Structure of SAICAR synthase from Thermotoga maritima at 2.2 angstroms reveals an unusual covalent dimer.
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.
Zhang
Rongguang
R
Biosciences Division, Midwest Center for Structural Genomics, Structural Biology Center, Argonne National Laboratory, Argonne, IL 60439, USA.
Skarina
Tatiana
T
Evdokimova
Elena
E
Edwards
Aled
A
Savchenko
Alexei
A
Laskowski
Roman
R
Cuff
Marianne E
ME
Joachimiak
Andrzej
A
D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D017124:Conserved Sequence; D003460:Crystallization; D019281:Dimerization; D008969:Molecular Sequence Data; D010453:Peptide Synthases / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D020124:Thermotoga maritima / Q000201:enzymology*
D011994:Recombinant Proteins; D010453:Peptide Synthases; C022379:phosphoribosylaminoimidazole-succinocarboxamide synthetase