Discovery and Molecular Engineering of Sugar-containing Natural Product Biosynthetic Pathways in Actinomycetes

  • Oh, Tae-Jin (Institute of Biomolecule Reconstruction (IBR), Department of Pharmaceutical Engineering, SunMoon University) ;
  • Mo, Sang-Joon (Division of Nano Sciences and Department of Chemistry, Ewha University) ;
  • Yoon, Yeo-Joon (Division of Nano Sciences and Department of Chemistry, Ewha University) ;
  • Sohng, Jae-Kyung (Institute of Biomolecule Reconstruction (IBR), Department of Pharmaceutical Engineering, SunMoon University)
  • Published : 2007.12.31

Abstract

Significant progress has recently been made concerning the engineering of deoxysugar biosynthesis. The biosynthetic gene clusters of several deoxysugars from various polyketides and aminoglycosides-producing microorganisms have been cloned and studied. This review introduces the biosynthetic pathways of several deoxysugars and the generation of novel hybrid macrolide antibiotics via the coexpression of deoxysugar biosynthetic gene cassettes and the substrate-flexible glycosyltransferases in a host organism as well as the production of TDP-deoxysugar derivatives via one-pot enzymatic reactions with the identified enzymes. These recent developments in the engineering of deoxysugars biosynthesis may pave the way to create novel secondary metabolites with potential biological activities.

Keywords

References

  1. Aguirrezabalaga, I., C. Olano, N. Allende, L. Rodriguez, A. F. Brana, C. Mendez, and J. A. Salas. 2000. Identification and expression of genes involved in biosynthesis of Loleandrose and its intermediate L-olivose in the oleandomycin producer Streptomyces antibioticus. Antimicrob. Agents Chemother. 44: 1266-1275 https://doi.org/10.1128/AAC.44.5.1266-1275.2000
  2. Baltz, R. H. 2005. Antibiotic discovery from Actinomycetes: Will a renaissance follow the decline and fall? SIM News 55: 186-196
  3. Bannister, B. and B. A. Zapotocky. 1992. Protorubradirin, an antibiotic containing a C-nitroso-sugar fragment, is the true secondary metabolite produced by Streptomyces achromogenes var. rubradiris. J. Antibiotics 45: 1313-1324 https://doi.org/10.7164/antibiotics.45.1313
  4. Bechthold, A., J. K. Sohng, T. M. Smith, X. Chu, and H. G. Floss. 1995. Identification of Streptomyces vialaceoruber Tu22 genes involved in the biosynthesis of granaticin. Mol. Gen. Genet. 248: 610-620 https://doi.org/10.1007/BF02423457
  5. Borisova, S. A., L. Zhao, C. E. MelanconIII, C. L. Kao, and H. W. Liu. 2004. Characterization of the glycosyltransferase activity of DesVII: Analysis of and implications for the biosynthesis of macrolide antibiotics. J. Am. Chem. Soc. 126: 6534-6535 https://doi.org/10.1021/ja049967j
  6. Chen, H., M. G. Thomas, B. K. Hubbard, H. C. Losey, C. T. Walsh, and M. D. Burkart. 2000. Deoxysugars in glycopeptide antibiotics: Enzymatic synthesis of TDP-Lepivancosamine in chloroeremomycin biosynthesis. Proc. Natl. Acad. Sci. USA 97: 11942-11947
