5LT5

Carboxysome shell protein CcmP from Synechococcus elongatus PCC 7942

Summary for 5LT5

• Entry DOI: 10.2210/pdb5lt5/pdb
• Related: 5LSR
• Descriptor: CcmP, GLYCEROL, CHLORIDE ION, ... (4 entities in total)
• Functional Keywords: carboxysome shell protein bmc domain gated transport, transport protein
• Biological source: Synechococcus elongatus PCC 7942
• Total number of polymer chains: 2
• Total formula weight: 48762.93

Authors

Larsson, A.M.,Hasse, D.,Valegard, K.,Andersson, I. (deposition date: 2016-09-06, release date: 2017-04-12, Last modification date: 2024-01-17)

Primary citation

Larsson, A.M.,Hasse, D.,Valegard, K.,Andersson, I.
Crystal structures of beta-carboxysome shell protein CcmP: ligand binding correlates with the closed or open central pore.
J. Exp. Bot., 68:3857-3867, 2017

PubMed Abstract: Cyanobacterial CO2 fixation is promoted by encapsulating and co-localizing the CO2-fixing enzymes within a protein shell, the carboxysome. A key feature of the carboxysome is its ability to control selectively the flux of metabolites in and out of the shell. The β-carboxysome shell protein CcmP has been shown to form a double layer of pseudohexamers with a relatively large central pore (~13 Å diameter), which may allow passage of larger metabolites such as the substrate for CO2 fixation, ribulose 1,5-bisphosphate, through the shell. Here we describe two crystal structures, at 1.45 Å and 1.65 Å resolution, of CcmP from Synechococcus elongatus PCC7942 (SeCcmP). The central pore of CcmP is open or closed at its ends, depending on the conformation of two conserved residues, Glu69 and Arg70. The presence of glycerol resulted in a pore that is open at one end and closed at the opposite end. When glycerol was omitted, both ends of the barrel became closed. A binding pocket at the interior of the barrel featured residual density with distinct differences in size and shape depending on the conformation, open or closed, of the central pore of SeCcmP, suggestive of a metabolite-driven mechanism for the gating of the pore.

PubMed: 28369612
DOI: 10.1093/jxb/erx070

Experimental method

X-RAY DIFFRACTION (1.45 Å)