PDBsum entry 1z7w

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Transferase PDB id
Protein chain
320 a.a. *
Waters ×172
* Residue conservation analysis
PDB id:
Name: Transferase
Title: Crystal structure of o-acetylserine sulfhydrylase from arabi thaliana
Structure: Cysteine synthase. Chain: a. Synonym: o-acetylserine sulfhydrylase, o-acetylserine (thio csase a, cs-a, oas-tl a, cys-3a, at.Oas.5-8. Engineered: yes
Source: Arabidopsis thaliana. Thale cress. Organism_taxid: 3702. Gene: oasa1, oas1. Expressed in: escherichia coli bl21(de3). Expression_system_taxid: 469008.
Biol. unit: Dimer (from PQS)
2.20Å     R-factor:   0.186     R-free:   0.209
Authors: E.R.Bonner,R.E.Cahoon,S.M.Knapke,J.M.Jez
Key ref:
E.R.Bonner et al. (2005). Molecular basis of cysteine biosynthesis in plants: structural and functional analysis of O-acetylserine sulfhydrylase from Arabidopsis thaliana. J Biol Chem, 280, 38803-38813. PubMed id: 16166087 DOI: 10.1074/jbc.M505313200
28-Mar-05     Release date:   20-Sep-05    
Go to PROCHECK summary

Protein chain
Pfam   ArchSchema ?
P47998  (CYSK1_ARATH) -  Cysteine synthase 1
322 a.a.
320 a.a.
Key:    PfamA domain  Secondary structure  CATH domain

 Gene Ontology (GO) functional annotation 
  GO annot!
  Cellular component     apoplast   10 terms 
  Biological process     aging   20 terms 
  Biochemical function     protein binding     4 terms  


DOI no: 10.1074/jbc.M505313200 J Biol Chem 280:38803-38813 (2005)
PubMed id: 16166087  
Molecular basis of cysteine biosynthesis in plants: structural and functional analysis of O-acetylserine sulfhydrylase from Arabidopsis thaliana.
E.R.Bonner, R.E.Cahoon, S.M.Knapke, J.M.Jez.
In plants, cysteine biosynthesis plays a central role in fixing inorganic sulfur from the environment and provides the only metabolic sulfide donor for the generation of methionine, glutathione, phytochelatins, iron-sulfur clusters, vitamin cofactors, and multiple secondary metabolites. O-Acetylserine sulfhydrylase (OASS) catalyzes the final step of cysteine biosynthesis, the pyridoxal 5'-phosphate (PLP)-dependent conversion of O-acetylserine into cysteine. Here we describe the 2.2 A resolution crystal structure of OASS from Arabidopsis thaliana (AtOASS) and the 2.7 A resolution structure of the AtOASS K46A mutant with PLP and methionine covalently linked as an external aldimine in the active site. Although the plant and bacterial OASS share a conserved set of amino acids for PLP binding, the structure of AtOASS reveals a difference from the bacterial enzyme in the positioning of an active site loop formed by residues 74-78 when methionine is bound. Site-directed mutagenesis, kinetic analysis, and ligand binding titrations probed the functional roles of active site residues. These experiments indicate that Asn(77) and Gln(147) are key amino acids for O-acetylserine binding and that Thr(74) and Ser(75) are involved in sulfur incorporation into cysteine. In addition, examination of the AtOASS structure and nearly 300 plant and bacterial OASS sequences suggest that the highly conserved beta8A-beta9A surface loop may be important for interaction with serine acetyltransferase, the other enzyme in cysteine biosynthesis. Initial protein-protein interaction experiments using AtOASS mutants targeted to this loop support this hypothesis.
  Selected figure(s)  
Figure 2.
FIGURE 2. Three-dimensional structure of AtOASS. A, ribbon diagram of the AtOASS dimer. Each monomer is colored either blue or green. PLP is shown as a yellow stick model. The N-terminal and C-terminal residues observed in the electron density of the structure are indicated with residue number in parenthesis. Secondary structure features are labeled. B, overlay of the C traces of AtOASS (green) and StOASS (orange) monomers. The arrows indicate regions of structural variation. C, stereoview of the AtOASS active site. PLP is covalently attached to Lys46 and is shown in the same orientation as A. Side chains of amino acids and the sulfate molecule bound at the active site are shown. Waters are drawn as red spheres. Hydrogen bonds are indicated by the dotted lines. D, schematic diagram of interactions between PLP and amino acids of AtOASS. W, water. Hydrogen bonds are shown as dashed lines with distances noted in Å. E, initial SIGMAA-weighted |2F[o] - F[c]| electron density (1.5 ) for the Schiff base formed between PLP and Lys46. All structural figures were generated using PyMol.
Figure 3.
FIGURE 3. Structure of the AtOASS K46A mutant. A, initial SIGMAA-weighted |2F[o] - F[c]| electron density (1.5 ) for the external aldimine formed between PLP and methionine. The final refined model is shown as a stick model. B, overlay of the C traces of the AtOASS K46A mutant (blue), StOASS (orange), and StOASS K41A mutant (magenta) structures. The active site PLP-methionine external aldimine molecules of the AtOASS (yellow) and StOASS (magenta) mutant structures are shown as stick models. In the StOASS K41A mutant, two loops corresponding to residues 74-78 and 98-102 shift toward the active site. C, stereoview of the AtOASS K46A active site. PLP forms an external aldimine with a methionine and is shown in the same orientation as Fig. 2, A and C. Side chains of active site residues are shown. Hydrogen bonds are indicated by the dotted lines. D, schematic diagram of active site interactions in the AtOASS K46A mutant. Hydrogen bonds are shown as dashed lines with distances noted in Å.
  The above figures are reprinted by permission from the ASBMB: J Biol Chem (2005, 280, 38803-38813) copyright 2005.  
  Figures were selected by an automated process.  

