Abstract
Cold-shock induced RNA binding protein family in Anabaena sp. PCC 7120 has an RNA recognition motif (RRM). In vitro RNA binding assay showed that the affinity to homopolymers of RbpA1 containing C-terminal glycine-rich domain was: poly(U) > poly(G) > poly(A) > poly(C), and the same result was obtained with RbpD lacking glycine-rich domain. Affinity of RbpG containing C-terminal long region was: poly(C) > poly(U) > poly(A) > poly(G). The R83E point mutant of RbpA1RRM84, an 84 amino acids protein containing RbpA1 RRM, was shown to lack affinity to poly(G). But in the present using full-length RbpA1 or RbpD constructs, point mutation of Arg, did not affect binding affinity. Though RbpA1 protein and RbpA1RRM84 protein showed the same tendency of binding to poly(A), poly(C) and poly(G), binding affinity was stronger in RbpA1. This suggests that the C-terminal region of RbpA1 is important in increasing binding affinity.
