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Title: Crystal Structure and Functional Analysis of Homocitrate Synthase, an Essential Enzyme in Lysine Biosynthesis

Abstract

Homocitrate synthase (HCS) catalyzes the first and committed step in lysine biosynthesis in many fungi and certain Archaea and is a potential target for antifungal drugs. Here we report the crystal structure of the HCS apoenzyme from Schizosaccharomyces pombe and two distinct structures of the enzyme in complex with the substrate 2-oxoglutarate (2-OG). The structures reveal that HCS forms an intertwined homodimer stabilized by domain-swapping between the N- and C-terminal domains of each monomer. The N-terminal catalytic domain is composed of a TIM barrel fold in which 2-OG binds via hydrogen bonds and coordination to the active site divalent metal ion, whereas the C-terminal domain is composed of mixed {alpha}/{beta} topology. In the structures of the HCS apoenzyme and one of the 2-OG binary complexes, a lid motif from the C-terminal domain occludes the entrance to the active site of the neighboring monomer, whereas in the second 2-OG complex the lid is disordered, suggesting that it regulates substrate access to the active site through its apparent flexibility. Mutations of the active site residues involved in 2-OG binding or implicated in acid-base catalysis impair or abolish activity in vitro and in vivo. Together, these results yield new insights into the structuremore » and catalytic mechanism of HCSs and furnish a platform for developing HCS-selective inhibitors.« less

Authors:
; ; ; ;
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1006066
Resource Type:
Journal Article
Journal Name:
J. Biol. Chem.
Additional Journal Information:
Journal Volume: 284; Journal Issue: (51) ; 12, 2009; Journal ID: ISSN 0021-9258
Country of Publication:
United States
Language:
ENGLISH
Subject:
08 HYDROGEN; 36 MATERIALS SCIENCE; BIOSYNTHESIS; CATALYSIS; CRYSTAL STRUCTURE; ENZYMES; FLEXIBILITY; FUNCTIONAL ANALYSIS; FUNGI; HYDROGEN; IN VITRO; IN VIVO; LYSINE; MUTATIONS; RESIDUES; SUBSTRATES; TARGETS; TOPOLOGY

Citation Formats

Bulfer, Stacie L, Scott, Erin M, Couture, Jean-François, Pillus, Lorraine, Trievel, Raymond C, Michigan), and UCSD). Crystal Structure and Functional Analysis of Homocitrate Synthase, an Essential Enzyme in Lysine Biosynthesis. United States: N. p., 2010. Web. doi:10.1074/jbc.M109.046821.
Bulfer, Stacie L, Scott, Erin M, Couture, Jean-François, Pillus, Lorraine, Trievel, Raymond C, Michigan), & UCSD). Crystal Structure and Functional Analysis of Homocitrate Synthase, an Essential Enzyme in Lysine Biosynthesis. United States. https://doi.org/10.1074/jbc.M109.046821
Bulfer, Stacie L, Scott, Erin M, Couture, Jean-François, Pillus, Lorraine, Trievel, Raymond C, Michigan), and UCSD). 2010. "Crystal Structure and Functional Analysis of Homocitrate Synthase, an Essential Enzyme in Lysine Biosynthesis". United States. https://doi.org/10.1074/jbc.M109.046821.
@article{osti_1006066,
title = {Crystal Structure and Functional Analysis of Homocitrate Synthase, an Essential Enzyme in Lysine Biosynthesis},
author = {Bulfer, Stacie L and Scott, Erin M and Couture, Jean-François and Pillus, Lorraine and Trievel, Raymond C and Michigan) and UCSD)},
abstractNote = {Homocitrate synthase (HCS) catalyzes the first and committed step in lysine biosynthesis in many fungi and certain Archaea and is a potential target for antifungal drugs. Here we report the crystal structure of the HCS apoenzyme from Schizosaccharomyces pombe and two distinct structures of the enzyme in complex with the substrate 2-oxoglutarate (2-OG). The structures reveal that HCS forms an intertwined homodimer stabilized by domain-swapping between the N- and C-terminal domains of each monomer. The N-terminal catalytic domain is composed of a TIM barrel fold in which 2-OG binds via hydrogen bonds and coordination to the active site divalent metal ion, whereas the C-terminal domain is composed of mixed {alpha}/{beta} topology. In the structures of the HCS apoenzyme and one of the 2-OG binary complexes, a lid motif from the C-terminal domain occludes the entrance to the active site of the neighboring monomer, whereas in the second 2-OG complex the lid is disordered, suggesting that it regulates substrate access to the active site through its apparent flexibility. Mutations of the active site residues involved in 2-OG binding or implicated in acid-base catalysis impair or abolish activity in vitro and in vivo. Together, these results yield new insights into the structure and catalytic mechanism of HCSs and furnish a platform for developing HCS-selective inhibitors.},
doi = {10.1074/jbc.M109.046821},
url = {https://www.osti.gov/biblio/1006066}, journal = {J. Biol. Chem.},
issn = {0021-9258},
number = (51) ; 12, 2009,
volume = 284,
place = {United States},
year = {Tue Jan 12 00:00:00 EST 2010},
month = {Tue Jan 12 00:00:00 EST 2010}
}