Biological Assembly 1  

 3D View: Structure | 1D-3D View | Electron Density | Validation Report

Global Symmetry: Asymmetric - C1 
Global Stoichiometry: Monomer - A1 

Biological assembly 1 assigned by authors.

Macromolecule Content

• Total Structure Weight: 47.09 kDa 
• Atom Count: 3530 
• Modelled Residue Count: 398 
• Deposited Residue Count: 429 
• Unique protein chains: 1

2I49

Crystal structure of apo form of Bicarbonate Transport Protein CmpA from Synechocystis sp. PCC 6803

• PDB DOI: 10.2210/pdb2I49/pdb

• Classification: TRANSPORT PROTEIN
• Organism(s): Synechocystis sp. PCC 6803
• Expression System: Escherichia coli
• Mutation(s): No 


• Deposited: 2006-08-21 Released: 2006-12-19 
• Deposition Author(s): Koropatkin, N.M., Smith, T.J., Pakrasi, H.B.

---

Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 1.35 Å
• R-Value Free: 0.193 
• R-Value Work: 0.178 
• R-Value Observed: 0.178 

Literature

The Structure of a Cyanobacterial Bicarbonate Transport Protein, CmpA.

Koropatkin, N.M., Koppenaal, D.W., Pakrasi, H.B., Smith, T.J.

(2007) J Biol Chem 282: 2606-2614

• PubMed: 17121816 
• DOI: 10.1074/jbc.M610222200
• Primary Citation of Related Structures:  
  2I48, 2I49, 2I4B, 2I4C


• PubMed Abstract: 
  

Cyanobacteria, blue-green algae, are the most abundant autotrophs in aquatic environments and form the base of the food chain by fixing carbon and nitrogen into cellular biomass. To compensate for the low selectivity of Rubisco for CO2 over O2, cyanobacteria have developed highly efficient CO2-concentrating machinery of which the ABC transport system CmpABCD from Synechocystis PCC 6803 is one component. Here, we have described the structure of the bicarbonate-binding protein CmpA in the absence and presence of bicarbonate and carbonic acid. CmpA is highly homologous to the nitrate transport protein NrtA. CmpA binds carbonic acid at the entrance to the ligand-binding pocket, whereas bicarbonate binds in nearly an identical location compared with nitrate binding to NrtA. Unexpectedly, bicarbonate binding is accompanied by a metal ion, identified as Ca2+ via inductively coupled plasma optical emission spectrometry. The binding of bicarbonate and metal appears to be highly cooperative and suggests that CmpA may co-transport bicarbonate and calcium or that calcium acts a cofactor in bicarbonate transport.

---

Organizational Affiliation: 

Donald Danforth Plant Science Center, St. Louis, Missouri 63132, USA.

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
Bicarbonate transporter	A	429	Synechocystis sp. PCC 6803	Mutation(s): 0  Gene Names: cmpA
UniProt
Find proteins for Q55460 (Synechocystis sp. (strain PCC 6803 / Kazusa)) Explore Q55460  Go to UniProtKB:  Q55460

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• Resolution: 1.35 Å
• R-Value Free: 0.193 
• R-Value Work: 0.178 
• R-Value Observed: 0.178 
• Space Group: P 1

Unit Cell:

Length ( Å )	Angle ( ˚ )
a = 44.66	α = 87.57
b = 49.68	β = 81.2
c = 57.57	γ = 75.2

Software Package:

Software Name	Purpose
CNS	refinement
PDB_EXTRACT	data extraction
PROTEUM PLUS	data collection
SAINT	data reduction
PROTEUM PLUS	data scaling
AMoRE	phasing

Structure Validation

Entry History 

Deposition Data

• Deposited Date: 2006-08-21 
• Released Date: 2006-12-19 
Deposition Author(s): Koropatkin, N.M., Smith, T.J., Pakrasi, H.B.

Revision History  

• Version 1.0: 2006-12-19
  Type: Initial release
  
• Version 1.1: 2008-05-01
  Changes: Version format compliance
• Version 1.2: 2011-07-13
  Changes: Source and taxonomy, Version format compliance