Structural highlights
Publication Abstract from PubMedThe first crystal trans-structure of a naturally occurring split intein has been determined for the Npu DnaE split intein. Guided by this structure, the residues NArg50 and CSer35, well conserved in DnaE split inteins, are identified to be critical in the trans-splicing of Npu DnaE split intein. An in vitro splicing assay demonstrates that NArg50 and CSer35 play synergistic roles in modulating its intein activity. The C-terminal asparagine CAsn36 exhibits two orientations of its side-chain and interacts with both NArg50 and CSer35 through H-bonding. These interactions likely facilitate cyclization of Asn in the course of protein splicing. The mutation of either residue reduces intein activity, and correlates with the low activity of the Ssp DnaE split intein. On the other hand, NArg50 also forms a H-bond with the highly conserved F-block aspartate CAsp17, thus influencing the N-S acyl shift during N-terminal cleavage. Sequence alignments show that residues NArg50 and CSer35 are rather conserved in those split inteins that lack a penultimate histidine residue. The conserved non-catalytic residues of split inteins modulate the efficiency of protein trans-splicing by H-bond interactions with the catalytic residues at the splice junction. Conserved Residues that Modulate Protein trans-Splicing of Npu DnaE Split Intein.,Wu Q, Gao ZQ, Wei Y, Ma G, Zheng Y, Dong YH, Liu Y Biochem J. 2014 Apr 23. PMID:24758175[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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