[RBL_SYNP6] RuBisCO catalyzes two reactions: the carboxylation of D-ribulose 1,5-bisphosphate, the primary event in carbon dioxide fixation, as well as the oxidative fragmentation of the pentose substrate in the photorespiration process. Both reactions occur simultaneously and in competition at the same active site.[HAMAP-Rule:MF_01338]
Publication Abstract from PubMed
The form I Rubisco of autotrophic bacteria, algae and plants is a complex of eight large (RbcL) and eight small (RbcS) subunits. It fixes atmospheric CO(2) in the dark reaction of photosynthesis. As shown for the cyanobacterial enzyme, folding of the RbcL subunits is mediated by the GroEL-GroES chaperonin system, and assembly requires the specialized chaperone RbcX, a homodimer of ~15-kDa subunits. Here we present the 3.2-A crystal structure of a Rubisco assembly intermediate, consisting of the RbcL(8) core with eight RbcX(2) molecules bound. The structure reveals the molecular mechanism by which RbcX(2) mediates oligomeric assembly. Specifically, RbcX(2) provides positional information for proper formation of antiparallel RbcL dimers, thereby preventing RbcL-RbcL misalignment and off-pathway aggregation. The RbcL(8)(RbcX(2))(8) structure also suggests that RbcS functions by stabilizing the '60s loop' of RbcL in the catalytically active conformation.
Crystal structure of a chaperone-bound assembly intermediate of form I Rubisco.,Bracher A, Starling-Windhof A, Hartl FU, Hayer-Hartl M Nat Struct Mol Biol. 2011 Jul 17. doi: 10.1038/nsmb.2090. PMID:21765418
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
↑ Bracher A, Starling-Windhof A, Hartl FU, Hayer-Hartl M. Crystal structure of a chaperone-bound assembly intermediate of form I Rubisco. Nat Struct Mol Biol. 2011 Jul 17. doi: 10.1038/nsmb.2090. PMID:21765418 doi:10.1038/nsmb.2090