Journal of Biological Chemistry
Volume 279, Issue 5, 30 January 2004, Pages 3121-3131
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Protein Synthesis, Post-Translation Modification, and Degradation
Protein Splicing of Inteins with Atypical Glutamine and Aspartate C-terminal Residues*

https://doi.org/10.1074/jbc.M311343200Get rights and content
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Inteins are protein-splicing domains present in many proteins. They self-catalyze their excision from the host protein, ligating their former flanks by a peptide bond. The C-terminal residue of inteins is typically an asparagine (Asn). Cyclization of this residue to succinimide causes the final detachment of inteins from their hosts. We studied protein-splicing activity of two inteins with atypical C-terminal residues. One having a C-terminal glutamine (Gln), isolated from Chilo iridescent virus (CIV), and another unique intein, first reported here, with a C-terminal aspartate, isolated from Carboxydothermus hydrogenoformans (Chy). Protein-splicing activity was examined in the wild-type inteins and in several mutants with N- and C-terminal amino acid substitutions. We demonstrate that both wild-type inteins can protein splice, probably by new variations of the typical protein-splicing mechanism. Substituting the atypical C-terminal residue to the typical Asn retained protein-splicing only in the CIV intein. All diverse C-terminal substitutions in the Chy intein (Asp345 to Asn, Gln, Glu, and Ala) abolished protein-splicing and generated N- and C-terminal cleavage. The observed C-terminal cleavage in the Chy intein ending with Ala cannot be explained by cyclization of this residue. We present and discuss several new models for reactions in the protein-splicing pathway.

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Holds the Ronson and Harris Career Development Chair.

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The on-line version of this article (available at http://www.jbc.org) contains Figs. S1–S3 and Tables S1 and S2.