Cockayne syndrome (CS) is a rare inherited human genetic disorder char-acterized by developmental abnormalities, UV sensitivity, and premature aging. The CS group B (CSB) protein belongs to the SNF2-family of DNA-dependent ATPases and is implicated in transcription elongation, transcription coupled repair, and base excision repair. It is a DNA stimula-ted ATPase and remodels chromatin in vitro. We demonstrate for the first time that full-length CSB positively cooperates in ATP hydrolysis as a function of protein concentration
