Structure of SAICAR synthase from Thermotoga maritima at 2.2 angstroms reveals an unusual covalent dimer

Acta Crystallogr Sect F Struct Biol Cryst Commun. 2006 Apr 1;62(Pt 4):335-9. doi: 10.1107/S1744309106009651. Epub 2006 Mar 25.


As a part of a structural genomics program, the 2.2 angstroms resolution crystal structure of the PurC gene product from Thermotoga maritima has been solved. This 26.2 kDa protein belongs to the phophoribosylaminoimidazole-succinocarboxamide or SAICAR synthase family of enzymes, the members of which are involved in de novo purine biosynthesis. SAICAR synthase can be divided into three subdomains: two alpha+beta regions exhibiting structural homology with ATP-binding proteins and a carboxy-terminal subdomain of two alpha-helices. The asymmetric unit contains two copies of the protein which are covalently linked by a disulfide bond between Cys126(A) and Cys126(B). This 230-amino-acid protein exhibits high structural homology with SAICAR synthase from baker's yeast. The protein structure is described and compared with that of the ATP-SAICAR synthase complex from yeast.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Cloning, Molecular
  • Conserved Sequence
  • Crystallization
  • Dimerization
  • Molecular Sequence Data
  • Peptide Synthases / chemistry*
  • Peptide Synthases / isolation & purification
  • Peptide Synthases / metabolism
  • Protein Structure, Secondary
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / isolation & purification
  • Recombinant Proteins / metabolism
  • Saccharomyces cerevisiae / enzymology
  • Sequence Alignment
  • Sequence Homology, Amino Acid
  • Thermotoga maritima / enzymology*


  • Recombinant Proteins
  • Peptide Synthases
  • phosphoribosylaminoimidazole-succinocarboxamide synthetase