial RNases H1 with an atypical DEDN active site motif, which are evolutionarily distinct from those with a typical DEDD active site motif.
authors.affiliation: Department of Material and Life Science, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Tri-Nhan
authors.initials: TN
authors.lastname: Nguyen
authors.forename: Dong-Ju
authors.initials: DJ
authors.lastname: You
authors.forename: Eiko
authors.initials: E
authors.lastname: Kanaya
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Koga
authors.forename: Shigenori
authors.initials: S
authors.lastname: Kanaya
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D004252:DNA Mutational Analysis; D019143:Evolution, Molecular; D006801:Humans; D054892:Metagenome / Q000235:genetics*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016914:Ribonuclease H / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
chemical_list: D016914:Ribonuclease H; C078856:ribonuclease HI