Regulation of the Calvin-Benson-Bassham cycle in the enigmatic diatoms: biochemical and evolutionary variations on an original theme.

Autor: Jensen E; Aix Marseille Univ CNRS, BIP UMR 7281, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France., Clément R; Aix Marseille Univ CNRS, BIP UMR 7281, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France., Maberly SC; Lake Ecosystems Group, Centre for Ecology and Hydrology, Lancaster Environment Centre, Library Avenue, Bailrigg, Lancaster LA1 4AP, UK., Gontero B; Aix Marseille Univ CNRS, BIP UMR 7281, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France bmeunier@imm.cnrs.fr.
Jazyk: angličtina
Zdroj: Philosophical transactions of the Royal Society of London. Series B, Biological sciences [Philos Trans R Soc Lond B Biol Sci] 2017 Sep 05; Vol. 372 (1728).
DOI: 10.1098/rstb.2016.0401
Abstrakt: In Plantae, the Calvin-Benson-Bassham (CBB) cycle is highly regulated and most of its enzymes have been thoroughly studied. Since diatoms arose as a result of secondary endosymbiosis with one or more Plantae ancestors, their precise evolutionary history is enigmatic and complex resulting in biochemical variations on the original CBB cycle theme. The Rubisco Michaelis constant for CO 2 is higher in diatoms than land plants and the nuclear-encoded Rubisco activase in Plantae is replaced by an analogous chloroplast-encoded CbbX (Calvin-Benson-Bassham protein X) in diatoms. In the CBB cycle reduction phase, phosphoglycerate kinase in diatoms is redox-regulated and similar to that in red algae; however, glyceraldehyde phosphate dehydrogenase (GAPDH) is not redox-regulated, unlike in Plantae. The phosphoribulokinase (PRK)-GAPDH-CP12 complex found in many photosynthetic organisms has not yet been found in diatoms, but a ferredoxin-NADP reductase (FNR)-GAPDH-CP12 complex has been found in one species. In the CBB cycle regeneration phase, sedoheptulose 1,7-bisphosphatase and PRK are not redox-regulated in diatoms, unlike in Plantae. Regulation at the transcriptional level seems to be important in diatoms. CBB cycle enzyme properties appear to be variable among diatoms, but this view relies on results from a few model species: a greater range of diatoms need to be studied to test this.This article is part of the themed issue 'The peculiar carbon metabolism in diatoms'.
(© 2017 The Author(s).)
Databáze: MEDLINE
Externí odkaz: