| Popis: |
Cyanobacteria possess a host of proteases which unlike heterotrophs do not take part in protein nutrition. Instead, they maintain homeostasis of several vital functions, namely photosynthesis, nitrogen fixation, cellular assembly and disintegration, stress acclimation, and defense against predators. Herein, we review the Clp, FtsH, Deg/HtrA, Ctp, and SppA proteases, which under regular and photooxidative stress conditions maintain the integrity of photosynthetic and cytoplasmic membranes, periplasmic proteins, and photosystem particles, including the core complex protein, D1. The HetR protease by coordinating with the Alr3815 protease enables heterocyte differentiation and protection of nitrogenase from oxygen stress. The cell aggregation PteB proteases and caspases regulate the biomass density of cyanobacterial assemblages, and cyanophycinase mobilizes the reserve N, cyanophycin. Macrocyclization proteases mature up the ribosomally synthesized cyclic peptides of cyanobactin class with varied bioactivities. Numerous cyano-proteases listed in the UniProt database are homologues of eubacteria and higher plants with mostly unknown functions but with immense evolutionary significance in understanding the gene flow across bacteria and chloroplasts. Proteases are exclusive and therefore can be tailor-made to customize peptide drug synthesis and to formulate food additives and antimalarial, antivirulence, and antithrombotic agents. Notwithstanding these opportunities, taxonomic inadequacy and lack of proper nomenclature have adversely affected different biotechnological application processes. As a remedy, we propose that polyphasic approach of classification and reassessment of old taxonomic status may be necessary before patenting/commercialization of biotechnological processes/products. |
