1i1q
From Proteopedia
STRUCTURE OF THE COOPERATIVE ALLOSTERIC ANTHRANILATE SYNTHASE FROM SALMONELLA TYPHIMURIUM
Structural highlights
Function[TRPE_SALTY] Part of a heterotetrameric complex that catalyzes the two-step biosynthesis of anthranilate, an intermediate in the biosynthesis of L-tryptophan. In the first step, the glutamine-binding beta subunit (TrpG) of anthranilate synthase (AS) provides the glutamine amidotransferase activity which generates ammonia as a substrate that, along with chorismate, is used in the second step, catalyzed by the large alpha subunit of AS (TrpE) to produce anthranilate. In the absence of TrpG, TrpE can synthesize anthranilate directly from chorismate and high concentrations of ammonia.[1] [TRPGD_SALTY] Part of a heterotetrameric complex that catalyzes the two-step biosynthesis of anthranilate, an intermediate in the biosynthesis of L-tryptophan. In the first step, the glutamine-binding beta subunit (TrpG) of anthranilate synthase (AS) provides the glutamine amidotransferase activity which generates ammonia as a substrate that, along with chorismate, is used in the second step, catalyzed by the large alpha subunit of AS (TrpE) to produce anthranilate. In the absence of TrpG, TrpE can synthesize anthranilate directly from chorismate and high concentrations of ammonia. In addition to synthesizing anthranilate, it also catalyzes the second step of the pathway, the transfer of the phosphoribosyl group of 5-phosphorylribose-1-pyrophosphate (PRPP) to anthranilate.[2] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedWe have determined the X-ray crystal structure of the cooperative anthranilate synthase heterotetramer from Salmonella typhimurium at 1.9 A resolution with the allosteric inhibitor l-tryptophan bound to a regulatory site in the TrpE subunit. Tryptophan binding orders a loop that in turn stabilizes the inactive T state of the enzyme by restricting closure of the active site cleft. Comparison with the structure of the unliganded, noncooperative anthranilate synthase heterotetramer from Sulfolobus solfataricus shows that the two homologs have completely different quarternary structures, even though their functional dimer pairs are structurally similar, consistent with differences in the cooperative behavior of the enzymes. The structural model rationalizes mutational and biochemical studies of the enzyme and establishes the structural differences between cooperative and noncooperative anthranilate synthase homologs. Structure of the cooperative allosteric anthranilate synthase from Salmonella typhimurium.,Morollo AA, Eck MJ Nat Struct Biol. 2001 Mar;8(3):243-7. PMID:11224570[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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