(361a) Structural Studies of a Cyanobacterial Bicarbonate Uptake Regulator

Cyanobacteria play an essential role in global photosynthetic carbon fixation. The principal source of inorganic carbon for cyanobacteria is bicarbonate, which must be transported across the cell membrane by a group of unique integral membrane transporters before its ultimate fixation in the carboxysome. Current understandings of how these individual transporters function and how they are regulated, however, is severely limited due in large part to the scarce availability of structural and functional information. Here we report on the characterization and structural studies of SbtB, which interacts with and regulates of one of the key bicarbonate transporters in cyanobacteria. We have expressed, purified, and crystallized StbB, and determined its high-resolution structure by X-ray crystallography. This high-resolution structure has provided valuable insight into how SbtB may interact with and regulate bicarbonate transporter activity.