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Title: Enzyme That Makes You Cry–Crystal Structure of Lachrymatory Factor Synthase from Allium cepa

Abstract

The biochemical pathway that gives onions their savor is part of the chemical warfare against microbes and animals. This defense mechanism involves formation of a volatile lachrymatory factor (LF) ((Z)-propanethial S-oxide) that causes familiar eye irritation associated with onion chopping. LF is produced in a reaction catalyzed by lachrymatory factor synthase (LFS). The principles by which LFS facilitates conversion of a sulfenic acid substrate into LF have been difficult to experimentally examine owing to the inherent substrate reactivity and lability of LF. To shed light on the mechanism of LF production in the onion, we solved crystal structures of LFS in an apo-form and in complex with a substrate analogue, crotyl alcohol. The enzyme closely resembles the helix-grip fold characteristic for plant representatives of the START (star-related lipid transfer) domain-containing protein superfamily. By comparing the structures of LFS to that of the abscisic acid receptor, PYL10, a representative of the START protein superfamily, we elucidated structural adaptations underlying the catalytic activity of LFS. We also delineated the architecture of the active site, and based on the orientation of the ligand, we propose a mechanism of catalysis that involves sequential proton transfer accompanied by formation of a carbanion intermediate. These findingsmore » reconcile chemical and biochemical information regarding thioaldehyde S-oxide formation and close a long-lasting gap in understanding of the mechanism responsible for LF production in the onion.« less

Authors:
 [1];  [2];  [3]; ORCiD logo [4]; ORCiD logo [5]
  1. Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States
  2. Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States; College of Wooster, Wooster, Ohio, United States
  3. Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York, United States; Northeastern Collaborative Access Team, Argonne National Laboratory, Argonne, Illinois, United States
  4. Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States; Research Service, Louis Stokes Cleveland VA Medical Center, Cleveland, Ohio, United States; Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States
  5. Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States; Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
OTHER U.S. GOVERNMENTNIH
OSTI Identifier:
1408133
Resource Type:
Journal Article
Resource Relation:
Journal Name: ACS Chemical Biology; Journal Volume: 12; Journal Issue: 9
Country of Publication:
United States
Language:
ENGLISH
Subject:
59 BASIC BIOLOGICAL SCIENCES

Citation Formats

Silvaroli, Josie A., Pleshinger, Matthew J., Banerjee, Surajit, Kiser, Philip D., and Golczak, Marcin. Enzyme That Makes You Cry–Crystal Structure of Lachrymatory Factor Synthase from Allium cepa. United States: N. p., 2017. Web. doi:10.1021/acschembio.7b00336.
Silvaroli, Josie A., Pleshinger, Matthew J., Banerjee, Surajit, Kiser, Philip D., & Golczak, Marcin. Enzyme That Makes You Cry–Crystal Structure of Lachrymatory Factor Synthase from Allium cepa. United States. doi:10.1021/acschembio.7b00336.
Silvaroli, Josie A., Pleshinger, Matthew J., Banerjee, Surajit, Kiser, Philip D., and Golczak, Marcin. 2017. "Enzyme That Makes You Cry–Crystal Structure of Lachrymatory Factor Synthase from Allium cepa". United States. doi:10.1021/acschembio.7b00336.
@article{osti_1408133,
title = {Enzyme That Makes You Cry–Crystal Structure of Lachrymatory Factor Synthase from Allium cepa},
author = {Silvaroli, Josie A. and Pleshinger, Matthew J. and Banerjee, Surajit and Kiser, Philip D. and Golczak, Marcin},
abstractNote = {The biochemical pathway that gives onions their savor is part of the chemical warfare against microbes and animals. This defense mechanism involves formation of a volatile lachrymatory factor (LF) ((Z)-propanethial S-oxide) that causes familiar eye irritation associated with onion chopping. LF is produced in a reaction catalyzed by lachrymatory factor synthase (LFS). The principles by which LFS facilitates conversion of a sulfenic acid substrate into LF have been difficult to experimentally examine owing to the inherent substrate reactivity and lability of LF. To shed light on the mechanism of LF production in the onion, we solved crystal structures of LFS in an apo-form and in complex with a substrate analogue, crotyl alcohol. The enzyme closely resembles the helix-grip fold characteristic for plant representatives of the START (star-related lipid transfer) domain-containing protein superfamily. By comparing the structures of LFS to that of the abscisic acid receptor, PYL10, a representative of the START protein superfamily, we elucidated structural adaptations underlying the catalytic activity of LFS. We also delineated the architecture of the active site, and based on the orientation of the ligand, we propose a mechanism of catalysis that involves sequential proton transfer accompanied by formation of a carbanion intermediate. These findings reconcile chemical and biochemical information regarding thioaldehyde S-oxide formation and close a long-lasting gap in understanding of the mechanism responsible for LF production in the onion.},
doi = {10.1021/acschembio.7b00336},
journal = {ACS Chemical Biology},
number = 9,
volume = 12,
place = {United States},
year = 2017,
month = 7
}