Abstract
The yeast nuclear gene CBP2 was previously proposed to code for a protein necessary for processing of the terminal intron in the cytochrome b pre-mRNA (McGraw, P., and Tzagoloff, A. (1983) J. Biol. Chem. 258, 9459-9468). In the present study we describe a mitochondrial mutation capable of suppressing the respiratory deficiency of cbp2 mutants. The mitochondrial suppressor mutation has been shown to be the result of a precise excision of the last intervening sequence from the cytochrome b gene. Strains with the altered mitochondrial DNA have normal levels of mature cytochrome b mRNA and of cytochrome b and exhibit wild type growth on glycerol. These results confirm that CBP2 codes for a protein specifically required for splicing of the cytochrome b intron and further suggest that absence of the intervening sequence does not noticeably affect the expression of respiratory function in mitochondria.
Highlights
Respiratorycompetentrevertants were picked over a three week period with the majority of revertants appearing during the second and thirdweek
The yeast nuclear gene CBP2 was previously proposed to code for a protein necessary for processing of the terminal intron in the cytochrome b pre-mRNA (McGraw,P., and Tzagoloff, A. (1983) J
In the present study we describe a mitochondrialmutation capable of suppressing the respiratory deficiency of cbp2 mutants
Summary
AE26p0 E26p0 D273-10B/Alpo M10-150/Al M9-94/A1 M9-3/A1 M17-162 M7-40/A1 a, p+,adel, cbp. Cbpa2,-9p+, met, a, p+,met a, p+,ade2h-i1s3, -11,l1eu52, -3,1R1.2, trpl-1, urd-1, canl-100 a, po, knrl-1, leu a, PO, karl-1, ade, lys. Lys ade2,a, p+, a, p+,met, cbp, cobl-20 a, p+,met, cobl-20 a, p+, m t 6 , cbp a,p+, met a, p+,ade, his, trTphl-i1s urd-1, canl-100, CBP2::LEM a, po,adel, cbp. Strains in opposite mating types were mixed on solid YPD medium (2% glucose, 2% peptone, 1%yeast extract, 2% agar), incubated at 30 "C overnight and replicated to minimal glucose medium to select for diploid progeny. The diploid cells were replicated on YEPG medium (3% glycerol, 2% ethanol, 2% peptone, 1%yeast extract, 2% agar) and growth was scored after two days of incubation at 30 "C. Minus signs indicate lack of growth of the diploid cells on YEPG after several days. AE26/R29Bpo aE26/R29B aE26/R29Bp- [1] aE26/R29Bp- [2] aE26/R29Bp- [3] aE26/R29Bp- [4]
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