  7. Chong, Y. H., J. M. Young, J. Y. Kim, Y. Y. Lee, K. S. Park, J. H. Cho, H. J. Kwon, J. W. Suh, and Y. H. Lim. 2006. S-Adenosyl-L-methionine analogues to enhance the production of actinorhodin. J. Microbiol. Biotechnol. 16: 1154-1157
  8. Chung, Y. S., D. H. Kim, W. M. Seo, H. C. Lee, K. Liou, T. J. Oh, and J. K. Sohng. 2007. Enzymatic synthesis of dTDP-4-amino-4,6-dideoxy-D-glucose using GerB (dTDP- 4-keto-6-deoxy-D-glucose aminotransferase). Carbohydr. Res. 342: 1412-1418 https://doi.org/10.1016/j.carres.2007.04.007
  9. Dax, S. L. 1997. Antibacterial Chemotherapeutic Agents, 1st Ed. Blackie Academic & Professional, London
  10. Demain, A. L. 1999. Pharmaceutically active secondary metabolites of microorganisms. Appl. Microbiol. Biotechnol. 52: 455-463 https://doi.org/10.1007/s002530051546
  11. Doumith, M., R. Legrand, C. Lang, J. A. Salas, and M. C. Raynal. 1999. Interspecies complementation in Saccharopolyspora erythraea: Elucidation of the function of oleP1, oleG1, and oleG2 from the oleandomycin biosynthetic gene cluster of Streptomyces antibioticus and generation of new erythromycin derivatives. Mol. Microbiol. 34: 1039- 1048 https://doi.org/10.1046/j.1365-2958.1999.01666.x
  12. Elchert, B., J. Li, J. Wang, Y. Hui, R. Rai, R. Ptak, P. Ward, J. Y. Takemoto, M. Bensaci, and C. W. Chang. 2004. Application of the synthetic aminosugars for glycodiversification: Synthesis and antimicrobial studies of pyranmycin. J. Org. Chem. 69: 1513-1523 https://doi.org/10.1021/jo035290r
  13. Fu, X., C. Albermann, C. Zhang, and J. S. Thorson. 2005. Diversifying vancomycin via chemoenzymatic strategies. Org. Lett. 7: 1513-1515 https://doi.org/10.1021/ol0501626
  14. Graninger, M., B. Nidetzky, D. E. Heinrichs, C. Whitfield, and P. Messner. 1999. Characterization of dTDP-4- dehydrorhamnose 3,5-epimerase and dTDP-4-dehydrorhamnose reductase, required for dTDP-L-rhamnose biosynthesis in Salmonella enterica serovar Typhimurium LT2. J. Biol. Chem. 274: 25069-25077 https://doi.org/10.1074/jbc.274.35.25069
  15. Han, J. M., S. M. Kim, H. J. Lee, and J. C. Yoo. 2007. Cloning and expression of glucose-1-phosphate thymidylyltransferase gene (schS6) from Streptomyces sp. SCC-2136. J. Microbiol. Biotechnol. 17: 685-690
  16. He, X. M. and H. W. Liu. 2002. Formation of unusual sugars: Mechanistic studies and biosynthetic applications. Annu. Rev. Biochem. 71: 701-754 https://doi.org/10.1146/annurev.biochem.71.110601.135339
  17. Hoeksema, H. and J. C. Knight. 1975. The production of dihydrospectinomycin by Streptomyces spectabilis. J. Antibiot. 28: 240-241 https://doi.org/10.7164/antibiotics.28.240
  18. Hong, J. S., S. H. Park, C. Y. Choi, J. K. Sohng, and Y. J. Yoon. 2004. New olivosyl derivatives of methymycin/ pikromycin from an engineered strain of Streptomyces venezuelae. FEMS Microbiol. Lett. 238: 391-399
  19. Hong, J. S., S. J. Park, N. Parajuli, S. R. Park, H. S. Koh, W. S. Jung, C. Y. Choi, and Y. J. Yoon. 2007. Functional analysis of desVIII homologues involved in glycosylation of macrolide antibiotics by interspecies complementation. Gene 386: 123-130 https://doi.org/10.1016/j.gene.2006.08.021
  20. Hong, J. S., W. S. Jung, S. K. Lee, W. S. Koh, H. S. Park, S. J. Park, Y. S. Kim, and Y. J. Yoon. 2005. The role of a second protein (DesVIII) in glycosylation for the biosynthesis of hybrid macrolide antibiotics in Streptomyces venezuelae. J. Microbiol. Biotechnol. 15: 640-645
  21. Hooper, D. C., J. S. Wolfson, G. L. McHugh, M. B. Winters, and M. N. Swartz. 1982. Effects of novobiocin, coumermycin A1, clorobiocin, and their analogs on Escherichia coli DNA gyrase and bacterial growth. Antimicrob. Agents Chemother. 22: 662-671 https://doi.org/10.1128/AAC.22.4.662
  22. Huang, F., S. F. Haydock, T. Mironenko, D. Spiteller, Y. Li, and J. B. Spencer. 2005. The neomycin biosynthetic gene cluster of Streptomyces fradiae NCIMB 8233: Characterization of an aminotransferase involved in the formation of 2-deoxystreptamine. Org. Biomol. Chem. 3: 1410-1419 https://doi.org/10.1039/b501199j
  23. Huang, F., D. Spiteller, N. A. Koorbanally, Y. Li, N. M. Llewellyn, and J. B. Spencer. 2007. Elaboration of neosamine rings in the biosynthesis of neomycin and butirosin. Chembiochem 8: 283-288 https://doi.org/10.1002/cbic.200600371
  24. Jaishy, B. P., S. K. Lim, I. D. Yoo, J. C. Yoo, J. K. Sohng, and D. H. Nam. 2006. Cloning and characterization of a gene cluster for the production of polyketide macrolide dihydrochalcomycin in Streptomyces sp. KCTC 0041BP. J. Microbiol. Biotechnol. 16: 764-770
  25. Jo, Y. Y., S. H. Kim, Y. Y. Yang, C. M. Kang, J. K. Sohng, and J. W. Suh. 2003. Functional analysis of spectinomycin biosynthetic genes from Streptomyces spectabilis ATCC27741. J. Microbiol. Biotechnol. 13: 906-911
  26. Jung, W. S., A. R. Han, J. S. Hong, S. R. Park, C. Y. Choi, J. W. Park, and Y. J. Yoon. 2007. Bioconversion of 12-, 14-, and 16-membered ring aglycones to glycosylated macrolides in an engineered strain of Streptomyces venezuelae. Appl. Microbiol. Biotechnol. 76: 1373-1381 https://doi.org/10.1007/s00253-007-1101-y
  27. Kang, Y. B., Y. H. Yang, K. W. Lee, S. G. Lee, J. K. Sohng, H. C. Lee, K. Liou, and B. G. Kim. 2006. Preparative synthesis of dTDP-L-rhamnose through combined enzymatic pathways. Biotechnol. Bioeng. 93: 21-27 https://doi.org/10.1002/bit.20648
  28. Kharel, M. K., D. B. Basnet, H. C. Lee, K. Liou, Y. H. Moon, J. J. Kim, J. S. Woo, and J. K. Sohng. 2004. Molecular cloning and characterization of a 2-deoxystreptamine biosynthetic gene cluster in gentamicin-producing Micromonospora echinospora ATCC 15835. Mol. Cells 18: 71-78
  29. Kharel, M. K., D. B. Basnet, H. C. Lee, K. Liou, J. S. Woo, B. G. Kim, and J. K. Sohng. 2004. Isolation and characterization of the tobramycin biosynthetic gene cluster from Streptomyces tenebrarius. FEMS Microbiol. Lett. 230: 185-190 https://doi.org/10.1016/S0378-1097(03)00881-4
