DNA binding properties of Saccharomyces cerevisiae chromatin associated ras-related protein Yp20

Abstract

Yp20 is an abundant 20 kDa chromatin associated protein which has been shown to be related antigenically to genuine H ras products. Using Southwestern blots we have demonstrated that Yp20 is a DNA binding protein. It is also shown that protein Yp20 like protein HM (an abundant thermostable 20 kDa DNA binding protein isolated from mitochondria) and like the 21 kDa autonomously replicating sequence binding factor II (ABFII) is able to introduce superhelical turns into circular relaxed DNA in the presence of DNA topoisomerase I activity. We suggest that this protein may be important for chromatin structure and function.