title: RNase 1 genes from the family Sciuridae define a novel rodent ribonuclease cluster.
abstract: The RNase A ribonucleases are a complex group of functionally diverse secretory proteins with conserved enzymatic activity. We have identified novel RNase 1 genes from four species of squirrel (order Rodentia, family Sciuridae). Squirrel RNase 1 genes encode typical RNase A ribonucleases, each with eight cysteines, a conserved CKXXNTF signature motif, and a canonical His(12)-Lys(41)-His(119) catalytic triad. Two alleles encode Callosciurus prevostii RNase 1, which include a Ser(18)<-->Pro, analogous to the sequence polymorphisms found among the RNase 1 duplications in the genome of Rattus exulans. Interestingly, although the squirrel RNase 1 genes are closely related to one another (77-95% amino acid sequence identity), the cluster as a whole is distinct and divergent from the clusters including RNase 1 genes from other rodent species. We examined the specific sites at which Sciuridae RNase 1s diverge from Muridae/Cricetidae RNase 1s and determined that the divergent sites are located on the external surface, with complete sparing of the catalytic crevice. The full significance of these findings awaits a more complete understanding of biological role of mammalian RNase 1s.
authors.affiliation: Laboratory of Allergic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, 20892, USA.
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Siegel
authors.forename: Caroline M
authors.initials: CM
authors.lastname: Percopo
authors.forename: Kimberly D
authors.initials: KD
authors.lastname: Dyer
authors.forename: Wei
authors.initials: W
authors.lastname: Zhao
authors.forename: V Louise
authors.initials: VL
authors.lastname: Roth
authors.forename: John M
authors.initials: JM
authors.lastname: Mercer
authors.forename: Helene F
authors.initials: HF
authors.lastname: Rosenberg
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015139:Blotting, Southern; D004247:DNA / Q000737:chemistry / Q000235:genetics; D014644:Genetic Variation; D008969:Molecular Sequence Data; D005810:Multigene Family; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D012259:Ribonuclease, Pancreatic / Q000235:genetics*; D012589:Sciuridae / Q000235:genetics* / Q000378:metabolism; D016415:Sequence Alignment
chemical_list: D004247:DNA; D012259:Ribonuclease, Pancreatic