Carbon-Concentrating Mechanism of Cyanobacteria

Abstract

The Gram-negative photosynthetic prokaryotes, cyanobacteria, are thought to be appeared on earth approximately 2,600–3,500 million years ago. Due to their carbon-concentrating mechanism (CCM) system, they are extremely productive and flourish under a wide range of niches. Molecular and biochemical evidence indicates that cyanobacterial CCMs feature multiple active Ci transporters, including three transporters for \({\text{HCO}}_{3}^{ - }\) (at plasma membrane) and two uptake systems for CO2 (at thylakoid membrane). A pool of bicarbonate ion is accumulated within the cell and this is used by the RuBisCO-containing carboxysome to generate CO2 within this localized micro-environment. Carboxysomal carbonic anhydrase is also play a crucial role to this CO2 generation process. This chapter examines the mechanism of the operation of carbon concentrating mechanisms (CCMs) in cyanobacteria in the view of latest findings.