2l8l

Structure of an engineered splicing intein mutant based on Mycobacterium tuberculosis RecA

spinqualitylabelsall models 2l8l Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2l8l is a 1 chain structure with sequence from Mycobacterium tuberculosis. Full experimental information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: Solution NMR Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function RECA_MYCTU Can catalyze the hydrolysis of ATP in the presence of single-stranded DNA, the ATP-dependent uptake of single-stranded DNA by duplex DNA, and the ATP-dependent hybridization of homologous single-stranded DNAs. It interacts with LexA causing its activation and leading to its autocatalytic cleavage.[HAMAP-Rule:MF_00268] PI-MtuI is an endonuclease.[HAMAP-Rule:MF_00268] Publication Abstract from PubMed Protein splicing is a robust multistep posttranslational process catalyzed by inteins. In the Mtu RecA intein, a conserved block-F aspartate (D422) coordinates different steps in protein splicing, but the precise mechanism is unclear. Solution NMR shows that D422 has a strikingly high pK(a) of 6.1, two units above the normal pK(a) of aspartate. The elevated pK(a) of D422 is coupled to the depressed pK(a) of another active-site residue, the block-A cysteine (C1). A C1A mutation lowers the D422 pK(a) to normal, while a D422G mutation increases the C1 pK(a) from 7.5 to 8.5. The pK(a) coupling and NMR structure determination demonstrate that protonated D422 serves as a hydrogen bond donor to stabilize the C1 thiolate and promote the N-S acyl shift, the first step of protein splicing. Additionally, in vivo splicing assays with mutations of D422 to Glu, Cys, and Ser show that the deprotonated aspartate is essential for splicing, most likely by deprotonating and activating the downstream nucleophile in transesterification, the second step of protein splicing. We propose that the sequential protonation and deprotonation of the D422 side chain is the coordination mechanism for the first two steps of protein splicing. pK(a) coupling at the intein active site: implications for the coordination mechanism of protein splicing with a conserved aspartate.,Du Z, Zheng Y, Patterson M, Liu Y, Wang C J Am Chem Soc. 2011 Jul 6;133(26):10275-82. Epub 2011 Jun 9. PMID:21604815 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Endonuclease 3D structures

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