
TY  - JOUR
A1  - Omata, Tatsuo 
A1  - Takahashi, Yukari 
A1  - Yamaguchi, Osamu 
A1  - Nishimura, Takashi 
T1  - Structure, function and regulation of the cyanobacterial high-affinity bicarbonate transporter, BCT1
JF  - Functional Plant Biology
JO  - Functional Plant Biol.
Y1  - 2002
VL  - 29
IS  - 3
SP  - 151
EP  - 159
KW  - ABC transporter, bicarbonate transporter, CO2 concentrating mechanism, cyanobacteria.
UR  - https://doi.org/10.1071/PP01215 
N2  - The cmpABCD operon of the cyanobacterium Synechococcus sp. strain PCC7942, which is transcribed specifically under CO2-limited growth conditions, encodes an ATP-binding cassette (ABC) transporter involved in HCO3&#8211;uptake (designated BCT1). The product of the cmpA gene is a 42-kDa protein anchored to the plasma membrane, which binds HCO3&#8211; with high affinity (Kd= 5 &#181;M) and acts as the substrate-binding protein of the transporter. The apparent Km(HCO3&#8211;) of BCT1 is 15 &#181;M. BCT1 has the highest affinity for HCO3&#8211; among the HCO3&#8211; transporters of the Synechococcus strain and is essential for competitive utilization of HCO3&#8211; under CO2-limited conditions. BCT1 is closely related to the cyanobacterial nitrate/nitrite transporter (NRT) encoded by the nrtABCD genes. The BCT1 and NRT transporters, together with the putative cyanate transporter of cyanobacteria, comprise a monoanion transporter subfamily in the family of ABC importers. BCT1 and NRT are present in most fresh-water strains of cyanobacteria but seem to be absent in marine cyanobacterial strains. The low CO2-responsive induction of thecmp operon requires a LysR family protein CmpR, which is similar to CbbR (RbcR), the activator of the CO2 fixation operons of chemoautotrophic and purple photosynthetic bacteria. 
ER  -

