Modular organization of inteins and C-terminal autocatalytic domains - PubMed (original) (raw)

Modular organization of inteins and C-terminal autocatalytic domains

S Pietrokovski. Protein Sci. 1998 Jan.

Abstract

Analysis of the conserved sequence features of inteins (protein "introns") reveals that they are composed of three distinct modular domains. The N-terminal (N) and C-terminal (C) domains are predicted to perform different parts of the autocatalytic protein splicing reaction. An optional endonuclease domain (EN) is shown to correspond to different types of homing endonucleases in different inteins. The N domain contains motifs predicted to catalyze the first steps of protein splicing, leading to the cleavage of the intein N terminus from its protein host. Intein N domain motifs are also found in C-terminal autocatalytic domains (CADs) present in hedgehog and other protein families. Specific residues in the N domain of intein and CADs are proposed to form a charge relay system involved in cleaving their N-termini. The intein C domain is apparently unique to inteins and contains motifs that catalyze the final protein splicing steps: ligation of the intein flanks and cleavage of its C terminus to release the free intein and spliced host protein. All intein EN domains known thus far have dodecapeptide (DOD, LAGLI-DADG) type homing endonuclease motifs. This work identifies an EN domain with an HNH homing-endonuclease motif and two new small inteins with no EN domains. One of these small inteins might be inactive or a "pseudo intein." The results suggest a modular architecture for inteins, clarify their origin and relationship to other protein families, and extend recent experimental findings on the functional roles of intein N, C, and EN motifs.

PubMed Disclaimer

Similar articles

Cited by

References

    1. J Mol Biol. 1977 May 25;112(3):535-42 - PubMed
    1. Trends Genet. 1997 Jan;13(1):14-21 - PubMed
    1. J Biol Chem. 1990 Apr 25;265(12):6726-33 - PubMed
    1. Nature. 1992 May 28;357(6376):301-6 - PubMed
    1. Proc Natl Acad Sci U S A. 1992 Jun 15;89(12):5577-81 - PubMed

Publication types

MeSH terms

Substances

LinkOut - more resources