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Molecular mechanism of antibody-mediated activation of ?-galactosidase.

ABSTRACT: Binding of a single-chain Fv antibody to Escherichia coli ?-galactosidase (?-gal) is known to stabilize the enzyme and activate several inactive point mutants, historically called antibody-mediated enzyme formation mutants. To understand the nature of this activation, we have determined by electron cryo-microscopy the structure of the complex between ?-gal and the antibody scFv13R4. Our structure localizes the scFv13R4 binding site to the crevice between domains 1 and 3 in each ?-gal subunit. The mutations that scFv13R4 counteracts are located between the antibody binding site and the active site of ?-gal, at one end of the TIM-barrel that forms domain 3 where the substrate lactose is hydrolyzed. The mode of binding suggests how scFv stabilizes both the active site of ?-gal and the tetrameric state.

SUBMITTER: Vinothkumar KR

PROVIDER: S-EPMC3988998 | biostudies-literature | 2014 Apr

REPOSITORIES: biostudies-literature

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Molecular mechanism of antibody-mediated activation of β-galactosidase.

Vinothkumar Kutti R KR McMullan Greg G Henderson Richard R

Structure (London, England : 1993) 20140306 4

Binding of a single-chain Fv antibody to Escherichia coli β-galactosidase (β-gal) is known to stabilize the enzyme and activate several inactive point mutants, historically called antibody-mediated enzyme formation mutants. To understand the nature of this activation, we have determined by electron cryo-microscopy the structure of the complex between β-gal and the antibody scFv13R4. Our structure localizes the scFv13R4 binding site to the crevice between domains 1 and 3 in each β-gal subunit. Th ...[more]

PMID: 24613486

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