The role of Alkaline- Neutral Invertases during salt stress in the filamentous nitrogen-fixing cyanobacterium Anabaena sp. PCC 7120

NISHI, C.N.; VARGAS, W.A.; SALERNO, G.L.

Porto

Simposio; 14th International Symposium on Phototrophic Prokaryotes; 2012

International Society on Phototrophic Prokaryotes

All organisms have to cope to the constantly changing environment in order to survive, and cyanobacteria are by no means the exception to that. In particular, cyanobacteria can grow under a wide range of environmental conditions, including salinity. Stenohaline cyanobacteria (with low salt tolerance) accumulate various low molecular osmolytes such as Sucrose (Suc), trehalose, sucroglucans and others compounds. Suc is one of the most abundant disaccharide in Nature and was reported to be present in oxygenic photosynthetic organisms. In particular, in the filamentous N-fixing Anabaena sp. PCC 7120, Suc metabolism has been characterized biochemically, functionally and physiologically in the last 20 years. In this model organism, Suc can be hydrolyzed by Alkaline-Neutral Invertases (A/N-Inv). Two different isoforms of A/N-Invs were reported (Inv-A and Inv-B) [1]. In this study, we have demonstrated that both A/N-Invs are involved in the accumulation of Suc and Sucroglucans, as well as glycogen after the addition of 80 mM NaCl. However, they are not essential for the growth of Anabaena sp. PCC 7120 in conditions of salt stress as shown in different experiments where the null mutants did not show any differences in their growth. Taken together, our results let us conclude that Suc in not just a mere osmolyte, but it is central for the carbon allocation in Anabaena sp. PCC 7120. Furthermore, A/N-Invs would be involved in the accumulation of Suc and Sucroglucans, and therefore, the tolerance to salt stress.