Enzyme Co-Localization with Rubisco in Pea Leaf Chloroplasts

Abstract

Immunocytolocalization experiments indicate that carbonic anhydrase, phosphoribulokinase, and P-glycerate kinase are near neighbors of Rubisco in the pea leaf chloroplast stroma. Direct transfer of ribulose bisphosphate and gaseous CO(2) from phosphoribulokinase and carbonic anhydrase to Rubisco, and direct transfer of P-glycerate from Rubisco to P-glycerate kinase in the chloroplast stroma, is then a possibility. Rubisco activase, responsible for the removal of inhibitory sugar phosphates that bind to the active site of Rubisco in the dark, also appears to be co-localized with Rubisco.

Loss of the Transit Peptide and an Increase in Gene Expression of an Ancestral Chloroplastic Carbonic Anhydrase Were Instrumental in the Evolution of the Cytosolic C4 Carbonic Anhydrase in Flaveria

“…Modeling studies (Cowan, 1986), a decrease in carbon isotope discrimination in transgenic tobacco (Nicotiana tabacum) plants with severely reduced CA activity (Price et al, 1994;Williams et al, 1996), the coelution of b-CA and Rubisco, along with other enzymes of the photosynthetic carbon reduction cycle, in multienzyme complexes (Jebanathirajah and Coleman, 1998), and the colocalization of b-CA and Rubisco in sections of pea chloroplasts (Anderson and Carol, 2004) are consistent with this hypothesis. The lack of a significant effect on CO 2 assimilation when CA activity was reduced using antisense and gene knockout technologies (Majeau et al, 1994;Price et al, 1994;Ferreira et al, 2008), except during early seedling development in Arabidopsis (Ferreira et al, 2008), however, argues against chloroplastic b-CA in C 3 plants having a major role in photosynthesis.…”

Responses of gas exchange, cellular membrane integrity, and antioxidant enzymes activities of salinity-stressed winter wheat to ozone pollution

“…In saline condition, no significant differences were measured in C i between CF and +O 3 plants, indicating plant organs has adapted to the stress. Anderson and Carol (2004) reported that Rubisco makes up as much as 70% of the soluble protein in the chloroplast. Therefore, O 3 -induced reduction in soluble protein may result from the loss of Rubisco content and activity, which further decline photosynthesis.…”

A 160 kDa protein with carbonic anhydrase activity is complexed with rubisco on the outer surface of thylakoids

“…Awareness that several Calvin cycle enzymes in higher plants appear to be assembled into stable multienzyme complexes has provoked significant interest in recent years (Süss and Sainis, 1997;Anderson et al, 1996: Jebanathirajah andColeman, 1998;Babadzhanova et al, 2002;Anderson and Carol, 2004,). The association of specific enzymes in protein complexes is presumed to facilitate channeling of pathway intermediates from one enzyme active site to another (Jebanathirajah and Coleman, 1998).…”

“…The association of specific enzymes in protein complexes is presumed to facilitate channeling of pathway intermediates from one enzyme active site to another (Jebanathirajah and Coleman, 1998). These complexes are not simple artifacts resulting from fortuitous protein associations in vitro, but rather represent functioning complexes that facilitate photosynthetic CO 2 fixation in the chloroplast (Anderson and Carol, 2004). They are also certainly responsible, in part, for the very short initial lag period in photosynthetic CO 2 fixation by allowing the Calvin cycle to operate with low levels of intermediates.…”

“…Later, Jebanathirajah and Coleman (1998) showed that a portion of the chloroplast CA is associated with the periphery of the Calvin cycle complex, possibly in some configuration with rubisco. Anderson and Carol (2004) established that rubisco forms stable complexes with several other enzymes, including the enzymes that provide its substrates: CA and phosphoribulokinase. They presented evidence showing that rubisco activase, CA, phosphoribulokinase, and 3-P-glycerate kinase, which catalyzes the next reaction in the Calvin cycle, are co-localized with rubisco in situ.…”