2i6y
From Proteopedia
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| , resolution 2.500Å | |||||||
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| Gene: | mbtI, MT2454, Rv2386c (Mycobacterium tuberculosis) | ||||||
| Activity: | Anthranilate synthase, with EC number 4.1.3.27 | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
Structure and Mechanism of Mycobacterium tuberculosis Salicylate Synthase, MbtI
Overview
MbtI (rv2386c) from Mycobacterium tuberculosis catalyzes the initial transformation in mycobactin biosynthesis by converting chorismate to salicylate. We report here the structure of MbtI at 2.5 A resolution and demonstrate that isochorismate is a kinetically competent intermediate in the synthesis of salicylate from chorismate. At pH values below 7.5 isochorismate is the dominant product while above this pH value the enzyme converts chorismate to salicylate without the accumulation of isochorismate in solution. The salicylate and isochorismate synthase activities of MbtI are Mg2+-dependent, and in the absence of Mg2+ MbtI has a promiscuous chorismate mutase activity similar to that of the isochorismate pyruvate lyase, PchB, from Pseudomonas aeruginosa. MbtI is part of a larger family of chorismate-binding enzymes descended from a common ancestor (the MST family), that includes the isochorismate synthases and anthranilate synthases. The lack of active site residues unique to pyruvate eliminating members of this family, combined with the observed chorismate mutase activity, suggests that MbtI may exploit a sigmatropic pyruvate elimination mechanism similar to that proposed for PchB. Using a combination of structural, kinetic, and sequence based studies we propose a mechanism for MbtI applicable to all members of the MST enzyme family.
About this Structure
2I6Y is a Single protein structure of sequence from Mycobacterium tuberculosis. Full crystallographic information is available from OCA.
Reference
Structure and mechanism of MbtI, the salicylate synthase from Mycobacterium tuberculosis., Zwahlen J, Kolappan S, Zhou R, Kisker C, Tonge PJ, Biochemistry. 2007 Jan 30;46(4):954-64. PMID:17240979
Page seeded by OCA on Thu Mar 20 17:26:11 2008
