Molecular characterization and analysis of the biosynthetic gene cluster for the antitumor antibiotic mitomycin C from Streptomyces lavendulae NRRL 2564

Chemistry and Biology

Volumn 6, Issue 4, 1999, Pages 251-263

  Yingqing, Mao ^a   Varoglu, Mustafa ^a   Sherman, David H ^a  

^a UNIVERSITY OF MINNESOTA   (United States)

Author keywords

Antibiotic biosynthesis; Antibiotic resistance; Gene disruption; Mitosane; Shikimate pathway

Indexed keywords

3 AMINO 5 HYDROXYBENZOIC ACID; ALKYLATING AGENT; ANTINEOPLASTIC ACTIVITY; BACTERIAL MUTANT; BIOCHEMICAL PATHWAY; BIOSYNTHESIS; CARBAMOYL PHOSPHATE; CARRIER PROTEIN; CELL NUCLEUS; CLONED GENE; DRUG BINDING SITE; GENE CLUSTER; GENETIC LINKAGE; GLUCOSAMINE; METHIONINE; MITOMYCIN C; REGULATOR GENE; TARGETED MUTAGENESIS;

STREPTOMYCES LAVENDULAE;

EID: 0033117369     PISSN: 10745521     EISSN: None     Source Type: Journal    
DOI: 10.1016/S1074-5521(99)80040-4     Document Type: Article

References (106)

