INVESTIGADORES
SALERNO Graciela Lidia
artículos
Título:
Differential roles of alkaline/neutral invertases in Nostoc sp. PCC 7120: Inv-B isoform is essential for diazotrophic growth
Autor/es:
W.A. VARGAS; C.N. NISHI; L.E. GIARROCCO; G.L. SALERNO
Revista:
PLANTA
Editorial:
SPRINGER
Referencias:
Año: 2011 vol. 233 p. 153 - 162
ISSN:
0032-0935
Resumen:
The presence of
two alkaline/neutral invertases (Inv-A and Inv-B) in the filaments of Nostoc (also named Anabaena) sp. strain PCC 7120 and the involvement of sucrose
metabolism in nitrogen fixation, led us to investigate the physiological
function of those isoforms in cells growing under different nitrogen sources.
The highest expression level of each encoding gene was obtained in the presence
of ammonium. These results were paralleled by polypeptide and enzyme activity level.
In cells of N2-fixing filaments, localization of gene expression and
subcellular enzyme activity assays demonstrated that invA gene (alr1152) expresses only in vegetative cells, whereas for invB (alr0819), expression is detected in both
vegetative cells and heterocysts. In contrast to invA, when invB was knocked
out, the filaments were unable to grow on diazotrophic conditions and the
accumulation of sucrose and glycogen was altered. Our results demonstrate an
essential role for Inv-B for diazotrophic growth, and that Inv-B plays a key
role in the coordination of sucrose and glycogen metabolism. We can also
suggest that invB is likely to integrate the repertoire of genes regulated by a
cyanobacterial transcription factor (NtcA) that plays a central role in global
nitrogen control.