Serine Acetyltransferase- Complex with Cysteine

Experimental Data Snapshot

  • Resolution: 1.85 Å
  • R-Value Free: 0.261 
  • R-Value Work: 0.198 
  • R-Value Observed: 0.201 

wwPDB Validation   3D Report Full Report

This is version 1.4 of the entry. See complete history


Structure of Serine Acetyltransferase in Complexes with CoA and its Cysteine Feedback Inhibitor

Olsen, L.R.Huang, B.Vetting, M.W.Roderick, S.L.

(2004) Biochemistry 43: 6013-6019

  • DOI: https://doi.org/10.1021/bi0358521
  • Primary Citation of Related Structures:  
    1SSM, 1SSQ, 1SST

  • PubMed Abstract: 

    Serine acetyltransferase (SAT, EC catalyzes the CoA-dependent acetylation of the side chain hydroxyl group of l-serine to form O-acetylserine, as the first step of a two-step biosynthetic pathway in bacteria and plants leading to the formation of l-cysteine. This reaction represents a key metabolic point of regulation for the cysteine biosynthetic pathway due to its feedback inhibition by cysteine. We have determined the X-ray crystal structure of Haemophilus influenzae SAT in complexes with CoA and its cysteine feedback inhibitor. The enzyme is a 175 kDa hexamer displaying the characteristic left-handed parallel beta-helix (LbetaH) structural domain of the hexapeptide acyltransferase superfamily of enzymes. Cysteine is bound in a crevice between adjacent LbetaH domains and underneath a loop excluded from the coiled LbetaH. The proximity of its thiol group to the thiol group of CoA derived from superimposed models of the cysteine and CoA complexes confirms that cysteine is bound at the active site. Analysis of the contacts of SAT with cysteine and CoA and the conformational differences that distinguish these complexes provides a structural basis for cysteine feedback inhibition, which invokes competition between cysteine and serine binding and a cysteine-induced conformational change of the C-terminal segment of the enzyme that excludes binding of the cofactor.

  • Organizational Affiliation

    Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, USA.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Serine acetyltransferaseA,
B [auth D]
267Haemophilus influenzaeMutation(s): 1 
Gene Names: CYSEHI0606
Find proteins for P43886 (Haemophilus influenzae (strain ATCC 51907 / DSM 11121 / KW20 / Rd))
Explore P43886 
Go to UniProtKB:  P43886
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP43886
Sequence Annotations
  • Reference Sequence
Small Molecules
Binding Affinity Annotations 
IDSourceBinding Affinity
CYS Binding MOAD:  1SSQ Ki: 1000 (nM) from 1 assay(s)
PDBBind:  1SSQ Ki: 1000 (nM) from 1 assay(s)
Experimental Data & Validation

Experimental Data

  • Resolution: 1.85 Å
  • R-Value Free: 0.261 
  • R-Value Work: 0.198 
  • R-Value Observed: 0.201 
  • Space Group: H 3
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 97.524α = 90
b = 97.524β = 90
c = 108.457γ = 120
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling

Structure Validation

View Full Validation Report

Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2004-06-01
    Type: Initial release
  • Version 1.1: 2008-04-29
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Derived calculations, Version format compliance
  • Version 1.3: 2021-10-27
    Changes: Database references, Derived calculations
  • Version 1.4: 2023-08-23
    Changes: Data collection, Refinement description