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

ABSTRACT: 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 CO2 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

SUBMITTER: Jensen E 

PROVIDER: S-EPMC5516110 | biostudies-literature | 2017 Sep

REPOSITORIES: biostudies-literature