Skip to main content

Table 8 Regulation of plastidic enzymes by the thioredoxin system. Proteins similar to embryophyte plastidic thioredoxin-regulated proteins were identified in the genomes of Cyanidioschyzon, Chlamydomonas, and the ESTs of Mesostigma using the BLASTP or BLASTX algorithms. A putative thioredoxin-regulated orthologue as revealed by the conserved cysteine residues is indicated with +. An asterisk indicates putative cyanobacterial/plastidic proteins, which do not contain the conserved cysteines required for thioredoxin-regulation. Missing enzymes are indicated with -.

From: EST analysis of the scaly green flagellate Mesostigma viride (Streptophyta): Implications for the evolution of green plants (Viridiplantae)

  Cyanobacteria Rhodophytes Cyanidioschyzon Chlorophytes Chlamydomonas Mesostigma Embryophytes
PRK + + + + +
SDPase * + + + +
G6PDH * + + n.d. +
FBPase * *1) + + +
γ-ATPase * * + + +
GABDHB - - - + +
NADP-MDH - - +2) n.d. +
Rubisco activase -3) - * * (+)4)
  1. n.d. not detected in Mesostigma. 1) In Galdieria (Cyanidioschyzon) 2 (1) of the 3 conserved cysteines occurring in the Viridiplantae are present [48]. 2) Chlorophyte NADP-malate dehydrogenase possesses a C- and N-terminal extension like the embryophyte enzyme, however only the C-terminal cysteines of the embryophyte enzyme are conserved [49, 50]. 3) A few cyanobacteria contain an unusual rubisco activase. Only the central AAA+ domain shows similarity to plant rubisco activases, whereas the N and C terminal domain are very different [51]. 4) Many angiosperms contain two forms of rubisco activase. Only the long form is regulated by the thioredoxin system [52].