1. Hata, T., et al. & Hoshi, T. (1956). Mitomycin, a new antibiotic from Streptomyces. J. Antibiot. Ser. A 9, 141-146.
2. Verweij, J. (1997). Mitomycins. Cancer Chemother. Biol. Response Modif. 17, 46-58.
3. Boyer, M.J. (1997). Bioreductive agents: A clinical update. Oncol. Res. 9, 391-395.
4. Cummings, J., Spanswick, V.J., Tomasz, M. & Smyth, J.F. (1998). Enzymology of mitomycin C metabolic activation in tumour tissue - Implications for enzyme-directed bioreductive drug development. Biochem. Pharmacol. 56, 405-414.
5. Tomasz, M. & Palom, Y. (1997). The mitomycin bioreductive antitumor agents: Cross-linking and alkylation of DNA as the molecular basis of their activity. Pharmacol. Therap. 76, 73-87.
6. Spanswick, V.J., Cummings, J. & Smyth, J.F. (1998). Current issues in the enzymology of mitomycin C metabolic activation. Gen. Pharmacol. 31, 539-544.
7. Henderson, I.C. (1993). Recent advances in the usage of mitomycin. Proceedings of a symposium. Hawaii, March 21-24, 1991. Oncology 1, 1-83.
8. Pan, S.S. & Iracki, T. (1988). Metabolites and DNA adduct formation from flavoenzyme-activated porfiromycin. Mol. Pharmacol. 34, 223-228.
9. Wakaki, K., et al. & Fujimoto, Y. (1958). Isolation of new fractions of antitumor mitomycins. Antibiot. Chemother. 8, 228-240.
10. Paz, M.M. & Hopkins, P.B. (1997). DNA-DNA interstrand cross-linking by FR66979 - Intermediates in the activation cascade. J. Am. Chem. Soc. 119, 5999-6005.
11. Williams, R.M., Rajski, S.R. & Rollins, S.B. (1997). FR900482, a close cousin of mitomycin C that exploits mitosene-based DNA cross-linking. Chem. Biol. 4, 127-137.
12. Hirai, O., et al., & Mine, Y. (1994). Microbial mutagenicity and in vitro chromosome aberration induction by FK973, a new antitumor agent. Mutation Res. 324, 43-50.
13. Naoe, Y., et al., & Shimomura, K. (1998). FK317 - A novel substituted dihydrobenzoxazine with potent antitumor activity which does not induce vascular leak syndrome. Cancer Chemother. Pharmacol. 42, 31-36.
14. Smitskamp-Wilms, E., Hendriks, H.R. & Peters, G.J. (1996). Development, pharmacology, role of dt-diaphorase and prospects of the indoloquinone EO9. Gen. Pharmacol. 27, 421-429.
15. Evans, J.W., Yudoh, K., Delahoussaye, Y.M. & Brown, J.M. (1998). Tirapazamine is metabolized to its DNA-damaging radical by intranuclear enzymes. Cancer Res. 58, 2098-2101.
16. Kasai, M. & Arai, H. (1995). Novel mitomycin derivatives. Exp. Opin. Ther. Patents 5, 757-770.
17. Shikano, M., et al., & Uehara, Y. (1998). 1a-docosahexaenoyl mitomycin C: A novel inhibitor of protein tyrosine kinase. Biochem. Biophys. Res. Commun. 248, 858-863.
18. Becker, A.M., Herlt, A.J., Hilton, G.L, Kibby, J.J. & Rickards, R.W. (1983). 3-amino-5-hydroxybenzoic acid in antibiotic biosynthesis. VI. Directed biosynthesis studies with ansamycin antibiotics. J. Antibiot. 36, 1323-1328.
19. Kibby, J.J. & Rickards, R.W. (1981). The identification of 3-amino-5-hydroxybenzoic acid as a new natural aromatic amino acid. J. Antibiot. 34, 605-607.
20. Anderson, M.G., Kibby, J.J., Rickards, R.W. & Rothschild, J.M. (1980). Biosynthesis of the mitomycin antibiotics from 3-amino-5-hydroxybenzoic acid. J. Chem. Soc. Chem. Comm. 1277-1278.
21. Hornemann, U. (1981). Biosynthesis of the mitomycins. In Biosynthesis. (Corcoran, J. W., ed.), pp. 295-312, The Chemical Society, London.
22. Bezanson, G.S. & Vining, L.C. (1971). Studies on the biosynthesis of mitomycin C by Streptomyces verticillatus. Can. J. Biochem. 49, 911-918.
23. 15N) citrulline in mitomycin biosynthesis by Streptomyces verticillatus. J. Antibiot. 28, 841-843.
24. Hornemann, U., Kehrer, J.P., Nunez, C.S. & Ranieri, R.L. (1974). D-glucosamine and L-citrulline, precursors in mitomycin biosynthesis by Streptomyces verticillatus. J. Am. Chem. Soc. 96, 320-322.
25. Floss, H.G. (1997). Natural products derived from unusual variants of the shikimate pathway. Nat. Prod. Rep. 14, 433-452.
26. Tomasz, M. (1995). Mitomycin C: Small, fast and deadly (but very selective). Chem. Biol. 2, 575-579.
