A cDNA encoding a cold-induced glycine-rich RNA binding protein from Prunus avium expressed in embryonic axes

Abstract

A cDNA clone encoding a presumed full-length glycine-rich ribonucleic acid (RNA) binding protein was isolated from a λ-ZAP Express cDNA library generated from primarily nondormant Prunus avium (wild cherry) embryonic axes. The cDNA, designated Pa-RRM-GRP1 ( Prunus avium RNA recognition motif glycine-rich protein 1), contains a single N-terminal RNA recognition motif (RRM) and single C-terminal glycine-rich domain. The glycine-rich domain is unusually long at 91 amino acids, 58 of which are glycines. The 534-base pair (bp) open reading frame (ORF) of this clone encodes a 178-amino-acid polypeptide with a predicted molecular weight of 17.33 kDa and p I of 7.84. Comparative sequence alignment of Pa-RRM-GRP1 reveals extensive homology to known and presumed glycine-rich RNA binding proteins from angiosperms and gymnosperms. Genomic Southern blot analysis suggests that this gene exists as a single copy in P. avium. Expression of this gene in P. avium embryonic axes during low-temperature dormancy-breaking treatments was studied and found to be induced by cold (3 °C) using real-time PCR of total cDNA supported by Northern blot analysis of total RNA. Expression dropped during prolonged storage at 3 °C and was reduced to control levels by interruption of cold treatment by warming to 20 °C.