BACH1, a novel helicase-like protein, interacts directly with BRCA1 and contributes to its DNA repair function

BRCA1 interacts in vivo with a novel protein, BACH1, a member of the DEAH h elicase family. BACH1 binds directly to the BRCT repeats of BRCA1.A BACH1 d erivative, bearing a mutation in a residue that was essential for catalytic function in other helicases, interfered with normal double-strand break re pair in a manner that was dependent on its BRCA1 binding function. Thus, BA CH1/BRCA1 complex formation contributes to a key BRCA1 activity. In additio n, germline BACH1 mutations affecting the helicase domain were detected in two early-onset breast cancer patients and not in 200 matched controls. Thu s, it is conceivable that, like BRCA1, BACH1 is a target of germline cancer -inducing mutations.