27. August, P.R., Flickinger, M.C. & Sherman, D.H. (1994). Cloning and analysis of a locus (mcr) involved in mitomycin C resistance in Streptomyces lavendulae. J. Bacteriol. 176, 4448-4454.
28. Sheldon, P.J., Johnson, D.A., August, P.J., Liu, H.-w. & Sherman, D.H. (1997). Characterization of a mitomycin-binding drug resistance mechanism from the producing organism, Streptomyces lavendulae. J. Bacteriol. 179, 1796-1804.
29. Mao, Y.Q., Varoglu, M. & Sherman, D.H. (1999). Genetic localization and molecular characterization of two key genes (mitAB) required for biosynthesis of the antitumor antibiotic mitomycin C. J. Bacteriol. 181, 2199-2208.
30. 7N units in rifamycin and related antibiotics. J. Biol. Chem. 273, 6030-6040.
31. August, P.R., et al., & Floss, H.G. (1998). Biosynthesis of the ansamycin antibiotic rifamycin: Deductions from the molecular analysis of the rif biosynthetic gene cluster of Amycolatopsis mediterranei S699. Chem. Biol. 5, 69-79.
32. Rodriguez, A.M., Olano, C., Mendez, C., Hutchinson, C.R. & Salas, J.A. (1995). A cytochrome P450-like gene possibly involved in oleandomycin biosynthesis by Streptomyces antibioticus. FEMS Microbiol. Lett. 127, 117-120.
33. Schwecke, T., et al., & Leadlay, P.F. (1995). The biosynthetic gene cluster for the polyketide immunosuppressant rapamycin. Proc. Natl. Acad. Sci. USA 92, 7839-7843.
34. Horii, M., Ishizaki, T., Paik, S.Y., Manome, T. & Murooka, Y. (1990). An operon containing the genes for cholesterol oxidase and a cytochrome P-450-like protein from a Streptomyces sp. J. Bacteriol. 172, 3644-3653.
35. Omer, C.A., et al. & O'Keefe, D.P. (1990). Genes for two herbicide-inducible cytochromes P-450 from Streptomyces griseolus. J. Bacteriol. 172, 3335-3345.
36. Fernandez-Moreno, M.A., Caballero, J.L., Hopwood, D.A. & Malpartida, F. (1991). The acf cluster contains regulatory and antibiotic export genes, direct targets for translational control by the bldA tRNA gene of Streptomyces. Cell 66, 769-780.
37. Perez-Llarena, F.J., Liras, P., Rodriguez-Garcia, A. & Martin, J.F. (1997). A regulatory gene (ccaR) required for cephamycin and clavulanic acid production in Streptomyces clavuligerus: Amplification results in overproduction of both beta-lactam compounds. J. Bacteriol. 179, 2053-2059.
38. Takano, E., Gramajo, H.C., Strauch, E., Andres, N., White, J. & Bibb, M.J. (1992). Transcriptional regulation of the redD transcriptional activator gene accounts for growth-phase-dependent production of the antibiotic undecylprodigiosin in Streptomyces coelicolor A3(2). Mol. Microbiol. 6, 2797-2804.
39. Tang, L., Grimm, A., Zhang, Y.X. & Hutchinson, C.R. (1996). Purification and characterization of the DNA-binding protein Dnrl, a transcriptional factor of daunorubicin biosynthesis in Streptomyces peucetius. Mol. Microbiol 22, 801-813.
40. Wietzorrek, A. & Bibb, M. (1997). A novel family of proteins that regulates antibiotic production in streptomycetes appears to contain an OmpR-like DNA-binding fold. Mol. Microbiol 25, 1181-1184.
41. Ohno, T., et al. & Watanabe, T. (1996). A modular family 19 chitinase found in the prokaryotic organism Streptomyces griseus HUT 6037. J. Bacteriol. 178, 5065-5070.
42. Seno, E.T. & Baltz, R.H. (1989). Structural Organization and Regulation of Antibiotic Biosynthesis and Resistance Genes in Actinomycetes. CRC Press, Boca Raton, FL.
43. Sheldon, P.J., Mao, Y.Q., He, M. & Sherman, D.H. (1999). Mitomycin resistance in Streptomyces lavendulae includes a novel drug-binding protein-dependent export system. J. Bacteriol., in press.
44. Johnson, D.A., August, P.R., Shackleton, C., Liu, H.-w. & Sherman, D.H. (1997). Microbial resistance to mitomycins involves a redox relay mechanism. J. Am. Chem. Soc. 119, 2576-2577.
45. Makino, K., Shinagawa, H., Amemura, M. & Nakata, A. (1986). Nucleotide sequence of the phoB gene, the positive regulatory gene for the phosphate regulon of Escherichia coli K-12. J. Mol. Biol. 190, 37-44.
