The acyltransferase homologue from the initiation module of the R1128 polyketide synthase is an Acyl-ACP thioesterase that edits acetyl primer units

Yi Tang, Andrew T Koppisch, Chaitan Khosla

Research output: Contribution to journalArticle

37 Citations (Scopus)

Abstract

Type II polyketide synthases (PKSs) synthesize polyfunctional aromatic polyketides through iterative condensations of malonyl extender units. The biosynthesis of most aromatic polyketides is initiated through an acetate unit derived from decarboxylation of malonyl-acyl carrier protein (ACP). Modification of this primer unit represents a powerful method of generating novel polyketides. We have demonstrated that recombination of the initiation module from the R1128 PKS with heterologous elongation modules afforded regioselectively modified polyketides containing alternative primer units. With the exception of the role of the acyltransferase homologue ZhuC, the catalytic cycle of the initiation module has been well explored. ZhuC, along with the ketosynthase III homologue ZhuH and the ACPp ZhuG, is essential for the in vivo biosynthesis of aromatic polyketides derived from non-acetate primer units. Here we have studied the role of ZhuC using PKS proteins reconstituted in vitro. We show that the tetracenomycin (tcm) minimal PKS can be directly primed with non-acetate acyl groups. In the presence of ∼10 μM hexanoyl-ZhuG or ∼100 μM hexanoyl-CoA, the tcm minimal PKS synthesized hexanoyl-primed analogues of octaketides SEK4 and SEK4b, as well as acetate-primed decaketides SEK15 and SEK15b at comparable levels. Addition of ZhuC abolished synthesis of the acetate-primed decaketides, resulting in exclusive synthesis of the hexanoyl-primed octaketides. In the absence of alternative acyl donors, ZhuC severely retarded the activity of the tcm minimal PKS. The editing capabilities of ZhuC were directly revealed by demonstrating that ZhuC has 100 times greater specificity for acetyl- and propionyl-ACP as compared to hexanoyl- and octanoyl-ACP. Thus, by purging the acetate primer units that otherwise dominate polyketide chain initiation, ZhuC (and presumably its homologues in other PKSs such as the doxorubicin and frenolicin PKSs) allows alternative primer units to be utilized by the elongation module in vivo. The abilities of other alkylacyl primer units to prime the tcm minimal PKS were also investigated in this report.

Original languageEnglish (US)
Pages (from-to)9546-9555
Number of pages10
JournalBiochemistry
Volume43
Issue number29
DOIs
StatePublished - Jul 27 2004
Externally publishedYes

Fingerprint

Polyketide Synthases
Acyltransferases
Polyketides
Acyl Carrier Protein
Acetates
Biosynthesis
Elongation
Decarboxylation
oleoyl-(acyl-carrier-protein) hydrolase
Purging
Genetic Recombination
Doxorubicin
Condensation
5838 DNI

ASJC Scopus subject areas

  • Biochemistry

Cite this

The acyltransferase homologue from the initiation module of the R1128 polyketide synthase is an Acyl-ACP thioesterase that edits acetyl primer units. / Tang, Yi; Koppisch, Andrew T; Khosla, Chaitan.

In: Biochemistry, Vol. 43, No. 29, 27.07.2004, p. 9546-9555.

Research output: Contribution to journalArticle

@article{6be2a9d7dcc246c8a4ef8fc7f0b22c4f,
title = "The acyltransferase homologue from the initiation module of the R1128 polyketide synthase is an Acyl-ACP thioesterase that edits acetyl primer units",
abstract = "Type II polyketide synthases (PKSs) synthesize polyfunctional aromatic polyketides through iterative condensations of malonyl extender units. The biosynthesis of most aromatic polyketides is initiated through an acetate unit derived from decarboxylation of malonyl-acyl carrier protein (ACP). Modification of this primer unit represents a powerful method of generating novel polyketides. We have demonstrated that recombination of the initiation module from the R1128 PKS with heterologous elongation modules afforded regioselectively modified polyketides containing alternative primer units. With the exception of the role of the acyltransferase homologue ZhuC, the catalytic cycle of the initiation module has been well explored. ZhuC, along with the ketosynthase III homologue ZhuH and the ACPp ZhuG, is essential for the in vivo biosynthesis of aromatic polyketides derived from non-acetate primer units. Here we have studied the role of ZhuC using PKS proteins reconstituted in vitro. We show that the tetracenomycin (tcm) minimal PKS can be directly primed with non-acetate acyl groups. In the presence of ∼10 μM hexanoyl-ZhuG or ∼100 μM hexanoyl-CoA, the tcm minimal PKS synthesized hexanoyl-primed analogues of octaketides SEK4 and SEK4b, as well as acetate-primed decaketides SEK15 and SEK15b at comparable levels. Addition of ZhuC abolished synthesis of the acetate-primed decaketides, resulting in exclusive synthesis of the hexanoyl-primed octaketides. In the absence of alternative acyl donors, ZhuC severely retarded the activity of the tcm minimal PKS. The editing capabilities of ZhuC were directly revealed by demonstrating that ZhuC has 100 times greater specificity for acetyl- and propionyl-ACP as compared to hexanoyl- and octanoyl-ACP. Thus, by purging the acetate primer units that otherwise dominate polyketide chain initiation, ZhuC (and presumably its homologues in other PKSs such as the doxorubicin and frenolicin PKSs) allows alternative primer units to be utilized by the elongation module in vivo. The abilities of other alkylacyl primer units to prime the tcm minimal PKS were also investigated in this report.",
author = "Yi Tang and Koppisch, {Andrew T} and Chaitan Khosla",
year = "2004",
month = "7",
day = "27",
doi = "10.1021/bi049157k",
language = "English (US)",
volume = "43",
pages = "9546--9555",
journal = "Biochemistry",
issn = "0006-2960",
publisher = "American Chemical Society",
number = "29",

