The Sulfolobus shibatae Ssh7a and Ssh7b proteins have been separately overproduced in Escherichia coli and purified using a simple procedure which includes a heat treatment step. The recombinant and native Ssh7 proteins are similar in the ability to bind both negatively supercoiled and relaxed DNAs. In addition, the recombinant Ssh7a resembles the native Ssh7 protein in constraining negative DNA supercoils. Our data suggest that the two isoforms of Ssh7 interact with DNA in a similar fashion, and the methylation state of Ssh7 interact with DNA in a similar fashion, and the methylation state of Ssh7 does not affect DNA binding and supercoil constraining by the protein.