Download MendeleyCrystal structure of GyrA intein from Mycobacterium xenopi reveals structural basis of protein splicing.
Klabunde, T., Sharma, S., Telenti, A., Jacobs Jr., W.R., Sacchettini, J.C.(1998) Nat Struct Biol 5: 31-36
- PubMed: 9437427
- DOI: https://doi.org/10.1038/nsb0198-31
- Primary Citation of Related Structures:
1AM2 - PubMed Abstract:
Several genes from prokaryotes and lower eukaryotes have been found to contain an in-frame open reading frame, which encodes for an internal protein (intein). Post-translationally, the internal polypeptide auto-splices and ligates the external sequences to yield a functional external protein (extein) and an intein. Most, but not all inteins, contain, apart from a splicing domain, a separate endonucleolytic domain that enables them to maintain their presence by a homing mechanism. We report here the crystal structure of an intein found in the gyrase A subunit from Mycobacterium xenopi at 2.2 A resolution. The structure contains an unusual beta-fold with the catalytic splice junctions at the ends of two adjacent antiparallel beta-strands. The arrangement of the active site residues Ser 1, Thr 72, His 75, His 197, and Asn 198 is consistent with a four-step mechanism for the cleavage-ligation reaction. Using site-directed mutagenesis, the N-terminal cysteine, proposed as the nucleophile in the first step of the splicing reaction, was changed to a Ser 1 and Ala 0, thus capturing the intein in a pre-spliced state.
Organizational Affiliation:
Department of Biochemistry and Biophysics, Texas A&M University, College Station 77843-2128, USA.