  30. Kharel, M. K., B. Subba, D. B. Basnet, J. S. Woo, H. C. Lee, K. Liou, and J. K. Sohng. 2004. A gene cluster for biosynthesis of kanamycin from Streptomyces kanamyceticus: Comparison with gentamicin biosynthetic gene cluster. Arch. Biochem. Biophys. 429: 204-214 https://doi.org/10.1016/j.abb.2004.06.009
  31. Kharel, M. K., B. Subba, H. C. Lee, K. Liou, J. S. Woo, and J. K. Sohng. 2003. An approach for cloning biosynthetic genes of 2-deoxystreptamine-containing aminocyclitol antibiotics: Isolation of a biosynthetic gene cluster of tobramycin from Streptomyces tenebrarius. Biotechnol. Lett. 25: 2041-2047 https://doi.org/10.1023/B:BILE.0000007063.66429.90
  32. Khosla, C. and R. J. X. Zawada. 1996. Generation of polyketide libraries via combinatorial biosynthesis. Trends Biotechnol. 14: 2465-2497
  33. Kim, B. C., J. M. Lee, J. S. Ahn, and B. S. Kim. 2007. Cloning, sequencing, and characterization of the pradimicin biosynthetic gene cluster of Actinomadura hibisca P157-2. J. Microbiol. Biotechnol. 17: 830-839
  34. Kim, C. Y., H. J. Park, and E. S. Kim. 2006. Functional dissection of sigma-like domain in antibiotic regulatory gene, afsR2 in Streptomyces lividans. J. Microbiol. Biotechnol. 16: 1477-1480
  35. Kim, K. P., C. S. Shin, S. J. Lee, J. H. Kim, J. M. Young, Y. Y. Lee, J. H. Ahn, J. W. Suh, and Y. G. Lim. 2006. Proteomes induced by S-adenosyl-L-methionine in Streptomyces coelicolor A3(2). J. Microbiol. Biotechnol. 16: 799-803
  36. Kudo, F., M. Numakura, H. Tamegai, H. Yamamoto, T. Eguchi, and K. Kakinuma. 2005. Extended sequence and functional analysis of the butirosin biosynthetic gene cluster in Bacillus circulans SANK 72073. J. Antibiot. 58: 373-379 https://doi.org/10.1038/ja.2005.47
  37. Kudo, F., Y. Yamamoto, K. Yokoyama, T. Eguchi, and K. Kakinuma. 2005. Biosynthesis of 2-deoxystreptamine by three crucial enzymes in Streptomyces fradiae NBRC 12773. J. Antibiot. 58: 766-774 https://doi.org/10.1038/ja.2005.104
  38. Lamichhane, J., K. Liou, H. C. Lee, C. G. Kim, and J. K. Sohng. 2006. Functional characterization of ketoreductase (rubN6) and aminotransferase (rubN4) genes in the gene cluster of Streptomyces achromogenes var. rubradiris. Biotechnol. Lett. 28: 545-553 https://doi.org/10.1007/s10529-006-0013-8
  39. Langenhan, J. M., N. R. Peters, I. A. Guzei, F. M. Hoffmann, and J. S. Thorson. 2005. Enhancing the anticancer properties of cardiac glycosides by neoglycorandomization. Proc. Natl. Acad. Sci. USA 102: 12305-12310
  40. Leadly, P. F. 1997. Combinatorial approaches to polyketide biosynthesis. Curr. Opin. Chem. Biol. 1: 335-341
  41. Lee, H. C., J. K. Sohng, H. J. Kim, D. H. Nam, J. M. Han, S. S. Cho, J. H. Choi, and J. C. Yoo. 2004. Cloning and expression of the glucose-1-phosphate thymidylyltransferase gene (gerD) from Streptomyces sp. GERI-155. Mol. Cells 17: 274-280
  42. Lee, H. C., J. K. Sohng, H. J. Kim, D. H. Nam, C. N. Seong, J. M. Han, and J. C. Yoo. 2004. Cloning, expression, and biochemical characterization of dTDP-glucose 4,6-dehydratase gene (gerE) from Streptomyces sp. GERI-155. J. Microbiol. Biotechnol. 14: 576-583
