4n8q | pdb_00004n8q

Alternative substrates of Mycobacterium tuberculosis anthranilate phosphoribosyl transferase

spinqualitylabelsall models 4n8q, resolution 2.08Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4n8q is a 2 chain structure with sequence from Mycobacterium tuberculosis. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.08Å Ligands: FA0 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function TRPD_MYCTU Publication Abstract from PubMed Anthranilate phosphoribosyltransferase (AnPRT), required for the biosynthesis of tryptophan, is essential for the virulence of Mycobacterium tuberculosis (Mtb). AnPRT catalyses the Mg2+-dependent transfer of a phosphoribosyl group from 5'-phosphoribosyl 1'-pyrophosphate (PRPP) to anthranilate to form 5'-phosphoribosyl anthranilate (PRA). Mtb-AnPRT was shown to catalyse a sequential reaction and significant substrate inhibition by anthranilate was observed. Antimycobacterial fluoroanthranilates and methyl-substituted analogues were shown to act as alternative substrates for Mtb-AnPRT, producing the corresponding substituted PRA products. Structures of the enzyme complexed with anthranilate analogues reveal two distinct binding sites for anthranilate. One site is located over 8 A from PRPP at the entrance to a tunnel leading to the active site, whereas in the second, inner site anthranilate is adjacent to PRPP, in a catalytically relevant position. Soaking of the analogues for variable time periods provides evidence for anthranilate located at transient positions during transfer from the outer site to the inner catalytic site. PRPP and Mg2+ binding have been shown to be associated with the rearrangement of two flexible loops, which is required to complete the inner anthranilate binding site. It is proposed that anthranilate first binds to the outer site, providing an unusual mechanism for substrate capture and efficient transfer to the catalytic site following the binding of PRPP. Alternative substrates reveal catalytic cycle and key binding events in the reaction catalysed by anthranilate phosphoribosyltransferase from Mycobacterium tuberculosis.,Cookson TV, Castell A, Bulloch EM, Evans GL, Short FL, Baker EN, Lott JS, Parker EJ Biochem J. 2014 Apr 9. PMID:24712732 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Phosphoribosyltransferase 3D structures

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