Cyanobacterial Mn-catalase 'KatB': Molecular link between salinity and oxidative stress resistance.
Catalases are ubiquitous enzymes that detoxify H2O2in virtually all organisms exposed to oxygen. The filamentous, nitrogen-fixing cyanobacterium,AnabaenaPCC 7120, shows the presence of 2 genes (katAandkatB) that encode Mn-catalases. We have recently shown that pre-treatment ofAnabaenawith 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, thekatBmutant shows decreased growth and impaired photosynthetic activity in the presence of NaCl. Furthermore, the NaCl-treatedkatBmutant is extremely sensitive to H2O2. In this study, the ultrastructural changes occurring in thekatBmutant and the wild-typeAnabaenacells are analyzed to understand the cellular basis of the above-mentioned protective phenomena. Other data show that a wide variety of osmolytes inducekatBexpression inAnabaena, indicating thatkatBis 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.
Molecular Biology Division, Bhabha Atomic Research Center, Trombay, Mumbai, India; Homi Bhabha National Institute, Anushakti Nagar, Mumbai, India.
Dhiman
D
Chakravarty
Molecular Biology Division, Bhabha Atomic Research Center , Trombay, Mumbai, India.
Manisha
M
Banerjee
Molecular Biology Division, Bhabha Atomic Research Center , Trombay, Mumbai, India.
Namrata
N
Waghmare
Molecular Biology Division, Bhabha Atomic Research Center, Trombay, Mumbai, India; Homi Bhabha National Institute, Anushakti Nagar, Mumbai, India.
Anand
A
Ballal
biofertilizers; cross-protection; cyanobacteria; manganese catalase; oxidative stress; salinity stress