|Gene:||thiG||Accession Number: BSU11690 (MetaCyc)|
Species: Bacillus subtilis subtilis 168
Thiazole synthase (ThiG) catalyzes a very complex reaction that produces the thiazole moiety of thiamin diphosphate. The enzyme requires three inputs - 1-deoxy-D-xylulose 5-phosphate (DXP), 2-iminoacetate, and a carboxy-adenylated-[ThiS sulfur-carrier protein] [Park03b].
Based on current understanding, the reaction starts when DXP binds to lysine 96 of the thiazole synthase, forming an imine that tautomerizes to aminoketone [Dorrestein04]. Addition of the ThiS-thiocarboxylate, (formed separately by reactions catalyzed by ThiF and IscS) is followed by an S/O acyl shift and loss of water, where the ThiS-thiocarboxylate sulfur is exchanged with an oxygen from DXP [Dorrestein04a]. In the next step the ThiS protein leaves the complex and 2-iminoacetate (formed by ThiO from glycine) is added. At this point a cyclization occurs via a transimination that involves the release of ThiG, producing the final product of the enzyme, 2-[(2R,5Z)-(2-carboxy-4-methylthiazol-5(2H)-ylidene]ethyl phosphate [Hazra09].
|Map Position: [1,245,041 -> 1,245,811]|
Molecular Weight of Polypeptide: 27.022 kD (from nucleotide sequence)
Unification Links: DBTBS Operons:thiG , Entrez:2633523 , GenoList (SubtiList):BSU11690 , GOA:O31618 , Mint:MINT-8365876 , Protein Model Portal:O31618 , SMR:O31618 , String:224308.BSU11690 , String:BSU11690 , SubtilisWiki:thiG , SubtiWiki:thiG , UniProt:O31618
|Biological Process:||GO:0008152 - metabolic process
GO:0009228 - thiamine biosynthetic process [GOA00, GOA01a]
|Molecular Function:||GO:0003824 - catalytic activity
GO:0016829 - lyase activity [GOA00]
|Cellular Component:||GO:0005737 - cytoplasm [GOA07, GOA00]|
Enzymatic reaction of: thiazole synthase
EC Number: 22.214.171.124
1-deoxy-D-xylulose 5-phosphate + 2-iminoacetate + a thiocarboxy-adenylated-[ThiS-Protein] <=> 2-[(2R,5Z)-(2-carboxy-4-methylthiazol-5(2H)-ylidene]ethyl phosphate + a ThiS sulfur-carrier protein + 2 H2O
The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the Enzyme Commission system.
The reaction is favored in the direction shown.
Dorrestein04: Dorrestein PC, Zhai H, Taylor SV, McLafferty FW, Begley TP (2004). "The biosynthesis of the thiazole phosphate moiety of thiamin (vitamin B1): the early steps catalyzed by thiazole synthase." J Am Chem Soc 126(10);3091-6. PMID: 15012138
Dorrestein04a: Dorrestein PC, Zhai H, McLafferty FW, Begley TP (2004). "The biosynthesis of the thiazole phosphate moiety of thiamin: the sulfur transfer mediated by the sulfur carrier protein ThiS." Chem Biol 11(10);1373-81. PMID: 15489164
Hazra09: Hazra A, Chatterjee A, Begley TP (2009). "Biosynthesis of the thiamin thiazole in Bacillus subtilis: identification of the product of the thiazole synthase-catalyzed reaction." J Am Chem Soc 131(9);3225-9. PMID: 19216519
Park03b: Park JH, Dorrestein PC, Zhai H, Kinsland C, McLafferty FW, Begley TP (2003). "Biosynthesis of the thiazole moiety of thiamin pyrophosphate (vitamin B1)." Biochemistry 42(42);12430-8. PMID: 14567704
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