Crystal structure of active site mutant of SQ Isomerase (YihS-H248A) from Salmonella enterica in complex with sulfofructose (SF)

Experimental Data Snapshot

  • Resolution: 2.13 Å
  • R-Value Free: 0.201 
  • R-Value Work: 0.180 
  • R-Value Observed: 0.181 

wwPDB Validation   3D Report Full Report

Ligand Structure Quality Assessment 

This is version 1.1 of the entry. See complete history


Molecular Basis of Sulfosugar Selectivity in Sulfoglycolysis.

Sharma, M.Abayakoon, P.Epa, R.Jin, Y.Lingford, J.P.Shimada, T.Nakano, M.Mui, J.W.Ishihama, A.Goddard-Borger, E.D.Davies, G.J.Williams, S.J.

(2021) ACS Cent Sci 7: 476-487

  • DOI: https://doi.org/10.1021/acscentsci.0c01285
  • Primary Citation of Related Structures:  
    7AG1, 7AG4, 7AG6, 7AG7, 7AGH, 7AGK, 7NE2

  • PubMed Abstract: 

    The sulfosugar sulfoquinovose (SQ) is produced by essentially all photosynthetic organisms on Earth and is metabolized by bacteria through the process of sulfoglycolysis. The sulfoglycolytic Embden-Meyerhof-Parnas pathway metabolizes SQ to produce dihydroxyacetone phosphate and sulfolactaldehyde and is analogous to the classical Embden-Meyerhof-Parnas glycolysis pathway for the metabolism of glucose-6-phosphate, though the former only provides one C3 fragment to central metabolism, with excretion of the other C3 fragment as dihydroxypropanesulfonate. Here, we report a comprehensive structural and biochemical analysis of the three core steps of sulfoglycolysis catalyzed by SQ isomerase, sulfofructose (SF) kinase, and sulfofructose-1-phosphate (SFP) aldolase. Our data show that despite the superficial similarity of this pathway to glycolysis, the sulfoglycolytic enzymes are specific for SQ metabolites and are not catalytically active on related metabolites from glycolytic pathways. This observation is rationalized by three-dimensional structures of each enzyme, which reveal the presence of conserved sulfonate binding pockets. We show that SQ isomerase acts preferentially on the β-anomer of SQ and reversibly produces both SF and sulforhamnose (SR), a previously unknown sugar that acts as a derepressor for the transcriptional repressor CsqR that regulates SQ-utilization. We also demonstrate that SF kinase is a key regulatory enzyme for the pathway that experiences complex modulation by the metabolites SQ, SLA, AMP, ADP, ATP, F6P, FBP, PEP, DHAP, and citrate, and we show that SFP aldolase reversibly synthesizes SFP. This body of work provides fresh insights into the mechanism, specificity, and regulation of sulfoglycolysis and has important implications for understanding how this biochemistry interfaces with central metabolism in prokaryotes to process this major repository of biogeochemical sulfur.

  • Organizational Affiliation

    York Structural Biology Laboratory, Department of Chemistry, University of York, York YO10 5DD, U.K.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Sulfoquinovose isomerase433Salmonella enterica subsp. enterica serovar Typhimurium str. LT2Mutation(s): 1 
Gene Names: yihSSTM4021
Find proteins for Q8ZKT7 (Salmonella typhimurium (strain LT2 / SGSC1412 / ATCC 700720))
Explore Q8ZKT7 
Go to UniProtKB:  Q8ZKT7
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ8ZKT7
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.13 Å
  • R-Value Free: 0.201 
  • R-Value Work: 0.180 
  • R-Value Observed: 0.181 
  • Space Group: I 1 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 87.818α = 90
b = 136.827β = 95.35
c = 230.036γ = 90
Software Package:
Software NamePurpose
Aimlessdata scaling
PDB_EXTRACTdata extraction
xia2data reduction

Structure Validation

View Full Validation Report

Ligand Structure Quality Assessment 

Entry History & Funding Information

Deposition Data

Funding OrganizationLocationGrant Number
Leverhulme TrustUnited KingdomRPG-2017-190

Revision History  (Full details and data files)

  • Version 1.0: 2021-04-14
    Type: Initial release
  • Version 1.1: 2024-01-31
    Changes: Data collection, Database references, Refinement description