6z1e
From Proteopedia
Crystal structure of the AAA domain of Rubisco Activase from Nostoc sp. (strain PCC 7120)
Structural highlights
FunctionRCA_NOSS1 Activation of RuBisCO (ribulose-1,5-bisohosphate carboxylase/oxygenase; EC 4.1.1.39) involves the ATP-dependent carboxylation of the epsilon-amino group of lysine leading to a carbamate structure. Publication Abstract from PubMedRubisco, the key enzyme of CO(2) fixation in photosynthesis, is prone to inactivation by inhibitory sugar phosphates. Inhibited Rubisco undergoes conformational repair by the hexameric AAA+ chaperone Rubisco activase (Rca) in a process that is not well understood. Here, we performed a structural and mechanistic analysis of cyanobacterial Rca, a close homolog of plant Rca. In the Rca:Rubisco complex, Rca is positioned over the Rubisco catalytic site under repair and pulls the N-terminal tail of the large Rubisco subunit (RbcL) into the hexamer pore. Simultaneous displacement of the C terminus of the adjacent RbcL opens the catalytic site for inhibitor release. An alternative interaction of Rca with Rubisco is mediated by C-terminal domains that resemble the small Rubisco subunit. These domains, together with the N-terminal AAA+ hexamer, ensure that Rca is packaged with Rubisco into carboxysomes. The cyanobacterial Rca is a dual-purpose protein with functions in Rubisco repair and carboxysome organization. Dual Functions of a Rubisco Activase in Metabolic Repair and Recruitment to Carboxysomes.,Flecken M, Wang H, Popilka L, Hartl FU, Bracher A, Hayer-Hartl M Cell. 2020 Oct 15;183(2):457-473.e20. doi: 10.1016/j.cell.2020.09.010. Epub 2020 , Sep 25. PMID:32979320[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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