Evidence for a double-helical structure for modular polyketide synthases

Staunton, James; Caffrey, Patrick; Aparicio, Jesús F.; Roberts, Gareth A.; Bethell, Susanne S.; Leadlay, Peter F.

doi:10.1038/nsb0296-188

Cited by 130 publications

(176 citation statements)

References 27 publications

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“…The radioactivity observed in fragment T6 (which lacks the PCP domain) goes beyond, suggesting that the adenylation domain is catalytically competent even in the absence of its C-terminal region and supporting the assumption that such domain functions in the loading of free ␣-AA (5,15,19). Similar PCP-independent non-covalent substrate binding of an adenylation domain has been reported for the phenylalanine-activating domain of the gramicidin S synthetase, GrsA (41).…”

Section: Discussionsupporting

confidence: 50%

Domain Structure Characterization of the Multifunctional α-Aminoadipate Reductase from Penicillium chrysogenum by Limited Proteolysis

Hijarrubia

Aparicio

Martı́n

2003

Journal of Biological Chemistry

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The ␣-aminoadipate reductase (␣-AAR) of Penicillium chrysogenum, an enzyme that activates the ␣-aminoadipic acid by forming an ␣-aminoadipyl adenylate and reduces the activated intermediate to ␣-aminoadipic semialdehyde, was purified to homogeneity by immunoaffinity techniques, and the kinetics for ␣-aminoadipic acid, ATP, and NADPH were determined. Sequencing of the N-terminal end confirmed the 10 first amino acids deduced from the nucleotide sequence. Its domain structure has been investigated using limited proteolysis and active site labeling. Trypsin and elastase were used to cleave the multienzyme, and the location of fragments within the

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Section: Discussionsupporting

confidence: 50%

Domain Structure Characterization of the Multifunctional α-Aminoadipate Reductase from Penicillium chrysogenum by Limited Proteolysis

Hijarrubia

Aparicio

Martı́n

2003

Journal of Biological Chemistry

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“…The primary fungal FAS subunits are homologous to HexA (Ϸ53% similarity, global alignment) and HexB (Ϸ52% similarity); however, binding to PksA induces a proposed ␣ 2 ␤ 2 ␥ 2 arrangement, quite distinct from the ␣ 6 ␤ 6 organization observed for yeast FAS. On the other hand, mammalian FAS associates as an ␣ 2 head-to-head homodimer with centrally located KS domains, as demonstrated for modular PKSs and hypothesized for PksA (12,30). The unique ␣ 2 ␤ 2 ␥ 2 oligomerization state of NorS must place the SAT domain in a location accessible to both the ACP domain of HexA and the ACP in PksA for efficient transfer and catalysis.…”

Section: Discussionmentioning

confidence: 99%

“…4 MDa as estimated from size-exclusion chromatography (10). Dimerization of PksA is the favored model because of the associative nature of domains within modular type I PKSs (11,12). PksA must accept a C 6 fatty acid starter unit from HexA͞HexB before proceeding to condense seven malonates to create the polyketide backbone 3.…”

mentioning

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.

163

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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“…In modular PKSs, the starter unit is normally provided by a loading domain included at the N terminus of the first multienzyme, as occurs with 6-deoxyerythronolide B synthase 1 (10,35) or the rapamycin synthase RAPS 1 (5). PIMS1, however, lacks any such loading domain, thus making necessary the interaction of module 1 KS either with free acetyl-CoA or, more likely, with a separate loading protein that would present the starter unit to module 1.…”

Section: Discussionmentioning

confidence: 99%

The Biosynthetic Gene Cluster for the 26-Membered Ring Polyene Macrolide Pimaricin

Aparicio¹,

Colina

Ceballos³

et al. 1999

Journal of Biological Chemistry

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The biosynthetic gene cluster for the 26-membered ring of the polyene macrolide pimaricin extends for about 110 kilobase pairs of contiguous DNA in the genome of Streptomyces natalensis. Two sets of polyketide synthase (PKS) genes are separated by a group of small polyketide-functionalizing genes. Two of the polyketide synthase genes, pimS0 and pimS1, have been fully sequenced and disrupted proving the involvement of each of these genes in pimaricin biosynthesis. The pimS0 gene encodes a relatively small acetate-activating PKS (ϳ193 kDa) that appears to work as a loading protein which "presents" the starter unit to the second PKS subunit. The pimS1 gene encodes a giant multienzyme (ϳ710 kDa) harboring 15 activities responsible for the first four cycles of chain elongation in pimaricin biosynthesis, resulting in formation of the polyene chromophore.

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Evidence for a double-helical structure for modular polyketide synthases

Cited by 130 publications

References 27 publications

Domain Structure Characterization of the Multifunctional α-Aminoadipate Reductase from Penicillium chrysogenum by Limited Proteolysis

Domain Structure Characterization of the Multifunctional α-Aminoadipate Reductase from Penicillium chrysogenum by Limited Proteolysis

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

The Biosynthetic Gene Cluster for the 26-Membered Ring Polyene Macrolide Pimaricin

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