Closed fumarase C active site structures reveal SS Loop residue contribution in catalysis.

08:00 EDT 12th September 2019 | BioPortfolio

Summary of "Closed fumarase C active site structures reveal SS Loop residue contribution in catalysis."

Fumarase C catalyzes the reversible conversion of fumarate to S-malate. Previous structural investigations within the superfamily have reported a dynamic structural segment, termed the SS Loop. To date, active site asymmetry has raised the question of how SS Loop placement affects participation of key residues during the reaction. Herein, we report structural and kinetic analyses from E. coli fumarase C variants to understand the contribution of SS Loop residues S318, K324 and N326. High-resolution X-ray crystallographic results reveal three distinct fumarase C active site conformations, disordered-open, ordered-open, and the newly discovered ordered-closed. Surprisingly, each SS Loop variant has unaffected Michaelis constants coupled to reductions in turnover number. Based upon our structural and functional analyses, we propose structural and catalytic roles for each of the aforementioned residues.


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This article was published in the following journal.

Name: FEBS letters
ISSN: 1873-3468


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