The Calvin-Benson-Bassham (CBB) cycle is in charge of CO2 assimilation and carbohydrate creation in oxyphototrophs. PSI upon lighting through ferredoxin as well as the ferredoxin thioredoxin reductase program (Buchanan, 1991; Dai et al., 2004) and additional decrease and activate the enzymes from the CBB routine, including phosphoribulokinase (PRK) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH; Miginiac-Maslow and Ruelland, 1999; Jacquot and Schurmann, 2000; Balmer and Buchanan, 2005; Buchanan and Schrmann, 2008; Michelet et al., 2013). Furthermore, the tiny chloroplast proteins CP12 (Pohlmeyer et al., 1996), which can be central for the rules from the CBB routine and generally possesses two Cys pairs at both N- and C-terminal areas, can be redox-regulated by TRXs (Wedel et al., 1997; Howard et al., 2008; Lpez-Calcagno et al., 2014). PRK catalyzes the ATP-dependent phosphorylation of ribulose-5-phosphate (Ru5P) to create ribulose-1,5-bisphosphate, which is necessary for Rubisco-dependent CO2 fixation (Avron and Gibbs, 1974), due to that your CBB routine is set up. The PRK structure and catalytic mechanism were previously studied in an anoxygenic bacterium, (RsPRK; Harrison et al., 1998; Kung et al., 1999). However, PRK from oxygenic phototrophs differs significantly from RsPRK in primary sequence, oligomeric state, and regulatory mechanism (Buchanan, 1980; GW-786034 kinase activity assay Tabita, 1980). In contrast to the octameric RsPRK, PRKs from oxygenic phototrophs are commonly presented as homodimers, and each monomer contains a pair of Cys residues at the N-terminal region. PRKs from plants and eukaryotic algae are redox-regulated through reversible reduction and oxidation of this Cys pair (Latzko et al., 1970; Wirtz et al., 1982; Milanez et al., 1991; Brandes et al., 1996), which is absent in RsPRK. Reduced PRK represents its active state, while the oxidized form is inactive, although a previous report suggested that the latter form exhibits basal activity (Marri et al., 2005). Cyanobacterial PRKs also contain a similar Cys pair at the N-terminal region; however, earlier studies suggested that in vivo, cyanobacterial PRK is more resistant than plant PRK to oxidative inactivation (Tamoi et al., 1998; Kobayashi et al., 2003). Sequence alignment results revealed that cyanobacterial PRKs lack GW-786034 kinase activity assay the loop between the two Cys residues in plant-type PRKs (termed the clamp loop), which is GW-786034 kinase activity assay considered to participate in TRX binding (Gurrieri et al., Ocln 2019). The architecture of the dimeric PRK had not been determined until the crystal structure of PRK from the archaeon (MhPRK) was reported (Kono et al., 2017). However, MhPRK lacks the Cys pair and is not subject to redox regulation. Recently, the structures of oxidized PRK from the cyanobacterium sp strain PCC6301 and of reduced PRK from Arabidopsis (were solved (Gurrieri et al., 2019; Wilson et al., 2019). These structural data revealed the dimerization pattern of photosynthetic PRK and confirmed that the two Cys residues involved in redox regulation are positioned apart in the reduced PRK while forming a disulfide bond in the oxidized form. As one of the Cys residues is located in the P-loop region, which usually functions in ATP binding, these findings suggested that disruption of its ATP binding site results in the inactivation of oxidized PRK (Wilson et al., 2019). GAPDH catalyzes the conversion of d-glycerate 1,3-bisphosphate to glyceraldehyde 3-phosphate in the presence of NADPH (Melandri et al., 1968). Two types of GAPDH, namely GapA and GapB, are present in plant chloroplasts, and they give rise to A4- and A2B2-type enzymes (Brinkmann et al., 1989; Scagliarini et al., 1998; Petersen et al., 2006). Most algae usually do not consist of GapB, as well as GW-786034 kinase activity assay the A4 type may be the major type of GAPDH in eukaryotic algae and cyanobacteria (Petersen et al., 2006). GapB is nearly similar to GapA but comes with an extra C-terminal expansion (CTE) that bears a set of Cys residues targeted by TRXs (Baalmann et al., 1996; Petersen et al., 2006)..