Vanadate-catalyzed photocleavage of the signature motif of an ATP-binding cassette (ABC) transporter.

ABSTRACT: The maltose transport complex of Escherichia coli, a member of the ATP-binding cassette (ABC) superfamily, is made up of two nucleotide-binding subunits, MalK(2), which hydrolyze ATP with positive cooperativity, and two transmembrane subunits, MalF and MalG. The ABC family is defined in part by the canonical signature motif LSGGQ whose exact function remains controversial. Taking advantage of the dual function of vanadate as a transition state analogue and as a photoactive chemical, we demonstrate that vanadate catalyzes the UV-dependent cleavage of the polypeptide backbone at both the LSGGQ motif and the nucleotide-binding, or Walker A, motif when it is trapped in the nucleotide-binding site of the bacterial maltose transporter. This highly specific cleavage pattern indicates that residue

SUBMITTER: Fetsch EE 

PROVIDER: S-EPMC124977 | biostudies-literature | 2002 Jul

REPOSITORIES: biostudies-literature