skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Direct observation of intermediates in the SufS cysteine desulfurase reaction reveals functional roles of conserved active-site residues

Journal Article · · Journal of Biological Chemistry

Iron-sulfur (Fe-S) clusters are necessary for the proper functioning of numerous metalloproteins. Fe-S cluster (Isc) and sulfur utilization factor (Suf) pathways are the key biosynthetic routes responsible for generating these Fe-S cluster prosthetic groups in Escherichia coli. Although Isc dominates under normal conditions, Suf takes over during periods of iron depletion and oxidative stress. Sulfur acquisition via these systems relies on the ability to remove sulfur from free cysteine using a cysteine desulfurase mechanism. In the Suf pathway, the dimeric SufS protein uses the cofactor pyridoxal 5'-phosphate (PLP) to abstract sulfur from free cysteine, resulting in the production of alanine and persulfide. Despite much progress, the stepwise mechanism by which this PLP-dependent enzyme operates remains unclear. Here, using rapid-mixing kinetics in conjunction with X-ray crystallography, we analyzed the pre-steady-state kinetics of this process while assigning early intermediates of the mechanism. We employed H123A and C364A SufS variants to trap Cys-aldimine and Cys-ketimine intermediates of the cysteine desulfurase reaction, enabling direct observations of these intermediates and associated conformational changes of the SufS active site. Of note, we propose that Cys-364 is essential for positioning the Cys-aldimine for Cα deprotonation, His-123 acts to protonate the Ala-enamine intermediate, and Arg-56 facilitates catalysis by hydrogen bonding with the sulfhydryl of Cys-aldimine. Our results, along with previous SufS structural findings, suggest a detailed model of the SufS-catalyzed reaction from Cys binding to C–S bond cleavage and indicate that Arg-56, His-123, and Cys-364 are critical SufS residues in this C–S bond cleavage pathway.

Research Organization:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES)
Contributing Organization:
Advanced Photon Source (APS), Argonne National Laboratory (ANL), Argonne, IL (US)
Grant/Contract Number:
S10_RR25528; S10_RR028976; W-31-109-Eng-38; GM112919
OSTI ID:
1577152
Journal Information:
Journal of Biological Chemistry, Vol. 294, Issue 33; ISSN 0021-9258
Publisher:
American Society for Biochemistry and Molecular BiologyCopyright Statement
Country of Publication:
United States
Language:
ENGLISH
Citation Metrics:
Cited by: 17 works
Citation information provided by
Web of Science

References (45)

