BIOTECHNOLOGY LETTERS Volume 14 No.8 (august 1992) pp.653-658 Received 24th June EXPRESSION OF HUMAN INTERLEUKIN-2 FROM NATIVE AND SYNTHETIC GENES IN E. COLI" NO CORRELATION BETWEEN MAJOR CODON BIAS AND HIGH LEVEL EXPRESSION HEE-WON LEE 1, JAE-HOON JOO 3, SEONGMAN KANG 3, IN-SUNG SONG 2, JONG-BUM KWON 3 , MOON H. HAN 3, and DOE SUN NA 1. Department of Biochemistry 1, Asan Institute for Life Sciences2, College of Medicine, University of Ulsan, 388-1 Pungnap-dong, Songpa-gu, Seoul 138-040, and Genetic Engineering Institute, Korea Institute of Science and Technology3, San-1 Uheon-dong, Yuseong-gu, Daejun 305-333, Korea SUMMARY Expression of human IL-2 from the cDNA and synthetic gene was compared using the E. coli expression system. Expression plasmids containing the cDNA or synthetic gene in which the only difference was the coding sequences were constructed. Expression of IL-2 from the cDNA and synthetic gene were estimated to be as high as 18% and 14%, respectively. No correlation was found between the major codon bias and high level expression of IL-2 in this system. INTRODUCTION The choice of codons is not random and the preferred use of individual codons varies from organism to organism(Andersson and Kurland, 1990 and references therein). The biased use of codons from random choice occurs with highly explessed genes. In E. coil and yeast there is a strong correlation between protein expression level and degree of codon bias, and a set of 'high' and 'low' codons have been deduced(Bennetzen and Hall, 1982; Gouy and Gautier, 1982; Grosjean and Fiers, 1982; Sharp et al., 1986; Buhner, 1987). It has been suggested that heterologous genes with 'low' codon usage might not be efficiently expressed(Sharp and Li, 1986; Pederson, 1984; Sorensen et al., 1989; Makoff et al., 1989; Ernst and Kawashima, 1988; Williams et al., 1988). Other reports indicated that heterologous genes with 'low' codons are highly expressed in E. coli (Young et al., 1983; Seeburg et al., 1983; Devos et al., 1983; Simons et al., 1984). Interleukin-2(IL-2) is a major lymphokine for T lymphocytes with numerous biological activities (Morgan, 1976; Smith, 1984). Recombinant human IL-2 has been produced in E. coli from the cDNA at a high level despite that human IL-2 cDNA has 'low' codon bias (Devos et all, 1983). On the other hand, other reports indicated 653