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Title: The Structure of a Cyanobacterial Bicarbonate Transport Protein, CmpA

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 CO₂concentrating machinery of which the ABC transport system CmpABCD from Synechocystis PCC 6803 is one component. Here we describe 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 to 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 is highly cooperative and suggests that CmpA co-transports bicarbonate and calcium.

Authors:
; ; ;
Publication Date:
Research Org.:
Pacific Northwest National Laboratory (PNNL), Richland, WA (US), Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org.:
USDOE
OSTI Identifier:
898618
Report Number(s):
PNNL-SA-52280
16720; 14398; TRN: US200706%%232
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Biological Chemistry, 282(4):2606-2614
Country of Publication:
United States
Language:
English
Subject:
09 BIOMASS FUELS; ACID CARBONATES; AUTOTROPHS; BIOMASS; CALCIUM; CARBON; CARBONIC ACID; CYANOBACTERIA; FOOD CHAINS; MACHINERY; NITRATES; NITROGEN; SPECTROSCOPY; TRANSPORT; Cyanobacteria; CmpA; Environmental Molecular Sciences Laboratory

Citation Formats

Koropatkin, Nicole M., Koppenaal, David W., Pakrasi, Himadri B., and Smith, Thomas J.. The Structure of a Cyanobacterial Bicarbonate Transport Protein, CmpA. United States: N. p., 2007. Web. doi:10.1074/jbc.M610222200.
Koropatkin, Nicole M., Koppenaal, David W., Pakrasi, Himadri B., & Smith, Thomas J.. The Structure of a Cyanobacterial Bicarbonate Transport Protein, CmpA. United States. doi:10.1074/jbc.M610222200.
Koropatkin, Nicole M., Koppenaal, David W., Pakrasi, Himadri B., and Smith, Thomas J.. Fri . "The Structure of a Cyanobacterial Bicarbonate Transport Protein, CmpA". United States. doi:10.1074/jbc.M610222200.
@article{osti_898618,
title = {The Structure of a Cyanobacterial Bicarbonate Transport Protein, CmpA},
author = {Koropatkin, Nicole M. and Koppenaal, David W. and Pakrasi, Himadri B. and Smith, Thomas J.},
abstractNote = {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 CO₂concentrating machinery of which the ABC transport system CmpABCD from Synechocystis PCC 6803 is one component. Here we describe 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 to 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 is highly cooperative and suggests that CmpA co-transports bicarbonate and calcium.},
doi = {10.1074/jbc.M610222200},
journal = {Journal of Biological Chemistry, 282(4):2606-2614},
number = ,
volume = ,
place = {United States},
year = {Fri Jan 26 00:00:00 EST 2007},
month = {Fri Jan 26 00:00:00 EST 2007}
}