Gene Manipulation and Biosynthesis of Phycobiliproteins

Abstract

The phycobiliproteins (PBPs) are a family of accessory light-harvesting protein complexes found in cyanobacteria, red algae, and cryptomonads. They are associated with noncyclic linear/open-chain tetrapyrrole prosthetic groups that consist of four pyrrole rings (A, B, C, and D) integrated in α, β, and γ biliproteins. Commonly, PBPs are associated with αβ heterodimers in which each subunit carries bilin(s) thioether-linked to particular cysteinyl residues.On the basis of chromophore structure, there are four kinds of phycobilins found in cyanobacteria: phycoerythrobilin (PEB), phycocyanobilin (PCB), phycourobilin (PUB), and phycoviolobilin (PVB). Moreover, nonpigmented linker polypeptides are embedded in the structure which are responsible for stabilization and modulation of energy absorption within PBPs and help in effective energy transfers toward the photosystem. Much progress has been made about understanding the biosynthesis mechanism of PBPs. However, there is still limitation to utilize the biosynthetic pathway of PBPs for more production to fulfill demand of the global economy. This chapter provides the details on studies about the mechanism of biosynthesis of PBPs and probable involvement of genes and enzymes which act as precursors.