46. Dean, C.R., Neshat, S. & Poole, K. (1996). PfeR, an enterobactin-responsive activator of ferric enterobactin receptor gene expression in Pseudomonas aeruginosa. J. Bacteriol. 178, 5361 -5369.
47. Lee, P.J. & Stock, A.M. (1996). Characterization of the genes and proteins of a two-component system from the hyperthermophilic bacterium Thermotoga maritima. J. Bacteriol. 178, 5579-5585.
48. Mizuno, T. & Tanaka, I. (1997). Structure of the DNA-binding domain of the OmpR family of response regulators. Mol. Microbiol. 24, 665-667.
49. Lomovskaya, O., Lewis, K. & Matin, A. (1995). EmrR is a negative regulator of the Escherichia coli multidrug resistance pump EmrAB. J. Bacteriol. 177, 2328-2334.
50. Praillet, T., Nasser, W., Robert-Baudouy, J. & Reverchon, S. (1996). Purification and functional characterization of PecS, a regulator of virulence-factor synthesis in Erwinia chrysanthemi. Mol. Microbiol. 20, 391-402.
51. 7N units in ansamycin antibiotics. J. Am. Chem. Soc. 118, 7486-7491.
52. Dewick, P.M. (1998). The biosynthesis of shikimate metabolites. Nat. Prod. Rep. 15, 17-58.
53. Bult, C.J., et al., & Venter, J.C. (1996). Complete genome sequence of the methanogenic archaeon, Methanococcus jannaschii. Science 273, 1058-1073.
54. Cole, S.T., et al., &. Barrell, B.G. (1998). Deciphering the biology of Mycobacterium tuberculosis from the complete genome sequence. Nature 393, 537-544.
55. White, P.J., Young, J., Hunter, I.S., Nimmo, H.G. & Coggins, J.R. (1990). The purification and characterization of 3-dehydroquinase from Streptomyces coelicolor. Biochem. J. 265, 735-738.
56. Schaferjohann, J., Yoo, J.G., Kusian, B. & Bowien, B. (1993). The cbb opérons of the facultative chemoautotroph Alcaligenes eutrophus encode phosphoglycolate phosphatase. J. Bacteriol. 175, 7329-7340.
57. Angell S., Schwarz E., & Bibb, M.J. (1992). The glucose kinase gene of Streptomyces coelicolor A3(2): Its nucleotide sequence, transcriptional analysis and role in glucose repression. Mol. Microbiol. 6, 2833-2844.
58. Spath, C., Kraus, A. & Hillen, W. (1997). Contribution of glucose kinase to glucose repression of xylose utilization in Bacillus megaterium. J. Bacteriol. 179, 7603-7605.
59. Yamazaki, M., Thorne, L., Mikolajczak, M., Armentrout, R.W. & Pollock, T.J. (1996). Linkage of genes essential for synthesis of a polysaccharide capsule in Sphingomonas strain S88. J. Bacteriol. 178, 2676-2687.
60. Gibson, J., Dispensa, M., Fogg, G.C., Evans, D.T. & Harwood, C.S. (1994). 4-hydroxybenzoate-coenzyme A ligase from Rhodopseudomonas palustris: Purification, gene sequence, and role in anaerobic degradation. J. Bacteriol. 176, 634-641.
61. 2) biosynthesis: Overexpression, purification, and properties of 0-succinylbenzoyl-coenzyme A synthetase from Escherichia coli. J. Bacteriol. 178, 6778-6781.
62. Dittrich, H. & Kutchan, T.M. (1991). Molecular cloning, expression, and induction of berberine bridge enzyme, an enzyme essential to the formation of benzophenanthridine alkaloids in the response of plants to pathogenic attack. Proc. Natl Acad. Sci. USA 88, 9969-9973.
63. Kagan, RM & Clarke, S. (1994). Widespread occurrence of three sequence motifs in diverse S-adenosylmethionine-dependent methyltransferases suggests a common structure for these enzymes. Arch. Biochem. Biophy. 310, 417-427.
64. Shi, J., Gonzales, R.A. & Bhattacharyya, M.K. (1996). Identification and characterization of an S-adenosyl-L-methionine: Δ24-sterol-C-methyltransferase cDNA from soybean. J. Biol. Chem. 271, 9384-9389.
65. Lacalle, R.A., Ruiz, D. & Jimenez, A. (1991). Molecular analysis of the dmpM gene encoding an O-demethyl puromycin O-methyltransferase from Streptomyces alboniger. Gene 109, 55-61.
66. Madduri, K., Torti, F., Colombo, A.L & Hutchinson, C.R. (1993). Cloning and sequencing of a gene encoding carminomycin 4-O-methyltransferase from Streptomyces peucetius and its expression in Escherichia coli. J. Bacteriol. 175, 3900-3904.
