Staphylococcal Cassette Chromosome, or SCC elements, are a family of genomic islands found in S. aureus and closely related species. SCC elements that carry the mecA gene are called SCCmec and render S. aureus methicillin-resistant, creating the MRSA strains. Cch, the self-loading helicase encoded by SCCmec type IV, belongs to the pre-sensor II insert clade of AAA+ ATPases, as do the archaeal and eukaryotic MCM-family replicative helicases. The N-terminal domain carries Pfam:PF06048. The central domain (residues 157-438) contains an AAA+ ATPase fold. This domain is found at the C-terminal region, it is a winged helix-turn-helix (WH) domain typical of many dsDNA-binding proteins [1].

1: Staphylococcal SCCmec elements encode an active MCM-like helicase and thus may be replicative. Mir-Sanchis I, Roman CA, Misiura A, Pigli YZ, Boyle-Vavra S, Rice PA; Nat Struct Mol Biol. 2016; [Epub ahead of print] PMID:27571176