Sterigmatocystin biosynthesis in Aspergillus nidulans requires a novel type I polyketide synthase

Yu, Jae Hyuk; Leonard, Tom

doi:10.1128/jb.177.16.4792-4800.1995

Cited by 153 publications

(113 citation statements)

References 70 publications

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“…In addition to the biosynthetically related metabolites sterigmatocystin (8) (34) and dothistromin (9) (35), which clearly have a C 6 fatty acid starter unit, other PKS starter units are known. For example, in the synthesis of 1,3,6,8-tetrahydroxynaphthalene (10), where the starter unit is not obvious in the final product, malonyl-CoA has been demonstrated in vitro to be the starter unit as well as the extender unit (36).…”

Section: Discussionmentioning

confidence: 99%

Identification of a starter unit acyl-carrier protein transacylase domain in an iterative type I polyketide synthase

Crawford

Dancy

Hill

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

168

184

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Polyketides are a class of natural products that exhibit a wide range of functional and structural diversity. They include antibiotics, immunosuppressants, antifungals, antihypercholesterolemics, and cytotoxins. Polyketide synthases (PKSs) use chemistry similar to fatty acid synthases (FASs), although building block variation and differing extents of reduction of the growing polyketide chain underlie their biosynthetic versatility. In contrast to the well studied sequential modular type I PKSs, less is known about how the iterative type I PKSs carry out and control chain initiation, elongation, folding, and cyclization during polyketide processing. Domain structure analysis of a group of related fungal, nonreducing PKSs has revealed well defined N-terminal domains longer than commonly seen for FASs and modular PKSs. Predicted structure of this domain disclosed a region similar to malonyl-CoA:acyl-carrier protein (ACP) transacylases (MATs). MATs play a key role transferring precursor CoA thioesters from solution onto FASs and PKSs for chain elongation. On the basis of site-directed mutagenesis, radiolabeling, and kinetics experiments carried out with individual domains of the norsolorinic acid PKS, we propose that the Nterminal domain is a starter unit:ACP transacylase (SAT domain) that selects a C6 fatty acid from a dedicated yeast-like FAS and transfers this unit onto the PKS ACP, leading to the production of the aflatoxin precursor, norsolorinic acid. These findings could indicate a much broader role for SAT domains in starter unit selection among nonreducing iterative, fungal PKSs, and they provide a biochemical rationale for the classical acetyl ''starter unit effect.'' aflatoxin biosynthesis ͉ fatty acid synthase

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Section: Discussionmentioning

confidence: 99%

Identification of a starter unit acyl-carrier protein transacylase domain in an iterative type I polyketide synthase

Crawford

Dancy

Hill

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

168

184

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“…Therefore, in the generation process of the lkc-PKS genes, the KS gene was fused with other genes in a unique order, while the AT and DH genes were not fused and remained as separate genes. The tandem alignment of two ACP domains was also found in the albicidin PKS [18] and several fungal type-I PKSs, for example, WA for naphtopyrone [19,20] and StcA for sterigmatocystin [21]. Huang et al [18] proposed that the second ACP domain in the albicidin PKS serves as a waiting position for growing chains to facilitate iterative condensation, although no experimental evidence was provided.…”

Section: Lkcf-lkcg Fusant Produced Lankacidin At a Similar Level To Tmentioning

confidence: 99%

“…Huang et al [18] proposed that the second ACP domain in the albicidin PKS serves as a waiting position for growing chains to facilitate iterative condensation, although no experimental evidence was provided. Fujii et al [21] disrupted each of the two tandem ACP domains in WA and showed that either ACP alone was enough for naphtopyrone synthesis. It is noteworthy that tandemly aligned doublet and triplet ACP domains were found even in the modular PKSs for mupirocin in Pseudomonas fluorescens [22].…”

Section: Lkcf-lkcg Fusant Produced Lankacidin At a Similar Level To Tmentioning

confidence: 99%

Analysis of Modular-iterative Mixed Biosynthesis of Lankacidin by Heterologous Expression and Gene Fusion

2007

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Lankacidin is a unique 17-membered macrocyclic antibiotic different from usual even-membered macrolides. Based on the gene organization of the lankacidin biosynthetic cluster coded on the linear plasmid pSLA2-L in Streptomyces rochei, we previously proposed a hypothesis of modular-iterative mixed polyketide biosynthesis for lankacidin. Two experimental evidences in this paper further strengthened this hypothesis. Heterologous expression of the lankacidin cluster (lkcAlkcO) in Streptomyces lividans resulted in lankacidinol A production, indicating that the gene cluster is sufficient for the synthesis of the lankacidin skeleton. In addition, a gene fusant of lkcF and lkcG produced lankacidin at a similar level to the parent strain, suggesting that an iterative function of the LkcF protein is unlikely. These results are consistent with the hypothesis that LkcC is used four times and LkcA, LkcF and LkcG are used modularly to accomplish eight condensation reactions leading to the lankacidin skeleton.