Literature references that cite this PDB file's key reference

  PubMed id Reference
19928859 E.Salsi, A.S.Bayden, F.Spyrakis, A.Amadasi, B.Campanini, S.Bettati, T.Dodatko, P.Cozzini, G.E.Kellogg, P.F.Cook, S.L.Roderick, and A.Mozzarelli (2010).
Design of O-acetylserine sulfhydrylase inhibitors by mimicking nature.
  J Med Chem, 53, 345-356.
PDB codes: 3iqg 3iqh 3iqi
20080815 H.Yi, A.Galant, G.E.Ravilious, M.L.Preuss, and J.M.Jez (2010).
Sensing sulfur conditions: simple to complex protein regulatory mechanisms in plant thiol metabolism.
  Mol Plant, 3, 269-279.  
20364282 H.Yi, G.E.Ravilious, A.Galant, H.B.Krishnan, and J.M.Jez (2010).
From sulfur to homoglutathione: thiol metabolism in soybean.
  Amino Acids, 39, 963-978.  
20429919 R.Shirzadian-Khorramabad, H.C.Jing, G.E.Everts, J.H.Schippers, J.Hille, and P.P.Dijkwel (2010).
A mutation in the cytosolic O-acetylserine (thiol) lyase induces a genome-dependent early leaf death phenotype in Arabidopsis.
  BMC Plant Biol, 10, 80.  
19181864 K.W.Lai, C.P.Yau, Y.C.Tse, L.Jiang, and W.K.Yip (2009).
Heterologous expression analyses of rice OsCAS in Arabidopsis and in yeast provide evidence for its roles in cyanide detoxification rather than in cysteine synthesis in vivo.
  J Exp Bot, 60, 993.  
19296828 R.A.Williams, G.D.Westrop, and G.H.Coombs (2009).
Two pathways for cysteine biosynthesis in Leishmania major.
  Biochem J, 420, 451-462.  
19213732 S.Kumaran, H.Yi, H.B.Krishnan, and J.M.Jez (2009).
Assembly of the cysteine synthase complex and the regulatory role of protein-protein interactions.
  J Biol Chem, 284, 10268-10275.  
18350570 K.Chinthalapudi, M.Kumar, S.Kumar, S.Jain, N.Alam, and S.Gourinath (2008).
Crystal structure of native O-acetyl-serine sulfhydrylase from Entamoeba histolytica and its complex with cysteine: structural evidence for cysteine binding and lack of interactions with serine acetyl transferase.
  Proteins, 72, 1222-1232.
PDB codes: 2pqm 3bm5
  17554175 C.Krishna, R.Jain, T.Kashav, D.Wadhwa, N.Alam, and S.Gourinath (2007).
Crystallization and preliminary crystallographic analysis of cysteine synthase from Entamoeba histolytica.
  Acta Crystallogr Sect F Struct Biol Cryst Commun, 63, 512-515.  
17853367 E.Pajuelo, J.A.Carrasco, L.C.Romero, M.A.Chamber, and C.Gotor (2007).
Evaluation of the metal phytoextraction potential of crop legumes. Regulation of the expression of O-acetylserine (thiol)lyase under metal stress.
  Plant Biol (Stuttg), 9, 672-681.  
17894825 G.Zocher, U.Wiesand, and G.E.Schulz (2007).
High resolution structure and catalysis of O-acetylserine sulfhydrylase isozyme B from Escherichia coli.
  FEBS J, 274, 5382-5389.
PDB code: 2v03
16735516 G.D.Westrop, G.Goodall, J.C.Mottram, and G.H.Coombs (2006).
Cysteine biosynthesis in Trichomonas vaginalis involves cysteine synthase utilizing O-phosphoserine.
  J Biol Chem, 281, 25062-25075.  
The most recent references are shown first. Citation data come partly from CiteXplore and partly from an automated harvesting procedure. Note that this is likely to be only a partial list as not all journals are covered by either method. However, we are continually building up the citation data so more and more references will be included with time. Where a reference describes a PDB structure, the PDB codes are shown on the right.