  43. Lee, S. K., J. W. Park, J. W. Kim, W. S. Jung, S. R. Park, C. Y. Choi, E. S. Kim, B. S. Kim, J. S. Ahn, D. H. Sherman, and Y. J. Yoon. 2006. Neopikromycin and novapikromycin from the pikromycin biosynthetic pathway of Streptomyces venezuelae. J. Nat. Prod. 69: 847-849 https://doi.org/10.1021/np060026p
  44. Lee, S. K., J. W. Park, S. R. Park, J. S. Ahn, C. Y. Choi, and Y. J. Yoon. 2006. Hydroxylation of indole by PikC cytochrome P450 from Streptomyces venezuelae and engineering its catalytic activity by site-directed mutagenesis. J. Microbiol. Biotechnol. 16: 974-978
  45. Lee, Y. Y., J. M. Young, H. J. Kwon, J. W. Suh, J. Y. Kim, Y. H. Chong, and Y. H. Lim. 2006. AdoMet derivatives induce the production of actinorhodin in Streptomyces coelicolor. J. Microbiol. Biotechnol. 16: 965-968
  46. Litovchick, A., A. Lapidot, M. Eisenstein, A. Kalinkovich, and G. Borkow. 2001. Neomycin B-arginine conjugate, a novel HIV-1 Tat antagonist: Synthesis and anti-HIV activities. Biochemistry 40: 15612-15623 https://doi.org/10.1021/bi0108655
  47. Lu, W., C. Leimkuhler, G. J. Jr Gatto, R. G. Kruger, M. Oberthur, D. Kahne, and C. T. Walsh. 2005. AknT is an activating protein for the glycosyltransferase AknS in Laminodeoxysugar transfer to the aglycone of aclacinomycin A. Chem. Biol. 12: 527-534 https://doi.org/10.1016/j.chembiol.2005.02.016
  48. Madduri, K. and C. R. Hutchinson. 1995. Functional characterization and transcriptional analysis of the dnrR1 locus, which controls daunorubicin biosynthesis in Streptomyces peucetius. J. Bacteriol. 177: 1208-1215 https://doi.org/10.1128/jb.177.5.1208-1215.1995
  49. Maharjan, J., K. Liou, H. C. Lee, C. G. Kim, J. J. Lee, J. C. Yoo, and J. K. Sohng. 2003. Functional identification of rub52 gene involved in the biosynthesis of rubradirin. Biotechnol. Lett. 25: 909-915 https://doi.org/10.1023/A:1024075902143
  50. Mason, D. J., A. Dietz, and R. M. Smith. 1961. Actinospectacin, a new antibiotic. I. Discovery and biological properties. Antibiot. Chemother. 11: 118-122
  51. Melancon, C. E. III, H. Takahashi, and H. W. Liu. 2004. Characterization of TylM3/TylM2 and MydC/MycB pairs required for efficient glycosyltransfer in macrolide antibiotic biosynthesis. J. Am. Chem. Soc. 126: 16726- 16727 https://doi.org/10.1021/ja043900e
  52. Newman, D. J., G. M. Cragg, and K. M. Snader. 2003. Natural products as sources of new drugs over the period 1981-2002. J. Nat. Prod. 66: 1022-1037 https://doi.org/10.1021/np030096l
  53. Oh, J., S. G. Lee, B. G. Kim, J. K. Sohng, K. Liou, and H. C. Lee. 2003. One-pot enzymatic production of dTDP-4-keto- 6-deoxy-D-glucose from dTMP and glucose-1-phosphate. Biotechnol. Bioeng. 84: 452-458 https://doi.org/10.1002/bit.10789
  54. Park, N. S., H. J. Park, K. B. Han, and E. S. Kim. 2006. Heterologous expression of novel cytochrome P450 hydroxylase genes from Sebekia benihana. J. Microbiol. Biotechnol. 16: 295-298
