Calmodulin functions as an activator of Pur alpha binding to single-stranded purine-rich DNA elements (PUR elements)

Pur alpha is a single stranded DNA-binding protein and binds to a consensus sequence (GGN)n. We have reported that the DNA-binding activity of a singl e stranded cyclic AMP response element-binding protein (ssCRE-BP) is suppre ssed in cerebellum treated chronically with morphine, ssCRE-BP is identical to Pur alpha and the DNA binding activity of Pur alpha is markedly enhance d by a heat stable activator in the nuclear extract. In this report, we pur ified this activator. The amino acid composition and partial amino acid seq uence were determined to be identical to those of calmodulin (CaM), which e nhanced the binding of GST-Pur alpha to various PUR elements in the 5' non- coding regions of the neuropeptide Y, myelin basic protein and nicotinic Ac h receptor beta 4 subunit genes. The data suggest a novel gene expression p athway mediated by Ca/CaM-Pur alpha which may regulate a variety of genes i n addition to those regulated through the CREB pathway. (C) 1999 Academic P ress.