M Miyake1, K Kataoka, M Shirai, Y Asada. 1. National Institute of Bioscience and Human-Technology, Agency of Industrial Science and Technology, Tsukuba, Ibaraki, Japan.
Abstract
Poly-beta-hydroxybutyrate (PHB) synthesis in a cyanobacterium, Synechococcus sp. strain MA19, is controlled at the enzyme level and is dependent on the C/N balance in the culture medium. The control involves at least two enzymes. The first enzyme is PHB synthase. Little PHB synthase activity was detected in crude extracts from cells grown under nitrogen-sufficient conditions (MA19(+N)). The activity was detected exclusively in membrane fractions from nitrogen-deprived cells (MA19(-N)) under light but not dark conditions. The shift in the enzyme activity was insensitive to chloramphenicol, which suggests posttranslational activation. Acetyl phosphate activated PHB synthase in membrane fractions from MA19(+N). In vitro, the activation level of PHB synthase changed, depending on the concentration of acetyl phosphate. The second enzyme was phosphotransacetylase (EC 2.3.1.8), which catalyzes the conversion of acetyl coenzyme A (acetyl-CoA) to acetyl phosphate. The activity was detected in crude extracts from MA19(-N) but not in those from MA19(+N). The results suggested that intracellular acetyl phosphate concentration could be controlled, depending on C/N balance and intracellular acetyl-CoA concentration. Acetyl phosphate probably acts as a signal of C/N balance affecting PHB metabolism in MA19.
Poly-beta-hydroxybutyrate (n class="Chemical">PHB) synthesis in a cyanobacterium, Synechococcus sp. strain MA19, is controlled at the enzyme level and is dependent on the C/N balance in the culture medium. The control involves at least two enzymes. The first enzyme is PHB synthase. Little PHB synthase activity was detected in crude extracts from cells grown under nitrogen-sufficient conditions (MA19(+N)). The activity was detected exclusively in membrane fractions from nitrogen-deprived cells (MA19(-N)) under light but not dark conditions. The shift in the enzyme activity was insensitive to chloramphenicol, which suggests posttranslational activation. Acetyl phosphate activated PHB synthase in membrane fractions from MA19(+N). In vitro, the activation level of PHB synthase changed, depending on the concentration of acetyl phosphate. The second enzyme was phosphotransacetylase (EC 2.3.1.8), which catalyzes the conversion of acetyl coenzyme A (acetyl-CoA) to acetyl phosphate. The activity was detected in crude extracts from MA19(-N) but not in those from MA19(+N). The results suggested that intracellular acetyl phosphate concentration could be controlled, depending on C/N balance and intracellular acetyl-CoA concentration. Acetyl phosphate probably acts as a signal of C/N balance affecting PHB metabolism in MA19.
Authors: T U Gerngross; K D Snell; O P Peoples; A J Sinskey; E Csuhai; S Masamune; J Stubbe Journal: Biochemistry Date: 1994-08-09 Impact factor: 3.162
Authors: Maria A Trainer; David Capstick; Alicja Zachertowska; Kathy N Lam; Scott R D Clark; Trevor C Charles Journal: BMC Microbiol Date: 2010-03-27 Impact factor: 3.605
Authors: Anastasia A Pantazaki; Maria G Tambaka; Valerie Langlois; Philippe Guerin; Dimitrios A Kyriakidis Journal: Mol Cell Biochem Date: 2003-12 Impact factor: 3.396