Affordable Access

deepdyve-link
Publisher Website

A detailed biochemical characterization of phosphopantothenate synthetase, a novel enzyme involved in coenzyme A biosynthesis in the Archaea.

Authors
  • Ishibashi, Takuya
  • Tomita, Hiroya
  • Yokooji, Yuusuke
  • Morikita, Tatsuya
  • Watanabe, Bunta
  • Hiratake, Jun
  • Kishimoto, Asako
  • Kita, Akiko
  • Miki, Kunio
  • Imanaka, Tadayuki
  • Atomi, Haruyuki
Type
Published Article
Journal
Extremophiles
Publisher
Springer-Verlag
Publication Date
Nov 01, 2012
Volume
16
Issue
6
Pages
819–828
Identifiers
DOI: 10.1007/s00792-012-0477-5
PMID: 22940806
Source
Medline
License
Unknown

Abstract

We have previously reported that the majority of the archaea utilize a novel pathway for coenzyme A biosynthesis (CoA). Bacteria/eukaryotes commonly use pantothenate synthetase and pantothenate kinase to convert pantoate to 4'-phosphopantothenate. However, in the hyperthermophilic archaeon Thermococcus kodakarensis, two novel enzymes specific to the archaea, pantoate kinase and phosphopantothenate synthetase, are responsible for this conversion. Here, we examined the enzymatic properties of the archaeal phosphopantothenate synthetase, which catalyzes the ATP-dependent condensation of 4-phosphopantoate and β-alanine. The activation energy of the phosphopantothenate synthetase reaction was 82.3 kJ mol(-1). In terms of substrate specificity toward nucleoside triphosphates, the enzyme displayed a strict preference for ATP. Among several amine substrates, activity was detected with β-alanine, but not with γ-aminobutyrate, glycine nor aspartate. The phosphopantothenate synthetase reaction followed Michaelis-Menten kinetics toward β-alanine, whereas substrate inhibition was observed with 4-phosphopantoate and ATP. Feedback inhibition by CoA/acetyl-CoA and product inhibition by 4'-phosphopantothenate were not observed. By contrast, the other archaeal enzyme pantoate kinase displayed product inhibition by 4-phosphopantoate in a non-competitive manner. Based on our results, we discuss the regulation of CoA biosynthesis in the archaea.

Report this publication

Statistics

Seen <100 times