Figure 1.

Comparison of CbbX and RCA. CbbX monomer from P. tricornutum (a) is compared with RCA from A. thaliana (PDB: 4W5 W; (b)). Important residues are identified and highlighted. Residues are numbered according to P. tricornutum and A. thaliana respective sequences. The ‘P-loop’ (Walker-A) is also shown (in red) in both models. In CbbX, key amino acids for RuBP and nucleotide binding sites were predicted according to the R. sphaeroides model [50,51]. Residues K313 and V316 in RCA are involved in RCA-Rubisco specificity [49,52]. Residues involved in RCA ATP binding site—K113 [52,53], G112, G107 [54]—and ATP hydrolysis—K293 [52]—are shown. A redox-regulated region (see [49]) is also identified, although part of the C-terminus is missing in the representation. Phaeodactylum tricornutum CbbX was modelled using SWISS MODEL webtool and R. sphaeroides CbbX crystal structure (PDB: 3SYL) as template. Ribbon representations were produced with PyMol software.