ROLE OF ALKALINE/NETURAL INVERTASES IN Anabaena STRAINS IN RESPONSE TO A SALT STRESS

NISHI CN, VARGAS WA, PONTIS HG, SALERNO GL

Mar del PLata

Congreso; 44th Annual Meeting of the Argentine Society for Biochemistry and Molecular Biology; 2008

In Anabaena (Nostoc) sp. PCC 7120, we had identified and biochemically characterized two alkaline/neutral invertase genes (invA and invB) coding for proteins of about 53-55 kDa. The aim of this work was to investigate if those isozymes play different roles in the Anabaena filaments. Expression analysis, localization of InvA and InvB in N2-fixing filament cells, evidenced with transcriptional fusions of an optimized version of the green fluorescent protein (GFP) gene (gfp-mut2) to putative promoters of invA and invB, and phenotipic characterization of Anabaena mutant strains where inv genes were disrupted, supported the importance of alkaline/neutral invertases, and particularly invB, in diazotrophic growth. On the other hand, a key function of alkaline/neutral invertases in salt tolerance was demonstrated by expression analysis at the transcriptional, traslational and activity level. The impair in alkaline/neutral invertase activity affect salt tolerance. Taken together our results, we conclude that a high sucrose turnover seems to be important to cope salt stress.