Heterologous expression of tylosin polyketide synthase and production of a hybrid bioactive macrolide in Streptomyces venezuelae.
Tylosin polyketide synthase (Tyl PKS) was heterologously expressed in an engineered strain of Streptomyces venezuelae bearing a deletion of pikromycin PKS gene cluster using two compatible low-copy plasmids, each under the control of a pikAI promoter. The mutant strain produced 0.5 mg/l of the 16-membered ring macrolactone, tylactone, after a 4-day culture, which is a considerably reduced culture period to reach the maximum production level compared to other Streptomyces hosts. To improve the production level of tylactone, several precursors for ethylmalonyl-CoA were fed to the growing medium, leading to a 2.8-fold improvement (1.4 mg/ml); however, switching the pikAI promoter to an actI promoter had no observable effect. In addition, a small amount of desosamine-glycosylated tylactone was detected from the extract of the mutant strain, revealing that the native glycosyltransferase DesVII displayed relaxed substrate specificity in accepting the 16-membered ring macrolactone to produce the glycosylated tylactone. These results demonstrate a successful attempt for a heterologous expression of Tyl PKS in S. venezuelae and introduce S. venezuelae as a rapid heterologous expression system for the production of secondary metabolites.
Interdisciplinary Program of Biochemical Engineering and Biotechnology, Seoul National University, San 56-1, Shilim-dong, Gwanak-gu, Seoul 151-742, South Korea.
Won Seok
WS
Jung
Sang Kil
SK
Lee
Jay Sung Joong
JS
Hong
Sung Ryeol
SR
Park
Soon Jeong
SJ
Jeong
Ah Reum
AR
Han
Jae Kyung
JK
Sohng
Byung Gee
BG
Kim
Cha Yong
CY
Choi
David H
DH
Sherman
Yeo Joon
YJ
Yoon
D000900:Anti-Bacterial Agents / Q000096:biosynthesis / Q000737:chemistry; D005818:Genetic Engineering; D018942:Macrolides / Q000378:metabolism*; D009097:Multienzyme Complexes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010957:Plasmids / Q000235:genetics; D013302:Streptomyces / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism*; D015645:Tylosin / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism
D000900:Anti-Bacterial Agents; D018942:Macrolides; D009097:Multienzyme Complexes; D015645:Tylosin