Production of hybrid 16-membered macrolides by expressing combinations of polyketide synthase genes in engineered Streptomyces fradiae hosts.
Combinations of the five polyketide synthase (PKS) genes for biosynthesis of tylosin in Streptomyces fradiae (tylG), spiramycin in Streptomyces ambofaciens (srmG), or chalcomycin in Streptomyces bikiniensis (chmG) were expressed in engineered hosts derived from a tylosin-producing strain of S. fradiae. Surprisingly efficient synthesis of compounds predicted from the expressed hybrid PKS was obtained. The post-PKS tailoring enzymes of tylosin biosynthesis acted efficiently on the hybrid intermediates with the exception of TylH-catalyzed hydroxylation of the methyl group at C14, which was efficient if C4 bore a methyl group, but inefficient if a methoxyl was present. Moreover, for some compounds, oxidation of the C6 ethyl side chain to an unprecedented carboxylic acid was observed. By also expressing chmH, a homolog of tylH from the chalcomycin gene cluster, efficient hydroxylation of the 14-methyl group was restored.
Kosan Biosciences, Inc., 3832 Bay Center Place, Hayward, California 94545, USA. reeves@kosan.com
Christopher D
CD
Reeves
Shannon L
SL
Ward
W Peter
WP
Revill
Hideki
H
Suzuki
Matthew
M
Marcus
Oleg V
OV
Petrakovsky
Saul
S
Marquez
Hong
H
Fu
Steven D
SD
Dong
Leonard
L
Katz
D018942:Macrolides / Q000138:chemical synthesis* / Q000737:chemistry / Q000378:metabolism; D048630:Polyketide Synthases / Q000096:biosynthesis* / Q000235:genetics* / Q000378:metabolism; D015202:Protein Engineering / Q000379:methods*; D013302:Streptomyces / Q000235:genetics* / Q000378:metabolism
D018942:Macrolides; D048630:Polyketide Synthases