Epimerase and Reductase Activities of Polyketide Synthase Ketoreductase Domains Utilize the Same Conserved Tyrosine and Serine Residues

The role of the conserved active site tyrosine and serine residues in epimerization catalyzed by polyketide synthase ketoreductase (PKS KR) domains has been investigated. Both mutant and wild-type forms of epimerase-active KR domains, including the intrinsically redox-inactive EryKR3° and PicKR3° as well as redox-inactive mutants of EryKR1, were incubated with [2-(2)H]-(2R,3S)-2-methyl-3-hydroxypentanoyl-SACP ([2-(2)H]-2) and 0.05 equiv of NADP(+) in the presence of the redox-active, epimerase-inactive EryKR6 domain. The residual epimerase activity of each mutant was determined by tandem equilibrium isotope exchange, in which the first-order, time-dependent washout of isotope from 2 was monitored by liquid chromatography-tandem mass spectrometry with quantitation of the deuterium content of the diagnostic pantetheinate ejection fragment (4). Replacement of the active site Tyr or Ser residues, alone or together, significantly reduced the observed epimerase activity of each KR domain with minimal effect on substrate binding. Our results demonstrate that the epimerase and reductase activities of PKS KR domains share a common active site, with both reactions utilizing the same pair of Tyr and Ser residues..

Medienart:

Artikel

Erscheinungsjahr:

2016

Erschienen:

2016

Enthalten in:

Zur Gesamtaufnahme - volume:55

Enthalten in:

Biochemistry - 55(2016), 8, Seite 1179

Sprache:

Englisch

Beteiligte Personen:

Xie, Xinqiang [VerfasserIn]
Garg, Ashish [Sonstige Person]
Keatinge-Clay, Adrian T [Sonstige Person]
Khosla, Chaitan [Sonstige Person]
Cane, David E [Sonstige Person]

Links:

www.ncbi.nlm.nih.gov

BKL:

35.70

Themen:

Catalysis
Chemical properties
Liquid chromatography
Mass spectrometry
Oxidation-reduction reaction
Polyketides
Research
Usage

RVK:

RVK Klassifikation

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

OLC1972564560