  55. Poulsen, S. M., C. Kofoed, and B. Vester. 2000. Inhibition of the ribosomal peptidyl transferase reaction by the mycarose moiety of the antibiotics carbomycin, spiramycin and tylosin. J. Mol. Biol. 304: 471-481 https://doi.org/10.1006/jmbi.2000.4229
  56. Rajkarnikar, A., H. J. Kwon, Y. W. Ryu, and J. W. Suh. 2007. Two threonine residues required for role of AfsKav in controlling morphogenesis and avermectin production in Streptomyces avermitilis. J. Microbiol. Biotechnol. 17: 1563-1567
  57. Rodriguez, L., I. Aguirrezabalaga, N. Allende, A. F. Brana, C. Mendez, and J. A. Salas. 2002. Engineering deoxysugar biosynthetic pathways from antibiotic-producing microorganisms. A tool to produce novel glycosylated bioactive compounds. Chem. Biol. 9: 721-729 https://doi.org/10.1016/S1074-5521(02)00154-0
  58. Sohng, J. K., H. J. Kim, D. H. Nam, D. O. Lim, J. M. Han, H. J. Lee, and J. C. Yoo. 2004. Cloning, expression, and biological function of a dTDP-deoxyglucose epimerase (gerF) gene from Streptomyces sp. GERI-155. Biotechnol. Lett. 26: 185-191 https://doi.org/10.1023/B:BILE.0000013709.80691.97
  59. Sohng, J. K., T. J. Oh, J. H. Cha, J. J. Hahn, J. W. Kim, J. W. Suh, and H. C. Lee. 2001. Cloning and identification of a gene cluster in Streptomyces spectabilis - spectinomycin producer. J. Biochem. Mol. Biol. Biophys. 5: 209-218
  60. Sohng, J. K., T. J. Oh, and C. G. Kim. 1998. Method for cloning biosynthetic genes of secondary metabolites including deoxysugar from Actinomycetes. J. Biochem. Mol. Biol. 31: 475-483
  61. Sohng, J. K., T. J. Oh, J. J. Lee, and C. G. Kim. 1997. Identification of a gene cluster of biosynthetic genes of rubradirin substructures in S. achromogenes var. rubradiris NRRL 3061. Mol. Cells 7: 674-681
  62. Solenberg, P. J., P. Matsushima, D. R. Stack, S. C. Wilkie, R. C. Thompson, and R. H. Baltz. 1997. Production of hybrid glycopeptide antibiotics in vitro and in Streptomyces toyocaensis. Chem. Biol. 4: 195-202 https://doi.org/10.1016/S1074-5521(97)90288-X
  63. Steffensky, M., A. Muhlenweg, Z. X. Wang, S. M. Li, and L. Heide. 2000. Identification of the novobiocin biosynthetic gene cluster of Streptomyces spheroides NCIB 11891. Antimicrob. Agents Chemother. 44: 1214-1222 https://doi.org/10.1128/AAC.44.5.1214-1222.2000
  64. Subba, B., M. K. Kharel, H. C. Lee, K. Liou, B. G. Kim, and J. K. Sohng. 2005. The ribostamycin biosynthetic gene cluster in Streptomyces rebosidificus: Comparison with butirosin biosynthesis. Mol. Cells 20: 90-96
  65. Subba, B., N. P. Kurumbang, Y. S. Jung, Y. J. Yoon, H. C. Lee, K. Liou, and J. K. Sohng. 2007. Production of aminoglycoside in non-aminoglycoside producing Streptomyces lividans. Bioorg. Med. Chem. Lett. 17: 1892-1896 https://doi.org/10.1016/j.bmcl.2007.01.035
  66. Thuy, M. L., M. K. Kharel, R. Lamichhane, H. C. Lee, J. W. Suh, K. Liou, and J. K. Sohng. 2005. Expression of 2-deoxyscyllo- inosose synthase (kanA) from kanamycin gene cluster in Streptomyces lividans. Biotechnol. Lett. 27: 465-470 https://doi.org/10.1007/s10529-005-2222-y
