A Protocol for Assaying the ATPase Activity of Recombinant Cohesin Holocomplexes

Cohesin and other members of the structural maintenance of chromosomes (SMC)-kleisin family such as condensin and Smc5-6, as well as central players in genome function and structure such as topoisomerases, DNA and RNA polymerases, and DNA repair enzymes contain nucleotide binding domains (NBD) which bind and eventually cleave ATP. The released energy is harnessed in various ways by these enzymes in order to fulfill their essential functions. However, unlike other enzymes, Smc-kleisin complexes-well sized, elongated and multisubunit in nature-have only recently been purified as holocomplexes. This progress offers both the opportunity and the challenge to determine in detail the potency of the ATPase activity of these large protein assemblies-typically exceeding 0.5 MDa in molecular weight-and examine its mechanistic features. We describe here in further detail a combined comprehensive protocol which we have successfully employed before for assaying the ATPase activity of recombinant budding yeast cohesin holocomplexes. We believe that with small and appropriate modifications the methods described here should be applicable to other ATPase complexes.