67. Hidaka, T., Goda, M., Kuzuyama, T., Takei, N., Hidaka, M. & Seto, H. (1995). Cloning and nucleotide sequence of fosfomycin biosynthetic genes of Streptomyces wedmorensis. Mol. Gen. Genet. 249, 274-280.
68. Hidaka, T., Hidaka, M., Kuzuyama, T. & Seto, H. (1995). Sequence of a P-methyltransferase-encoding gene isolated from a bialaphos-producing Streptomyces hygroscopicus. Gene 158, 149-150.
69. Kuzuyama, T., Seki, T., Dairi, T., Hidaka, T. & Seto, H. (1995). Nucleotide sequence of fortimicin KL1 methyltransferase gene isolated from Micromonospora olivasterospora, and comparison of its deduced amino-acid sequence with those of methyltransferases involved in the biosynthesis of bialaphos and fosfomycin. J. Antibiot. 48, 1191-1193.
70. Deppenmeier, U., Muller, V. & Gottschalk, G. (1996). Pathways of energy conservation in methanogenic archaea. Arch. Microbiol. 165, 149-163.
71. 2 Chapman and Hall, New York, NY.
72. 10-methylenetetrahydromethanopterin reductase-encoding genes from Methanobacterium thermoautotrophicum ΔH and Methanopyrus kandleri. J. Bacteriol. 177, 7238-7244.
73. 10-methylenetetrahydromethanopterin reductase (Mer) from Methanobacterium thermoautotrophicum strain Marburg. Cloning, sequencing, transcriptional analysis, and functional expression in Escherichia coli of the mer gene. Bur. J. Biochem. 231, 773-778.
74. 5-methyltetrahydromethanopterin: coenzyme-M methyltransferase from Methanobacterium thermoautotrophicum. Bur. J. Biochem. 217, 115-121.
75. Morbidoni, H.R., de Mendoza, D. & Cronan, J., Jr. (1996). Bacillus subtilis acyl carrier protein is encoded in a cluster of lipid biosynthesis genes. J. Bacteriol. 178, 4794-4800.
76. Platt, M.W., Miller, K.J., Lane, W.S. & Kennedy, E.P. (1990). Isolation and characterization of the constitutive acyl carrier protein from Rhizobium meliloti. J. Bacteriol. 172, 5440-5444.
77. Decker, H., Motamedi, H. & Hutchinson, C.R. (1993). Nucleotide sequences and heterologous expression of tcmG and tcmP, biosynthetic genes for tetracenomycin C in Streptomyces glaucescens. J. Bacteriol. 175, 3876-3886.
78. Jabbouri, S., et al., & Broughton, W.J. (1998). no/O and noel (HsnIII) of Rhizobium sp. NGR234 are involved in 3-O-carbamoylation and 2-O-methylation of Nod factors. J. Biol. Chem. 273, 12047-12055.
79. Luka, S., Sanjuan, J., Carlson, R.W. & Stacey, G. (1993). nolMNO genes of Bradyrhizobium japonicum are co-transcribed with nodYABCSUIJ, and nolO is involved in the synthesis of the lipo-oligosaccharide nodulation signals. J. Biol. Chem. 268, 27053-27059.
80. Jabbouri, S., et al. & Broughton, W.J. (1995). Involvement of nodS in N-methylation and nodU in 6-O-carbamoylation of Rhizobium sp. NGR234 nod factors. J. Biol. Chem. 270, 22968-22973.
81. Coque, J.J., Perez-Llarena, F.J., Enguita, F.J., Fuente, J.L., Martin, J.F. & Liras, P. (1995). Characterization of the cmcH genes of Nocardia lactamdurans and Streptomyces clavuligerus encoding a functional 3′-hydroxymethylcephem O-carbamoyltransferase for cephamycin biosynthesis. Gene 162, 21-27.
82. Blattner, F.R., et al., & Shao, Y. (1997). The complete genome sequence of Escherichia coli K-12. Science 277, 1453-1474.
83. Chater, K.F. & Bruton, C.J. (1985). Resistance, regulatory and production genes for the antibiotic methylenomycin are clustered. EMBO J. 4, 1893-1897.
84. Caballero, J.L., Malpartida, F. & Hopwood, D.A. (1991). Transcriptional organization and regulation of an antibiotic export complex in the producing Streptomyces culture. Mol. Gen. Genet. 228, 372-380.
85. Yang, K., Man, L. & Vining, L.C. (1995). Regulation of jadomycin B production in Streptomyces venezuelae ISP5230: Involvement of a repressor gene, jadR2. J. Bacteriol. 177, 6111-6117.
86. Otten, S.L., Ferguson, J. & Hutchinson, C.R. (1995). Regulation of daunorubicin production in Streptomyces peucetius by the dnrR2 locus. J. Bacteriol. 177, 1216-1224.
