Details
| Original language | English |
|---|---|
| Pages (from-to) | 699-711 |
| Number of pages | 13 |
| Journal | Chemistry and Biology |
| Volume | 5 |
| Issue number | 12 |
| Publication status | Published - Dec 1998 |
| Externally published | Yes |
Abstract
Background: It has been proposed that Streptomyces malonyl CoA:holo acyl carrier protein transacylases (MCATs) provide a link between fatty acid and polyketide biosynthesis. Two recent studies have provided evidence that the presence of MCAT is essential for polyketide synthesis to proceed in reconstituted minimal polyketide synthases (PKSs). In contrast to this, we previously showed that the holo acyl carrier proteins (ACPs) from type II PKSs are capable of catalytic self-malonylation in the presence of malonyl CoA, which suggests that MCAT might not be necessary for polyketide biosynthesis. Results: We reconstituted a homologous actinorhodin (act) type II minimal PKS in vitro. When act holo-ACP is present in limiting concentrations, MCAT is required by the synthase complex in order for polyketide biosynthesis to proceed. When holo-ACP is present in excess, however, efficient polyketide synthesis proceeds without MCAT. The rate of polyketide production increases with holo-ACP concentration, but at low ACP concentration or equimolar ACP:KS:CLF (KS, ketosynthase; CLF, chain length determining factor) concentrations this rate is significantly lower than expected, indicating that free holo-ACP is sequestered by the KS/CLF complex. Conclusions: The rate of polyketide biosynthesis is dictated by the ratio of holo-ACP to KS and CLF, as well as by the total protein concentration. There is no absolute requirement for MCAT in polyketide biosynthesis in vitro, although the role of MCAT during polyketide synthesis in vivo remains an open question. MCAT might be responsible for the rate enhancement of malonyl transfer at very low free holo-ACP concentrations or it could be required to catalyse the transfer of malonyl groups from malonyl CoA to sequestered holo-ACP.
Keywords
- Actinorhodin biosynthesis, Fatty acid synthase, Holo acyl carrier protein, Malonyl transferase, Polyketide synthase
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)
- Biochemistry
- Biochemistry, Genetics and Molecular Biology(all)
- Molecular Medicine
- Biochemistry, Genetics and Molecular Biology(all)
- Molecular Biology
- Pharmacology, Toxicology and Pharmaceutics(all)
- Pharmacology
- Pharmacology, Toxicology and Pharmaceutics(all)
- Drug Discovery
- Biochemistry, Genetics and Molecular Biology(all)
- Clinical Biochemistry
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In: Chemistry and Biology, Vol. 5, No. 12, 12.1998, p. 699-711.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - MCAT is not required for in vitro polyketide synthesis in a minimal actinorhodin polyketide synthase from Streptomyces coelicolor
AU - Matharu, Anne Lise
AU - Cox, Russell J.
AU - Crosby, John
AU - Byrom, Kate J.
AU - Simpson, Thomas J.
N1 - Funding information: This work was supported by a grant from the Biotechnology and Biological Sciences Research Council (BBSRC, PAC 02678) and a Royal Society
PY - 1998/12
Y1 - 1998/12
N2 - Background: It has been proposed that Streptomyces malonyl CoA:holo acyl carrier protein transacylases (MCATs) provide a link between fatty acid and polyketide biosynthesis. Two recent studies have provided evidence that the presence of MCAT is essential for polyketide synthesis to proceed in reconstituted minimal polyketide synthases (PKSs). In contrast to this, we previously showed that the holo acyl carrier proteins (ACPs) from type II PKSs are capable of catalytic self-malonylation in the presence of malonyl CoA, which suggests that MCAT might not be necessary for polyketide biosynthesis. Results: We reconstituted a homologous actinorhodin (act) type II minimal PKS in vitro. When act holo-ACP is present in limiting concentrations, MCAT is required by the synthase complex in order for polyketide biosynthesis to proceed. When holo-ACP is present in excess, however, efficient polyketide synthesis proceeds without MCAT. The rate of polyketide production increases with holo-ACP concentration, but at low ACP concentration or equimolar ACP:KS:CLF (KS, ketosynthase; CLF, chain length determining factor) concentrations this rate is significantly lower than expected, indicating that free holo-ACP is sequestered by the KS/CLF complex. Conclusions: The rate of polyketide biosynthesis is dictated by the ratio of holo-ACP to KS and CLF, as well as by the total protein concentration. There is no absolute requirement for MCAT in polyketide biosynthesis in vitro, although the role of MCAT during polyketide synthesis in vivo remains an open question. MCAT might be responsible for the rate enhancement of malonyl transfer at very low free holo-ACP concentrations or it could be required to catalyse the transfer of malonyl groups from malonyl CoA to sequestered holo-ACP.
AB - Background: It has been proposed that Streptomyces malonyl CoA:holo acyl carrier protein transacylases (MCATs) provide a link between fatty acid and polyketide biosynthesis. Two recent studies have provided evidence that the presence of MCAT is essential for polyketide synthesis to proceed in reconstituted minimal polyketide synthases (PKSs). In contrast to this, we previously showed that the holo acyl carrier proteins (ACPs) from type II PKSs are capable of catalytic self-malonylation in the presence of malonyl CoA, which suggests that MCAT might not be necessary for polyketide biosynthesis. Results: We reconstituted a homologous actinorhodin (act) type II minimal PKS in vitro. When act holo-ACP is present in limiting concentrations, MCAT is required by the synthase complex in order for polyketide biosynthesis to proceed. When holo-ACP is present in excess, however, efficient polyketide synthesis proceeds without MCAT. The rate of polyketide production increases with holo-ACP concentration, but at low ACP concentration or equimolar ACP:KS:CLF (KS, ketosynthase; CLF, chain length determining factor) concentrations this rate is significantly lower than expected, indicating that free holo-ACP is sequestered by the KS/CLF complex. Conclusions: The rate of polyketide biosynthesis is dictated by the ratio of holo-ACP to KS and CLF, as well as by the total protein concentration. There is no absolute requirement for MCAT in polyketide biosynthesis in vitro, although the role of MCAT during polyketide synthesis in vivo remains an open question. MCAT might be responsible for the rate enhancement of malonyl transfer at very low free holo-ACP concentrations or it could be required to catalyse the transfer of malonyl groups from malonyl CoA to sequestered holo-ACP.
KW - Actinorhodin biosynthesis
KW - Fatty acid synthase
KW - Holo acyl carrier protein
KW - Malonyl transferase
KW - Polyketide synthase
UR - http://www.scopus.com/inward/record.url?scp=0032401977&partnerID=8YFLogxK
U2 - 10.1016/S1074-5521(98)90663-9
DO - 10.1016/S1074-5521(98)90663-9
M3 - Article
AN - SCOPUS:0032401977
VL - 5
SP - 699
EP - 711
JO - Chemistry and Biology
JF - Chemistry and Biology
SN - 1074-5521
IS - 12
ER -