3c8z

The 1.6 A Crystal Structure of MshC: The Rate Limiting Enzyme in the Mycothiol Biosynthetic Pathway

spinqualitylabelsall models 3c8z, resolution 1.60Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3c8z is a 2 chain structure with sequence from Mycobacterium smegmatis. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: 1PE, 5CA, EPE, SO4, ZN Related: 1u0b, 1li5 Gene: cysS (Mycobacterium smegmatis) Activity: Cysteine--tRNA ligase, with EC number 6.1.1.16 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum Function [MSHC_MYCS2] Catalyzes the ATP-dependent condensation of GlcN-Ins and L-cysteine to form L-Cys-GlcN-Ins. 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 PubMed Mycobacterium smegmatis MshC catalyzes the ATP-dependent condensation of GlcN-Ins and l-cysteine to form l-Cys-GlcN-Ins, the penultimate step in mycothiol biosynthesis. Attempts to crystallize the native, full-length MshC have been unsuccessful. However, incubation of the enzyme with the cysteinyl adenylate analogue, 5'-O-[N-(l-cysteinyl)-sulfamonyl]adenosine (CSA), followed by a 24-h limited trypsin proteolysis yielded an enzyme preparation that readily crystallized. The three-dimensional structure of MshC with CSA bound in the active site was solved and refined to 1.6 A. The refined structure exhibited electron density corresponding to the entire 47 kDa MshC molecule, with the exception of the KMSKS loop (residues 285-297), a loop previously implicated in the formation of the adenylate in related tRNA synthases. The overall tertiary fold of MshC is similar to that of cysteinyl-tRNA synthetase, with a Rossmann fold catalytic domain. The interaction of the thiolate of CSA with a zinc ion at the base of the active site suggests that the metal ion participates in amino acid binding and discrimination. A number of active site residues were observed to interact with the ligand, suggesting a role in substrate binding and catalysis. Analysis utilizing modeling of the proteolyzed loop and GlcN-Ins docking, as well as the examination of sequence conservation in the active site suggests similarities and differences between cysteinyl-tRNA synthetases and MshC in recognition of the substrates for their respective reactions. The 1.6 A crystal structure of Mycobacterium smegmatis MshC: the penultimate enzyme in the mycothiol biosynthetic pathway.,Tremblay LW, Fan F, Vetting MW, Blanchard JS Biochemistry. 2008 Dec 16;47(50):13326-35. PMID:19053270 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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