Intragenic suppressors that restore the splicing and homing activities of the protein encoded by the second intron of the Saccharomyces capensis cyt b gene
K. Jamoussi et J. Lazowska, Intragenic suppressors that restore the splicing and homing activities of the protein encoded by the second intron of the Saccharomyces capensis cyt b gene, CURR GENET, 38(5), 2000, pp. 276-282
The second (bi2) intron of the mitochondrial cyt b gene from Saccharomyces
capensis encodes a bifunctional protein which acts both as a maturase, prom
oting intron splicing, and as a homing-endonuclease, I-ScaI, promoting intr
on mobility. In this work we isolated and characterized revertants from a r
espiratory-deficient mutant in which both functions of the protein have bee
n lost. Intragenic revertants resulted mainly from monosubstitutions in the
mutated codon and in one case from a distant second site mutation. All nov
el variants of the S. capensis bi2 intron-encoded protein are competent for
the maturase activity but only two of them can partially complement the ho
ming function.