  67. Thuy, T. T., H. C. Lee, C. G. Kim, L. Heide, and J. K. Sohng. 2005. Functional characterizations of novWUS involved in novobiocin biosynthesis from Streptomyces spheroides. Arch. Biochem. Biophys. 436: 161-167 https://doi.org/10.1016/j.abb.2005.01.012
  68. Thuy, T. T., K. Liou, T. J. Oh, D. H. Kim, D. H. Nam, J. C. Yoo, and J. K. Sohng. 2007. Biosynthesis of dTDP-6-deoxybeta- D-allose, biochemical characterization of dTDP-4-keto- 6-deoxyglucose reductase (gerK1) from Streptomyces sp. KCTC 0041BP. Glycobiology 17: 119-126 https://doi.org/10.1093/glycob/cwl060
  69. Tok, J. B., L. J. Dunn, and R. C. Des Jean. 2001. Binding of dimeric aminoglycosides to the HIV-1 rev responsive element (RRE) RNA constructs. Bioorg. Med. Chem. Lett. 11: 1127-1131 https://doi.org/10.1016/S0960-894X(01)00149-4
  70. Truman, A. W., F. Huang, N. M. Llewellyn, and J. B. Spencer. 2007. Characterization of the enzyme BtrD from Bacillus circulans and revision of its functional assignment in the biosynthesis of butirosin. Angew. Chem. Int. Ed. Engl. 46: 1462-1464 https://doi.org/10.1002/anie.200604194
  71. Tsuchizaki, N., K. Ishino, F. Saito, J. Ishikawa, M. Nakajima, and K. Hotta. 2006. Trends of Arbekacin-resistant MRSA strains in Japanese hospitals (1979 to 2000). J. Antibiot. 59: 229-233 https://doi.org/10.1038/ja.2006.32
  72. Waldron, C., P. Matsushima, P. R. Jr. Rosteck, M. C. Broughton, J. Turner, K. Madduri, K. P. Crawford, D. J. Merlo, and R. H. Baltz. 2001. Cloning and analysis of the spinosad biosynthetic gene cluster of Saccharopolyspora spinosa. Chem. Biol. 8: 487-499 https://doi.org/10.1016/S1074-5521(01)00029-1
  73. Weber, J. M., J. O. Leung, S. J. Swanson, K. B. Ikler, and J. B. McAlpine. 1991. An erythromycin derivative produced by targeted gene disruption in Saccharopolyspora erythraea. Science 252: 114-117 https://doi.org/10.1126/science.2011746
  74. Wehrli, W. 1977. Ansamycins. Chemistry, biosynthesis and biological activity. Top. Curr. Chem. 72: 21-49 https://doi.org/10.1007/BFb0048448
  75. Xue, Y., L. Zhao, H. W. Liu, and D. H. Sherman. 1998. A gene cluster for macrolide antibiotic biosynthesis in Streptomyces venezuelae: Architecture of metabolic diversity. Proc. Natl. Acad. Sci. USA 95: 12111-12116
  76. Zhang, G., J. Shen, H. Cheng, L. Zhu, L. Fang, S. Luo, M. T. Muller, G. E. Lee, L. Wei, Y. Du, D. Sun, and P. G. Wang. 2005. Syntheses and biological activities of rebeccamycin analogues with uncommon sugars. J. Med. Chem. 48: 2600- 2611 https://doi.org/10.1021/jm0493764
  77. Zhao, X. Q., Y. Y. Jin, H. J. Kwon, Y. Y. Yang, and J. W. Suh. 2006. S-Adenosylmethionine (SAM) regulates antibiotic biosynthesis in Streptomyces spp. in a mode independent of its role as a methyl donor. J. Microbiol. Biotechnol. 16: 927- 932
  78. Zhu, L., X. Cao, W. Chen, G. Zhang, D. Sun, and P. G. Wang. 2005. Syntheses and biological activities of daunorubicin analogs with uncommon sugars. Bioorg. Med. Chem. 13: 6381-6387 https://doi.org/10.1016/j.bmc.2005.06.053