RNase 1 genes from the family Sciuridae define a novel rodent ribonuclease cluster

• Published in: Mammalian genome 2009-12, Vol.20 (11-12), p.749-757
• Main Authors: Siegel, Steven J, Percopo, Caroline M, Dyer, Kimberly D, Zhao, Wei, Roth, V. Louise, Mercer, John M, Rosenberg, Helene F
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animal Genetics and Genomics; Animals; Base Sequence; Biomedical and Life Sciences; Blotting, Southern; Cell Biology; Cricetidae; DNA - chemistry; DNA - genetics; Genetic Variation; Human Genetics; Life Sciences; Molecular Sequence Data; Multigene Family; Muridae; Phylogeny; Polymerase Chain Reaction; Rattus exulans; Ribonuclease, Pancreatic - genetics; Rodentia; Sciuridae; Sciuridae - genetics; Sciuridae - metabolism; Sequence Alignment
• ISSN: 0938-8990; 1432-1777
• DOI: 10.1007/s00335-009-9215-4

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 His¹²-Lys⁴¹-His¹¹⁹ catalytic triad. Two alleles encode Callosciurus prevostii RNase 1, which include a Ser¹⁸↔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.