Cyanobacterial Mn-catalase ‘KatB’: Molecular link between salinity and oxidative stress resistance

• Main Authors: Dhiman Chakravarty, Manisha Banerjee, Namrata Waghmare, Anand Ballal
• Format: Article
• Language: English
• Published: Taylor & Francis Group 2016-09-01
• Series: Communicative & Integrative Biology
• Subjects: biofertilizers; cross-protection; cyanobacteria; manganese catalase; oxidative stress; salinity stress
• Online Access: http://dx.doi.org/10.1080/19420889.2016.1216738

Catalases are ubiquitous enzymes that detoxify H2O2 in virtually all organisms exposed to oxygen. The filamentous, nitrogen-fixing cyanobacterium, Anabaena PCC 7120, shows the presence of 2 genes (katA and katB) that encode Mn-catalases. We have recently shown that pre-treatment of Anabaena with NaCl causes substantial induction of the KatB protein, which consequently leads to increased oxidative stress resistance in that cyanobacterium. Interestingly, when compared to the wild-type, the katB mutant shows decreased growth and impaired photosynthetic activity in the presence of NaCl. Furthermore, the NaCl-treated katB mutant is extremely sensitive to H2O2. In this study, the ultrastructural changes occurring in the katB mutant and the wild-type Anabaena cells are analyzed to understand the cellular basis of the above-mentioned protective phenomena. Other data show that a wide variety of osmolytes induce katB expression in Anabaena, indicating that katB is a genuine osmo-inducible gene. These results have important biotechnological implications for the development of novel cyanobacterial biofertilzers and transgenic plants with improved resistance to salinity.