Albany 2013: Book of Abstracts
June 11-15 2013
©Adenine Press (2012)
Architectural role of HMO1 in bending, bridging and compacting DNA
HMO1 proteins are abundant Saccharomyces cerevisiae (yeast) High Mobility Group Box (HMGB) protein ( Kamau, Bauerla & Grove, 2004).HMGB proteins are nuclear proteins which are known to be architectural proteins (Travers, 2003). HMO1 possesses two HMGB box domains. It has been reported that double box HMGB proteins induce strong bends upon binding to DNA. It is also believed that they play an essential role in reorganizing chromatin and therefore are likely to be involved in gene activation. To characterize DNA binding we combine single molecule stretching experiments and AFM imaging of HMO1 proteins bound to DNA. By stretching DNA bound to HMO1, we determine the dissociation constant, measure protein induced average DNA bending angles and determine the rate at which torsional constraint of the DNA is released by the protein. To further investigate the local nature of the binding, AFM images of HMO1-DNA complexes are imaged, and we probe the behavior of these complexes as a function of protein concentration. The results show that at lower concentrations, HMO1 preferentially binds to the ends of the double helix and links separate DNA strands. At higher concentrations HMO1 induces formation of a complex network that reorganizes DNA. Although HMG nuclear proteins are under intense investigation, little is known about HMO1. Our studies suggest that HMO1 proteins may facilitate interactions between multiple DNA molecules.
Travers AA. (2003) Priming the nucleosome: a role for HMGB proteins?, EMBO Rep 4, 131-6.