87. Guilfoile, P.G. & Hutchinson, C.R. (1992). The Streptomyces glaucescens TcmR protein represses transcription of the divergently oriented fcmR and tcmA genes by binding to an intergenic operator region. J. Bacteriol. 174, 3659-3666.
88. Guilfoile, P.G. & Hutchinson, C.R. (1992). Sequence and transcriptional analysis of the Streptomyces glaucescens tcmAR tetracenomycin C resistance and repressor gene loci. J. Bacteriol, 174, 3651-3658.
89. Grkovic, S., Brown, M.H., Roberts, N.J., Paulsen, I.T. & Skurray, R.A. (1998). QacR is a repressor protein that regulates expression of the Staphylococcus aureus multidrug efflux pump QacA. J. Biol. Chem. 273, 18665-18673.
90. Mazodier, P., Petter, R. & Thompson, C. (1989). Intergeneric conjugation between Escherichia coli and Streptomyces species. J. Bacteriol. 171, 3583-3585.
91. Tuan, J.S., Weber, J.M., Staver, M.J., Leung, J.O., Donadio, S. & Katz, L. (1990). Cloning of the genes involved in erythromycin biosynthesis from Saccharopolyspora erythraea using a novel Actinomycete-Escherichia coli cosmid. Gene 90, 21-29.
92. Bierman, M., Logan, R., O'Brien, K., Seno, E.T., Rao, R.N. & Schoner, B.E. (1992). Plasmid cloning vectors for the conjugal transfer of DNA from Escherichia coli to Streptomyces spp. Gene 116, 43-49.
93. Sambrook, J., Fritsch, E.F. & Maniatis, T. (1989). Molecular Cloning: A Laboratory Manual. (2nd Edn), Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY.
94. Hopwood, D.A., et al., & Schrempf, H.S. (1985). Genetic Manipulation of Streptomyces: A Laboratory Manual. John Innes Institute, Norwich, United Kingdom.
95. Altschul, S.F., Gish, W., Miller, W., Myers, E.W. & Lipman, D.J. (1990). Basic local alignment search tool. J. Mol. Biol. 215, 403-410.
96. Devereux, J., Haeberli, P. & Smithies, O. (1984). A comprehensive set of sequence analysis programs for the VAX. Nucleic Acids Res. 12, 387-395.
97. Denis, F. & Brzezinski, R. (1992). A versatile shuttle cosmid vector for use in Escherichia coli and actinomycetes. Gene 111, 115-118.
98. Baltz, R.H. (1980). Genetic recombination in Streptomyces fradiae by protoplast fusion and cell regeneration. Dev. Ind. Microbiol. 21, 43-54.
99. 12 level to mitomycin synthesis and enzymatic methylation of a demethylated derivative of mitomycin. Eur. J. Appl. Microbiol. 2, 129-145.
100. Summers, R.G., Wendt-Pienkowski, E., Motamedi, H. & Hutchinson, C.R. (1992). Nucleotide sequence of the tcmII-tcmlV region of the tetracenomycin C biosynthetic gene cluster of Streptomyces glaucescens and evidence that the tcmN gene encodes a multifunctional cyclase-dehydratase-O-methyl transferase. J. Bacteriol. 174, 1810-1820.
101. Haydock, S.F., Dowson, J.A., Dhillon, N., Roberts, G.A., Cortes, J. & Leadlay, P.F. (1991 ). Cloning and sequence analysis of genes involved in erythromycin biosynthesis in Saccharopolyspora erythraea: Sequence similarities between EryG and a family of S-adenosylmethionine-dependent methyltransferases. Mol. Gen. Genet. 230, 120-128.
102. Niemi, J. & Mantsala, P. (1995). Nucleotide sequences and expression of genes from Streptomyces purpurascens that cause the production of new anthracyclines in Streptomyces galilaeus. J. Bacteriol. 177, 2942-2945.
103. Dickens, M.L, Ye, J. & Strohl, W.R. (1995). Analysis of clustered genes encoding both early and late steps in daunomycin biosynthesis by Streptomyces sp. strain C5. J. Bacteriol. 177, 536-543.
104. Grebenok, R.J., Galbraith, D.W. & Penna, D.D. (1997). Characterization of Zea mays endosperm C-24 sterol methyltransferase: One of two types of sterol methyltransferases in higher plants. Plant Mol. Biol. 34, 891-896.
105. Bouvier-Nave, P., Husselstein, T., Desprez, T. & Benveniste, P. (1997). Identification of cDNAs encoding sterol methyl-transferases involved in the second methylation step of plant sterol biosynthesis. Eur. J. Biochem. 246, 518-529.
106. Hardwick, K.G. & Pelham, H.R. (1994). SED6 is identical to ERG6, and encodes a putative methyltransferase required for ergosterol synthesis. Yeast 10, 265-269.