TY - JOUR
T1 - Partial suppression of an ochre mutation in Saccharomyces cerevisiae by multicopy plasmids containing a normal yeast tRNAGln gene
AU - Pure, Glenn A.
AU - Robinson, Gordon W.
AU - Naumovski, Louie
AU - Friedberg, Errol C.
N1 - Funding Information:
We thank b-s R. Baker and B. Hall for the in vitro transcription studies and for stimulating discussions: l)r R. Snow for communicating unpublished results to us; and David A. Clayton, Roger Schultz, Bill Weiss and Elizabeth Yang for their critical comments on the manuscript. We are particularly grateful to Dr J. Carbon for providing us with plasmid pGT20, to Dr 6. Roeder for plasmid pR169 and to Dr S. Karlin for the computer analysis of the DXA sequences. This work was supported by research grant CA-12428 from the United States Public Healt,h Service. G.A.P. was a Fogartv Fellow supported by United States Public Health Se&ice grant TWO 3212. LX. is a member of the Stanford [Tniversity Medical Scientist Training Program supported b? training grant GM-07365 from the United States Public Health Service, and G.W.R. is supported by postdoctoral national service award CA-07437 from the ITnited States Public Health Service.
PY - 1985/5/5
Y1 - 1985/5/5
N2 - We screened a yeast genomic library for recombinant DNA plasmids that complemented the ultraviolet (u.v.) sensitivity of a strain of Saccharomyces cerevisiae designated rad4-3 that is defective in excision repair of DNA. A multicopy plasmid (pNF4000) with a 9.4 × 103 base-pair yeast DNA insert partially complemented the u.v. sensitivity of rad4-3, but not of two other rad4 allelic mutants (rad4-2 and rad4-4), or of other u.v.-sensitive rad mutants. The yeast insert was analyzed by restriction mapping, DNA-DNA hybridization, DNA-tRNA hybridization and DNA sequencing. This analysis revealed the presence of a normal tRNAGln gene, a yeast sigma element situated 5′ to the transfer RNA gene, a Ty element and a solo delta element. Deletion analysis of pNF4000 showed that the tRNAGln gene is required for partial complementation of the u.v. sensitivity of rad4-3. Furthermore, a multicopy plasmid containing a tRNAGln gene derived from a different region of the yeast genome also partially complemented the u.v. sensitivity of rad4-3. The rad4-3 mutation is suppressed following transformation with a plasmid containing the known ochre suppressor SUP11-o, indicating that it is an ochre mutation. We therefore conclude that when expressed in sufficient quantity, normal tRNAGln (which usually decodes the sense codon CAA) can weakly suppress the nonsense ochre codon UAA, and suggest that this represents an example of wobble occurring at the first rather than at the third position of the codon.
AB - We screened a yeast genomic library for recombinant DNA plasmids that complemented the ultraviolet (u.v.) sensitivity of a strain of Saccharomyces cerevisiae designated rad4-3 that is defective in excision repair of DNA. A multicopy plasmid (pNF4000) with a 9.4 × 103 base-pair yeast DNA insert partially complemented the u.v. sensitivity of rad4-3, but not of two other rad4 allelic mutants (rad4-2 and rad4-4), or of other u.v.-sensitive rad mutants. The yeast insert was analyzed by restriction mapping, DNA-DNA hybridization, DNA-tRNA hybridization and DNA sequencing. This analysis revealed the presence of a normal tRNAGln gene, a yeast sigma element situated 5′ to the transfer RNA gene, a Ty element and a solo delta element. Deletion analysis of pNF4000 showed that the tRNAGln gene is required for partial complementation of the u.v. sensitivity of rad4-3. Furthermore, a multicopy plasmid containing a tRNAGln gene derived from a different region of the yeast genome also partially complemented the u.v. sensitivity of rad4-3. The rad4-3 mutation is suppressed following transformation with a plasmid containing the known ochre suppressor SUP11-o, indicating that it is an ochre mutation. We therefore conclude that when expressed in sufficient quantity, normal tRNAGln (which usually decodes the sense codon CAA) can weakly suppress the nonsense ochre codon UAA, and suggest that this represents an example of wobble occurring at the first rather than at the third position of the codon.
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U2 - 10.1016/0022-2836(85)90278-5
DO - 10.1016/0022-2836(85)90278-5
M3 - Article
C2 - 2989539
AN - SCOPUS:0022410223
SN - 0022-2836
VL - 183
SP - 31
EP - 42
JO - Journal of Molecular Biology
JF - Journal of Molecular Biology
IS - 1
ER -