PURIFICATION OF AN OLIGO(DG)CENTER-DOTOLIGO(DC)-BINDING SEA-URCHIN NUCLEAR-PROTEIN, SUGF1 - A FAMILY OF G-STRING FACTORS INVOLVED IN GENE-REGULATION DURING DEVELOPMENT

Contiguous deoxyguanosine residues (G strings) have been implicated in regulation of gene expression in several organisms via the binding of G-string factors. Regulation of expression of the chicken adult beta- globin gene may involve the interplay between binding of an erythrocyt e-specific G-string factor, BGP1, and the stability of a positioned nu cleosome (C. D. Lewis, S. P. Clark, G. Felsenfeld, and H. Gould, Genes Dev. 2:863-873, 1988). We have purified a 59.5-kDa nuclear protein (s uGF1) from sea urchin embryos by DNA affinity chromatography. suGF1 ha s high binding affinity and specificity for oligo(dG).oligo(dC). The i dentity of the purified protein was confirmed by renaturation of seque nce-specific DNA-binding activity from a sodium dodecyl sulfate-polyac rylamide gel slice and by Southwestern (DNA-protein) blotting. suGF1 b inds in vitro to a G(11) string present in the H1-H4 intergenic region of a sea urchin early histone gene battery. This suGF1 DNA recognitio n site occurs within a homopurine-homopyrimidine stretch previously sh own to be incorporated into a positioned nucleosome core in vitro. DNa se I footprinting shows that suGF1 protects the same base pairs on the promoter of the chicken beta(A)-globin gene as does BGP1. We show tha t a G-string cis-regulatory element of a sea urchin cell lineage-speci fic gene LpS1 (M. Xiang, S. -Y. Lu, M. Musso, G. Karsenty, and W. H. K lein, Development 113:1345-1355, 1991) also represents a high-affinity recognition site for suGF1. suGF1 may be a member of a family of G-st ring factors involved in the regulation of expression of unrelated gen es during development of a number of different organisms.