2VDJ

Crystal Structure of Homoserine O-acetyltransferase (metA) from Bacillus Cereus with Homoserine


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2 Å
  • R-Value Free: 0.246 
  • R-Value Work: 0.199 

wwPDB Validation 3D Report Full Report


This is version 1.3 of the entry. See complete history

Literature

A Single Amino Acid Change is Responsible for Evolution of Acyltransferase Specificity in Bacterial Methionine Biosynthesis.

Zubieta, C.Arkus, K.A.J.Cahoon, R.E.Jez, J.M.

(2008) J.Biol.Chem. 283: 7561

  • DOI: 10.1074/jbc.M709283200

  • PubMed Abstract: 
  • Bacteria and yeast rely on either homoserine transsuccinylase (HTS, metA) or homoserine transacetylase (HTA; met2) for the biosynthesis of methionine. Although HTS and HTA catalyze similar chemical reactions, these proteins are typically unrelated in ...

    Bacteria and yeast rely on either homoserine transsuccinylase (HTS, metA) or homoserine transacetylase (HTA; met2) for the biosynthesis of methionine. Although HTS and HTA catalyze similar chemical reactions, these proteins are typically unrelated in both sequence and three-dimensional structure. Here we present the 2.0 A resolution x-ray crystal structure of the Bacillus cereus metA protein in complex with homoserine, which provides the first view of a ligand bound to either HTA or HTS. Surprisingly, functional analysis of the B. cereus metA protein shows that it does not use succinyl-CoA as a substrate. Instead, the protein catalyzes the transacetylation of homoserine using acetyl-CoA. Therefore, the B. cereus metA protein functions as an HTA despite greater than 50% sequence identity with bona fide HTS proteins. This result emphasizes the need for functional confirmation of annotations of enzyme function based on either sequence or structural comparisons. Kinetic analysis of site-directed mutants reveals that the B. cereus metA protein and the E. coli HTS share a common catalytic mechanism. Structural and functional examination of the B. cereus metA protein reveals that a single amino acid in the active site determines acetyl-CoA (Glu-111) versus succinyl-CoA (Gly-111) specificity in the metA-like of acyltransferases. Switching of this residue provides a mechanism for evolving substrate specificity in bacterial methionine biosynthesis. Within this enzyme family, HTS and HTA activity likely arises from divergent evolution in a common structural scaffold with conserved catalytic machinery and homoserine binding sites.


    Organizational Affiliation

    Donald Danforth Plant Science Center, St. Louis, Missouri 63132, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
HOMOSERINE O-SUCCINYLTRANSFERASE
A
301Bacillus cereus (strain ATCC 10987 / NRS 248)Mutation(s): 0 
Gene Names: metAA (metA)
EC: 2.3.1.31
Find proteins for Q72X44 (Bacillus cereus (strain ATCC 10987 / NRS 248))
Go to UniProtKB:  Q72X44
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
SO4
Query on SO4

Download SDF File 
Download CCD File 
A
SULFATE ION
O4 S
QAOWNCQODCNURD-UHFFFAOYSA-L
 Ligand Interaction
HSE
Query on HSE

Download SDF File 
Download CCD File 
A
L-HOMOSERINE
C4 H9 N O3
UKAUYVFTDYCKQA-VKHMYHEASA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2 Å
  • R-Value Free: 0.246 
  • R-Value Work: 0.199 
  • Space Group: P 41 2 2
Unit Cell:
Length (Å)Angle (°)
a = 96.390α = 90.00
b = 96.390β = 90.00
c = 75.580γ = 90.00
Software Package:
Software NamePurpose
XSCALEdata scaling
XDSdata reduction
REFMACrefinement
PHASERphasing

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2008-01-22
    Type: Initial release
  • Version 1.1: 2011-07-13
    Type: Advisory, Version format compliance
  • Version 1.2: 2017-08-23
    Type: Data collection
  • Version 1.3: 2019-04-10
    Type: Data collection, Source and taxonomy