}

TY - JOUR

T1 - The acyltransferase homologue from the initiation module of the R1128 polyketide synthase is an Acyl-ACP thioesterase that edits acetyl primer units

AU - Tang, Yi

AU - Koppisch, Andrew T

AU - Khosla, Chaitan

PY - 2004/7/27

Y1 - 2004/7/27

N2 - Type II polyketide synthases (PKSs) synthesize polyfunctional aromatic polyketides through iterative condensations of malonyl extender units. The biosynthesis of most aromatic polyketides is initiated through an acetate unit derived from decarboxylation of malonyl-acyl carrier protein (ACP). Modification of this primer unit represents a powerful method of generating novel polyketides. We have demonstrated that recombination of the initiation module from the R1128 PKS with heterologous elongation modules afforded regioselectively modified polyketides containing alternative primer units. With the exception of the role of the acyltransferase homologue ZhuC, the catalytic cycle of the initiation module has been well explored. ZhuC, along with the ketosynthase III homologue ZhuH and the ACPp ZhuG, is essential for the in vivo biosynthesis of aromatic polyketides derived from non-acetate primer units. Here we have studied the role of ZhuC using PKS proteins reconstituted in vitro. We show that the tetracenomycin (tcm) minimal PKS can be directly primed with non-acetate acyl groups. In the presence of ∼10 μM hexanoyl-ZhuG or ∼100 μM hexanoyl-CoA, the tcm minimal PKS synthesized hexanoyl-primed analogues of octaketides SEK4 and SEK4b, as well as acetate-primed decaketides SEK15 and SEK15b at comparable levels. Addition of ZhuC abolished synthesis of the acetate-primed decaketides, resulting in exclusive synthesis of the hexanoyl-primed octaketides. In the absence of alternative acyl donors, ZhuC severely retarded the activity of the tcm minimal PKS. The editing capabilities of ZhuC were directly revealed by demonstrating that ZhuC has 100 times greater specificity for acetyl- and propionyl-ACP as compared to hexanoyl- and octanoyl-ACP. Thus, by purging the acetate primer units that otherwise dominate polyketide chain initiation, ZhuC (and presumably its homologues in other PKSs such as the doxorubicin and frenolicin PKSs) allows alternative primer units to be utilized by the elongation module in vivo. The abilities of other alkylacyl primer units to prime the tcm minimal PKS were also investigated in this report.

AB - Type II polyketide synthases (PKSs) synthesize polyfunctional aromatic polyketides through iterative condensations of malonyl extender units. The biosynthesis of most aromatic polyketides is initiated through an acetate unit derived from decarboxylation of malonyl-acyl carrier protein (ACP). Modification of this primer unit represents a powerful method of generating novel polyketides. We have demonstrated that recombination of the initiation module from the R1128 PKS with heterologous elongation modules afforded regioselectively modified polyketides containing alternative primer units. With the exception of the role of the acyltransferase homologue ZhuC, the catalytic cycle of the initiation module has been well explored. ZhuC, along with the ketosynthase III homologue ZhuH and the ACPp ZhuG, is essential for the in vivo biosynthesis of aromatic polyketides derived from non-acetate primer units. Here we have studied the role of ZhuC using PKS proteins reconstituted in vitro. We show that the tetracenomycin (tcm) minimal PKS can be directly primed with non-acetate acyl groups. In the presence of ∼10 μM hexanoyl-ZhuG or ∼100 μM hexanoyl-CoA, the tcm minimal PKS synthesized hexanoyl-primed analogues of octaketides SEK4 and SEK4b, as well as acetate-primed decaketides SEK15 and SEK15b at comparable levels. Addition of ZhuC abolished synthesis of the acetate-primed decaketides, resulting in exclusive synthesis of the hexanoyl-primed octaketides. In the absence of alternative acyl donors, ZhuC severely retarded the activity of the tcm minimal PKS. The editing capabilities of ZhuC were directly revealed by demonstrating that ZhuC has 100 times greater specificity for acetyl- and propionyl-ACP as compared to hexanoyl- and octanoyl-ACP. Thus, by purging the acetate primer units that otherwise dominate polyketide chain initiation, ZhuC (and presumably its homologues in other PKSs such as the doxorubicin and frenolicin PKSs) allows alternative primer units to be utilized by the elongation module in vivo. The abilities of other alkylacyl primer units to prime the tcm minimal PKS were also investigated in this report.

UR - http://www.scopus.com/inward/record.url?scp=3242738305&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=3242738305&partnerID=8YFLogxK

U2 - 10.1021/bi049157k

DO - 10.1021/bi049157k

M3 - Article

C2 - 15260498

AN - SCOPUS:3242738305

VL - 43

SP - 9546

EP - 9555

JO - Biochemistry

JF - Biochemistry

SN - 0006-2960

IS - 29

ER -