Kinetic Isotope Effects and Hydrogen/Deuterium Exchange Reveal Large Conformational Changes During the Catalysis of the Clostridium acetobutylicum Spore Photoproduct Lyase.

ABSTRACT: Spore photoproduct lyase (SPL) catalyzes the direct reversal of a thymine dimer 5-thyminyl-5,6-dihydrothymine (i.e. the spore photoproduct (SP)) to two thymine residues in germinating endospores. Previous studies suggest that SPL from the bacterium Bacillus subtilis (Bs) harbors an unprecedented radical-transfer pathway starting with cysteine 141 proceeding through tyrosine 99. However, in SPL from the bacterium Clostridium acetobutylicum (Ca), the cysteine (at position 74) and the tyrosine are located on the opposite sides of a substrate-binding pocket that has to collapse to bring the two residues into proximity, enabling the C→Y radical passage as implied in SPL_(Bs) . To test this hypothesis, we adopted hydrogen/deuterium exchange mass spectrometry (HDX-MS) to show that C74

SUBMITTER: Yang L 

PROVIDER: S-EPMC5315627 | biostudies-literature | 2017 Jan

REPOSITORIES: biostudies-literature