PDBsum entry 5lsr

Transport protein

PDB id: 5lsr

Contents

Protein chains

205 a.a.

Ligands

SCN ×2

Waters ×357

PDB id:

5lsr

Name:

Transport protein

Title:

Carboxysome shell protein ccmp from synechococcus elongatus pcc 7942

Structure:

Ccmp. Chain: a, b, c. Engineered: yes

Source:

Synechococcus elongatus pcc 7942. Organism_taxid: 1140. Gene: synpcc7942_0520. Expressed in: escherichia coli bl21. Expression_system_taxid: 511693. Expression_system_variant: ai

Resolution:

1.65Å R-factor: 0.182 R-free: 0.191

Authors:

A.M.Larsson,D.Hasse,K.Valegard,I.Andersson

Key ref:

A.M.Larsson et al. (2017). Crystal structures of β-carboxysome shell protein CcmP: ligand binding correlates with the closed or open central pore. J Exp Bot, 68, 3857-3867. PubMed id: 28369612 DOI: 10.1093/jxb/erx070

Date:

05-Sep-16 Release date: 12-Apr-17

Protein chains

Q31QW7  (CCMP_SYNE7) -  Carboxysome shell protein CcmP from Synechococcus elongatus (strain ATCC 33912 / PCC 7942 / FACHB-805)

Seq: 213 a.a.

Struc: 205 a.a.

Enzyme reactions

• Enzyme class: E.C.?

DOI no: 10.1093/jxb/erx070

J Exp Bot 68:3857-3867 (2017)

PubMed id: 28369612

Crystal structures of β-carboxysome shell protein CcmP: ligand binding correlates with the closed or open central pore.

A.M.Larsson, D.Hasse, K.Valegård, I.Andersson.

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.