Catalogo Articoli (Spogli Riviste)

OPAC HELP

Titolo:
Mechanisms of molecular recognition in the pikromycin polyketide synthase
Autore:
Chen, S; Xue, YQ; Sherman, DH; Reynolds, KA;
Indirizzi:
Virginia Commonwealth Univ, Dept Med Chem, Richmond, VA 23219 USA VirginiaCommonwealth Univ Richmond VA USA 23219 , Richmond, VA 23219 USA Virginia Commonwealth Univ, Inst Struct Biol & Drug Discovery, Richmond, VA 23219 USA Virginia Commonwealth Univ Richmond VA USA 23219 , Richmond, VA 23219 USA Univ Minnesota, Dept Microbiol, Biol Proc Technol Inst, Minneapolis, MN 55455 USA Univ Minnesota Minneapolis MN USA 55455 l Inst, Minneapolis, MN 55455 USA
Titolo Testata:
CHEMISTRY & BIOLOGY
fascicolo: 12, volume: 7, anno: 2000,
pagine: 907 - 918
SICI:
1074-5521(200012)7:12<907:MOMRIT>2.0.ZU;2-X
Fonte:
ISI
Lingua:
ENG
Soggetto:
BIOSYNTHETIC GENE-CLUSTER; STREPTOMYCES-VENEZUELAE; ERYTHROMYCIN; RAPAMYCIN; DOMAINS; ORGANIZATION; SPECIFICITY; MACROLIDE;
Keywords:
molecular recognition; pikromycin; polyketide synthase; Streptomyces venezuelae;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
25
Recensione:
Indirizzi per estratti:
Indirizzo: Reynolds, KA Virginia Commonwealth Univ, Dept Med Chem, 800 E Leigh St, Richmond, VA 23219 USA Virginia Commonwealth Univ 800 E Leigh St Richmond VA USA 23219
Citazione:
S. Chen et al., "Mechanisms of molecular recognition in the pikromycin polyketide synthase", CHEM BIOL, 7(12), 2000, pp. 907-918

Abstract

Background: Modular polyketide synthases (PKSs) produce a wide range of medically significant compounds. In the case of the pikromycin PKS of Streptomyces venezuelae, four separate polypeptides (PikAl-PikAIV), comprising a total of one loading domain and six extension modules, generate the 14-membered ring macrolactone narbonolide. The polypeptide PikAIV contains a thioesterase (TE) domain and is responsible for catalyzing both the last elongation step with methylmalonyl CoA, and subsequent release of the final polyketide chain elongation intermediate from the PKS. Under certain growth conditions this polypeptide is synthesized from an alternative translational start site, giving rise to an N-terminal truncated form of PikAIV, containing only half of the ketosynthase (KS6) domain. The truncated form of PikAIV is unable to catalyze the final elongation step, but is able to cleave a polyketide chain from the preceding module on PikAIII (ACP(5)), giving rise to the 12-membered ring product 10-deoxymethynolide. Results: S. venezuelae mutants expressing hybrid PikAIV polypeptides containing acyl carrier protein (ACP) and malonyl CoA specific acyltransferase (AT) domains from the rapamycin PKS were unable to catalyze production of 12-or 14-membered ring macrolactone products. Plasmid-based expression of a hybrid PikAIV containing the native KS6 and TE domains, however, restored production of both narbonolide and 10-deoxymethynolide in the S. venezuelae AX912 mutant that generates a TE-deleted form of PikAIV. Use of alternative KS domains or deletion of the KS6 domain within the hybrid PikAIV resulted in loss of both products. Plasmid-based expression of a TE domain of PikAIVas a separate polypeptide in the AX912 mutant resulted in greater than 50%restoration of 10-deoxymethynolide, but not in mutants expressing a hybridPikAIV bearing an unnatural AT domain. Mutants expressing hybrid PikAIV polypeptides containing the natural ATG domains and different ACP domains efficiently produced polyketide products, but with a significantly higher 10-deoxymethynolide/ narbonolide ratio than observed with native PikAIV. Conclusions: Dimerization of KS6 modules allows in vivo formation of a PKSheterodimer using PikAIV polypeptides containing different AT and ACP domains. In such heterodimers, the TE domain and the ATE domain responsible forformation of the narbonolide product are located on different polypeptide chains. The ATG domain of PikAIV plays an important role in facilitating TE-catalyzed chain termination (10-deoxymethynolide formation) at the proceeding module in PikAIII. The pikromycin PKS can tolerate the presence of multiple forms (active and inactive) of PikAIV, and decreased efficiency of elongation by PikAIV can result in increased levels of 10-deoxymethynolide. These results provide new insight into functional molecular interactions and interdomain recognition in modular PKSs.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 03/12/20 alle ore 12:15:20