2af8
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ACTINORHODIN POLYKETIDE SYNTHASE ACYL CARRIER PROTEIN FROM STREPTOMYCES COELICOLOR A3(2), NMR, MINIMIZED AVERAGE STRUCTURE
OverviewOverview
The solution structure of the actinorhodin acyl carrier protein (act, apo-ACP) from the polyketide synthase (PKS) of Streptomyces coelicolor, A3(2) has been determined using 1H NMR spectroscopy, representing the, first polyketide synthase component for which detailed structural, information has been obtained. Twenty-four structures were generated by, simulated annealing, employing 699 distance restraints and 94 dihedral, angle restraints. The structure is composed, principally, of three major, helices (1, 2, and 4), a shorter helix (3) and a large loop region, separating helices 1 and 2. The structure is well-defined, except for a, portion of the loop region (residues 18-29), the N-terminus (1-4), and a, short stretch (57-61) in the loop connecting helices 2 and 3. The RMS, distribution of the 24 structures about the average structure is 1.47 A, for backbone atoms, 1.84 A for all heavy atoms (residues 5-86), and 1.01 A, for backbone atoms over the helical regions (5-18, 41-86). The tertiary, fold of act apo-ACP shows a strong structural homology with Escherichia, coli fatty acid synthase (FAS) ACP, though some structural differences, exist. First, there is no evidence that act apo-ACP is conformationally, averaged between two or more states as observed in E. coli FAS ACP., Second, act apo-ACP shows a disordered N-terminus (residues 1-4) and a, longer flexible loop (19-41 with 19-29 disordered) as opposed to E. coli, FAS ACP where the N-terminal helix starts at residue 3 and the loop region, is three amino acids shorter (16-35). Most importantly, however, although, the act apo-ACP structure contains a hydrophobic core, there are in, addition a number of buried hydrophilic groups, principally Arg72 and, Asn79, both of which are 100% conserved in the PKS ACPs and not the FAS, ACPs and may therefore play a role in stabilizing the growing polyketide, chain. The structure-function relationship of act ACP is discussed in the, light of these structural data and recent genetic advances in the field.
About this StructureAbout this Structure
2AF8 is a Single protein structure of sequence from Streptomyces coelicolor. Structure known Active Site: S42. Full crystallographic information is available from OCA.
ReferenceReference
Solution structure of the actinorhodin polyketide synthase acyl carrier protein from Streptomyces coelicolor A3(2)., Crump MP, Crosby J, Dempsey CE, Parkinson JA, Murray M, Hopwood DA, Simpson TJ, Biochemistry. 1997 May 20;36(20):6000-8. PMID:9166770
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