A nifS -like Gene, csdB , Encodes an Escherichia coli Counterpart of Mammalian Selenocysteine Lyase : GENE CLONING, PURIFICATION, CHARACTERIZATION AND PRELIMINARY X-RAY CRYSTALLOGRAPHIC STUDIES journal May 1999
The E. coli SufS-SufE sulfur transfer system is more resistant to oxidative stress than IscS-IscU journal October 2012
Iron/sulfur proteins biogenesis in prokaryotes: Formation, regulation and diversity journal March 2013
Mechanism-Based Trapping of the Quinonoid Intermediate by Using the K276R Mutant of PLP-Dependent 3-Aminobenzoate Synthase PctV in the Biosynthesis of Pactamycin journal October 2015
Structure of a NifS Homologue:  X-ray Structure Analysis of CsdB, an Escherichia coli Counterpart of Mammalian Selenocysteine Lyase , journal February 2000
Reaction Mechanism and Molecular Basis for Selenium/Sulfur Discrimination of Selenocysteine Lyase journal February 2010
Mechanism for the Desulfurization of L-Cysteine Catalyzed by the nifS Gene Product journal April 1994
Free energy landscapes of prototropic tautomerism in pyridoxal 5′-phosphate schiff bases at the active site of an enzyme in aqueous medium journal May 2018
Analysis of the E. coli NifS CsdB protein at 2.0 Å reveals the structural basis for perselenide and persulfide intermediate formation journal February 2002
Controlling reaction specificity in pyridoxal phosphate enzymes journal November 2011
Structural Evidence for Dimer-Interface-Driven Regulation of the Type II Cysteine Desulfurase, SufS journal December 2018
Iron-sulfur clusters: ever-expanding roles journal April 2006
SufC: an unorthodox cytoplasmic ABC/ATPase required for [Fe-S] biogenesis under oxidative stress journal February 2003
Sulfur Mobilization in Cyanobacteria: THE CATALYTIC MECHANISM OF L-CYSTINE C-S LYASE (C-DES) FROM SYNECHOCYSTIS journal October 2006
Cysteine Sulfinate Desulfinase, a NIFS-like Protein of Escherichia coli with Selenocysteine Lyase and Cysteine Desulfurase Activities : GENE CLONING, PURIFICATION, AND CHARACTERIZATION OF A NOVEL PYRIDOXAL ENZYME journal September 1997
Kinetic and Structural Characterization of Slr0077/SufS, the Essential Cysteine Desulfurase from Synechocystis sp. PCC 6803 , journal September 2004
Snapshots of the Cystine Lyase C-DES during Catalysis: STUDIES IN SOLUTION AND IN THE CRYSTALLINE STATE journal October 2002
Genetic Analysis of the isc Operon in Escherichia coli Involved in the Biogenesis of Cellular Iron-Sulfur Proteins journal July 2001
SufE Transfers Sulfur from SufS to SufB for Iron-Sulfur Cluster Assembly journal March 2007
Structure of External Aldimine of Escherichia coli CsdB, an IscS/Nifs Homolog: Implications for Its Specificity toward Selenocysteine journal May 2002
Kinetic Analysis of Cysteine Desulfurase CD0387 from Synechocystis sp. PCC 6803: Formation of the Persulfide Intermediate journal December 2009
Pyridoxal Phosphate Enzymes: Mechanistic, Structural, and Evolutionary Considerations journal June 2004
Biogenesis of Fe-S Cluster by the Bacterial Suf System: SufS AND SufE FORM A NEW TYPE OF CYSTEINE DESULFURASE journal July 2003
A suf operon requirement for Fe-S cluster assembly during iron starvation in Escherichia coli: suf operon role during iron starvation journal April 2004
Crystal structure of the nickel–iron hydrogenase from Desulfovibrio gigas journal February 1995
Evidence for a Two-Base Mechanism Involving Tyrosine-265 from Arginine-219 Mutants of Alanine Racemase journal March 1999
Structure, mechanism, and substrate specificity of kynureninase journal November 2011
Chloroplast iron-sulfur cluster protein maturation requires the essential cysteine desulfurase CpNifS journal March 2007
MUSCLE: multiple sequence alignment with high accuracy and high throughput journal March 2004
Current Advances on Structure-Function Relationships of Pyridoxal 5′-Phosphate-Dependent Enzymes journal March 2019
Mechanistic characterization of sulfur transfer from cysteine desulfurase SufS to the iron-sulfur scaffold SufU in Bacillus subtilis journal January 2011
The SufE Protein and the SufBCD Complex Enhance SufS Cysteine Desulfurase Activity as Part of a Sulfur Transfer Pathway for Fe-S Cluster Assembly in Escherichia coli journal August 2003
Protected Sulfur Transfer Reactions by the Escherichia coli Suf System journal May 2013
SufE D74R Substitution Alters Active Site Loop Dynamics To Further Enhance SufE Interaction with the SufS Cysteine Desulfurase journal July 2015
pH Studies on the Mechanism of the Pyridoxal Phosphate-Dependent Dialkylglycine Decarboxylase journal January 1999
Crystal Structure of Bacillus subtilis Cysteine Desulfurase SufS and Its Dynamic Interaction with Frataxin and Scaffold Protein SufU journal July 2016
Escherichia coli SufE Sulfur Transfer Protein Modulates the SufS Cysteine Desulfurase through Allosteric Conformational Dynamics journal November 2013
Changes in Protein Dynamics in Escherichia coli SufS Reveal a Possible Conserved Regulatory Mechanism in Type II Cysteine Desulfurase Systems journal March 2018
Shared-intermediates in the biosynthesis of thio-cofactors: Mechanism and functions of cysteine desulfurases and sulfur acceptors journal June 2015
The CsdA cysteine desulphurase promotes Fe/S biogenesis by recruiting Suf components and participates to a new sulphur transfer pathway by recruiting CsdL (ex-YgdL), a ubiquitin-modifying-like protein: The E. coli CsdA cysteine desulphurase journal December 2009
Detection of a gem-diamine and a stable quinonoid intermediate in the reaction catalyzed by serine–glyoxylate aminotransferase from Hyphomicrobium methylovorum journal June 2009
Kinetic and Mutational Studies of Three NifS Homologs from Escherichia coli: Mechanistic Difference between L-Cysteine Desulfurase and L-Selenocysteine Lyase Reactions journal April 2000
Structural Changes during Cysteine Desulfurase CsdA and Sulfur Acceptor CsdE Interactions Provide Insight into the trans -Persulfuration journal August 2013
Mechanisms of iron–sulfur cluster assembly: the SUF machinery journal October 2005
Mechanisms of iron–sulfur cluster assembly: the SUF machinery journal November 2005

Cited By (1)

Snapshots of PLP‐substrate and PLP‐product external aldimines as intermediates in two types of cysteine desulfurase enzymes journal October 2019