title: Primary structure and properties of ribonuclease Bm2 (RNase Bm2) from Bryopsis maxima.
abstract: A base non-specific ribonuclease (RNase Bm2) was isolated from a green algae (Ulvophyceae, Bryopsis maxima) as a single band on SDS-PAGE, and its primary structure and enzymatic properties, including base specificity, were investigated. The amino acid sequence of RNase Bm2 was homologous to many RNase T2 family RNases, and their characteristic CAS sequences were also conserved. The molecular mass of RNase Bm2 was 24444 Da, and its optimal pH was 5.5. RNase Bm2 was a poly U preferential RNase, similar to RNase MC1 from bitter gourd. The base specificity of this RNase suggested that the base specificity of the B1- and B2-base binding sites of RNase Bm2 were G > or = U > C >> A and U > G > C >> A, respectively. The estimated active site of RNase Bm2 was very similar to that of RNase MC1 from bitter gourds; however, a tyrosine residue at the B1-base binding site that is conserved for all RNase T2 family RNases was replaced by a tryptophan residue. Here we discuss the effect of this replacement on the base specificity of RNase Bm2 and the phylogenetic relationship of RNase T2 family enzymes.
authors.affiliation: Department of Microbiology, College of Pharmacy, Nihon University, Funabashi, Chiba, Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Itagaki
authors.forename: Hideki
authors.initials: H
authors.lastname: Koyama
authors.forename: Satoshi
authors.initials: S
authors.lastname: Daigo
authors.forename: Hiroko
authors.initials: H
authors.lastname: Kobayashi
authors.forename: Takashi
authors.initials: T
authors.lastname: Koyama
authors.forename: Masanori
authors.initials: M
authors.lastname: Iwama
authors.forename: Kazuko
authors.initials: K
authors.lastname: Ohgi
authors.forename: Masachika
authors.initials: M
authors.lastname: Irie
authors.forename: Norio
authors.initials: N
authors.lastname: Inokuchi
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis / Q000378:metabolism; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D000460:Chlorophyta / Q000145:classification / Q000201:enzymology*; D002851:Chromatography, High Pressure Liquid; D003001:Cloning, Molecular; D004247:DNA / Q000032:analysis / Q000096:biosynthesis; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015723:Gene Library; D005822:Genetic Vectors; D006868:Hydrolysis; D007202:Indicators and Reagents; D008969:Molecular Sequence Data; D010802:Phylogeny; D012313:RNA / Q000032:analysis / Q000302:isolation & purification; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012260:Ribonucleases / Q000737:chemistry* / Q000302:isolation & purification; D012697:Serine Endopeptidases / Q000737:chemistry
chemical_list: D000596:Amino Acids; D007202:Indicators and Reagents; D012313:RNA; D004247:DNA; D012260:Ribonucleases; D012697:Serine Endopeptidases; C036813:lysyl endopeptidase