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 -.

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)


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].

Simon et al. BMC Plant Biology 2006 6:2   doi:10.1186/1471-2229-6-2

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