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“…Recent evidence from the Steinbüchel laboratory has been interpreted to indicate that in vitro there are 25 polymer chains synthesized per molecule of C. Vinosum PHA synthase, which implies that there is a termination step (29). In animal fatty acid synthase and in some members of the polyketide synthase family, a thioesterase domain containing an essential serine is required for the hydrolysis step or lactone formation (30)(31)(32)(33). Thus, an alternative role for the conserved serine in PHA synthases might be controlling the chain length in a fashion that remains to be established.…”

mentioning

confidence: 99%

PHA Synthase from Chromatium vinosum: Cysteine 149 Is Involved in Covalent Catalysis

et al. 1998

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Polyhydroxyalkanoate synthase (PHA) from Chromatium Vinosum catalyzes the conversion of 3-hydroxybutyryl-CoA (HB-CoA) to polyhydroxybutyrate (PHB) and CoA. The synthase is composed of a ∼1:1 mixture of two subunits, PhaC and PhaE. Size-exclusion chromatography indicates that in solution PhaC and PhaE exist as large molecular weight aggregates. The holo-enzyme, PhaEC, has a specific activity of 150 units/mg. Each subunit was cloned, expressed, and purified as a (His) 6 -tagged construct. The PhaC-(His) 6 protein catalyzed polymerization with a specific activity of 0.9 unit/mg; the PhaE-(His) 6 protein was inactive (specific activity <0.001 unit/mg). Addition of PhaE-(His) 6 to PhaC-(His) 6 increased the activity several 100-fold. To investigate the priming step of the polymerization process, the PhaEC was incubated with a trimer of HB-CoA in which the terminal hydroxyl was replaced with tritium ( Sequencing by ion trap mass spectrometry showed that they were identical and that they each contained an altered cysteine (C149). One peptide contained the [ 3 H]-sT while the other two contained, in addition to the [ 3 H]-sT, one and two additional monomeric HBs, respectively. Mutation of C149 to alanine gave inactive synthase. The remaining two cysteines of PhaC, 292 and 130, were also mutated to alanine. The former had wild-type (wt) activity, while the latter had 0.004 wt % activity and was capable of making polymer. A mechanism is proposed in which PhaC contains all the elements essential for catalysis and the polymerization proceeds by covalent catalysis using C149 and potentially C130.Polyhydroxyalkanoates (PHAs 1 ) are polyoxoesters with properties that range from elastomers to thermoplastics (1-4). They are produced by a wide range of bacteria when they are placed in an environment of nutrient limitation (5). Copolymers of polyhydroxybutyrate (PHB) and polyhydroxyvalerate in the correct ratio have properties similar to the petrochemically based polypropylenes, the major component of bulk plastics (6). In 1997, the US market for thermoplastics was on the order of 40 million tons per year (7). PHAs have recently received much attention because they are biodegradable and can be generated from biorenewable sources: bacteria and plants (8). The major focus of many investigators is to make their production economically competitive with the polypropylenes. To achieve this goal, the requirements for the polymerization process need to be established. This paper focuses on the PHA synthase from Chromatium Vinosum which catalyzes the formation of PHB from 3-hydroxybutyryl-CoA (HB-CoA). Evidence is presented that two cysteines and covalent catalysis play an important role in the initiation and elongation of the polymerization process.PHA synthases from 20 organisms have now been identified. They have been divided into three classes based on their substrate specificity and subunit composition (9). The class I synthases, with the Ralstonia eutropha synthase as a prototype, are composed of a single polypeptide (∼65 k...

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Sterigmatocystin biosynthesis in Aspergillus nidulans requires a novel type I polyketide synthase

Cited by 153 publications

References 70 publications

Identification of a starter unit acyl-carrier protein transacylase domain in an iterative type I polyketide synthase

Identification of a starter unit acyl-carrier protein transacylase domain in an iterative type I polyketide synthase

Analysis of Modular-iterative Mixed Biosynthesis of Lankacidin by Heterologous Expression and Gene Fusion

PHA Synthase from Chromatium vinosum: Cysteine 149 Is Involved in Covalent Catalysis

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