A putative HCO3 transporter in the cyanobacterium Synechococcus sp. strain PCC 79421

Abstract
Cyanobacteria possess an inducible mechanism which enables them to concentrate inorganic carbon (Ci) within the cells. An inactivation library was used to raise the high-CO2-requiring mutant of Synechococcus PCC 7942, IL-2, impaired in HCO 3 transport. Analysis of the relevant genomic DNA detected several modifications, probably due to the single crossover recombination, leading to inactivation of ORF467 (designated ictB) in IL-2. IctB contains 10 trans-membrane regions and is homologous to several transport-related proteins from various organisms. Kinetic analyses of HCO 3 uptake in the wild type and IL-2 suggested the presence of two or three HCO 3 carriers exhibiting different affinities to HCO 3.