Fungal inteins

An intein is a protein-intervening sequence that catalyzes its own precise excision from a host protein and the ligation of the flanking sequences, the N- and C-exteins, to produce the mature protein. This process, protein splicing, takes place after translation.
We analyzed inteins in the prp8 gene of fungi. The PRP8 protein is one of the largest and most highly conserved nuclear proteins and occupies a central position in the catalytic core of the spliceosome. We demonstrated protein splicing of PRP8 mini-inteins from species of the genus Penicillium and described inteins and introns in the prp8 gene of four Eupenicillium species. A fungal mini-intein could be split artificially and still spliced in trans, and a eukaryotic mini-intein could be reduced further in size.
Because they are compact and splice efficiently inside foreign proteins, fungal PRP8 inteins are attractive for intein-mediated protein engineering, for example protein purification, the addition of fluorescent biosensors and the expression of cytotoxic proteins. We have reviewed the distribution, evolution and applications of fungal inteins.