Nucleic Acids Research, Vol. 19, No. 1 179

New genes for tRNA tRNALeu, and tRNA from Saccharomyces cerevisiae ,

R.Stucka, P.Nelbock, R.Krieg, C.Schwarzlose and H.Feldmann Institut fOr Physiologische Chemie, Physikalische Biochemie und Zellbiologie der Universitat MOnchen, Goethestrasse 33, D 8000 MOnchen 2, FRG Submitted November 20, 1990 During chromosomal waLking (R.Stucka et al., unpublished), we encountered several new tRNA genes on chromosome II from S. cerevisiae (strain C836). With these, the total number of tRNA genes located on chromosome II of this strain amounts to eight (R.Stucka et al., unpublished). A tRNAPhe(AAG) gene is located on the left arm of chromosome II and, as inferred from its neighbouring sequences, some 560 bp upstream of the ATPJ gene (1). In its structural part, the tRNAPhc gene is identical to the major tDNAPhe (2) but differs from it in two positions of its intron sequence as is marked in the cloverleaf figure. The tRNALeU gene, located at the left end of chromosome II in the vicinity of a Ty2 element, has the anticodon TAA and thus represents a novel isoacceptor for leucinc in yeast. The sequence of this tDNAIxU is 63 % homologous to yeast tDNAIxU3 (3) but does not possess an intron; about the same degree of homology is found with the major yeast tDNASer(UcA) (4). The putative tRNAIuu(UAA) seems to be designed to read the UUA leucine codon. Whether tRNAIxu(uAA) is also capable of reading codon UUG cannot be inferred from the DNA sequence since modification of the uracil base at the wobble position greatly influences the specificity of base pairing (5). Codon usage in yeast (6) suggests that the prevalent leucine codon UUG is read by the major tRNALeu3 which has the anticodon 5mCAA (7), whereas the less abundant UUA leucine codon might be specifically read by a tRNAI,eU with the anticodon UAA. Near the centromere of chromosome II, we found a tRNA gene that by its colinearity with one of the reported yeast isoacceptors for threonine (tRNAThrla) (8) could be identified as the first tRNAThr gene in yeast. tRNAThrla has the anticodon IGU and therefore should allow base pairing with three out of the four threonine codons. By sequence comparisons, we could identify another tRNAThr gene: positions 169 through 240 in the upstream region of SE6, located on the left arm of chromosome XI (9), can be folded into a cloverleaf structure representing a second tDNA"hr which is 73% homologous to the first one. The sequence CGT in the anticodon position suggests that the second tRNAThr is a threonine isoacceptor serving the codon ACG.

EMBL accession nos X56504 - X56506 (incl.) 4. Olson,M.V., Page,G.S., Sentenac,A., Piper,P.W., Worthington,M., Weiss,R.B. and Hall,B.D. (1981) Nature 291, 464-469. 5. Heckman,J.E., Sarnoff,J., Alzner-DeWeerd,B., Yin,S. and RajBhandary,U.L. (1980) Proc. Natl. Acad. Sci. USA 77, 3159-3163. 6. Sharp,P.M., Tuohy,T.M.F. and Mosurski,K.R. (1986) Nucl. Acids Res. 14, 5125-5143. 7. Chang,S.H., Kuo,S., Hawkins,E. and Miller,N.R. (1973) Biochem Biophys. Res. Comm. 51, 951-955. 8. Weissenbach,J., Kiraly,I. and Dirheimer,G. (1977) Biochimie 59, 381-391. 9. McGrath,J.P. and Varshavsky,A. (1989) Nature 340, 400-404.

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1. Takeda,M., Chen,W.-J., Saltzgaber,J. and Douglas,M.G. (1986) J. Biol. Chem. 261, 15126-15133. 2. Valenzuela,P., Venegas,A., Weinberg,F., Bishop,R. and Rutter,W.J. (1978) Proc. Natl. Acad. Sci. USA 75, 190-194. 3. Mattoccia,E., Baldi,M.L., Pande,G., Ogden,R. and Tocchini-Valcntini,G.P. (1983) Cell 32, 67-76.

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New genes for tRNA(Phe), tRNA(Leu), and tRNA(Thr) from Saccharomyces cerevisiae.

Nucleic Acids Research, Vol. 19, No. 1 179 New genes for tRNA tRNALeu, and tRNA from Saccharomyces cerevisiae , R.Stucka, P.Nelbock, R.Krieg, C.Schw...
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