Identification of a new gdh gene in Solanum lycopersicum

GISELA FERRARO; PABLO MORTERA; ESTELA M. VALLE

Carlos Paz

Congreso; XLIV Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB).; 2008

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB)

Glutamate dehydrogenase (GDH) catalyses a reversible reaction for the reductive amination of α-ketoglutarate to glutamate as well as the oxidative deamination of glutamate to α-ketoglutarate. Although GDH is ubiquitous in plant tissues, its physiological role is a subject of controversy. GDH is a hexamer comprised of two subunit polypeptides that differ slightly in mass and charge. The association of α and β subunits in the hexameric holoenzyme yields seven possible GDH isoenzymes. In several plant species these subunits are encoded by at least two distinct genes, however in tomato (Solanum lycopersicum) there is only one gene isolated, Slgdh B coding for the β subunit. Looking for other functional gdh gene in tomato, we searched in the transcript and genomic sequences available at Sol Genomic Network database (www.sgn.cornell.edu). We found a complete cDNA of 1604 bp, with a 56.9 % of identity to Slgdh B. This clone was highly similar to the genes encoding the α subunit of N. plumbaginifolia (87%), N. tabacum (88%), and A. thaliana (77%). We isolated the corresponding Slgdh A putative promoter and analyzed the predictive cis-acting elements. The expression of gdhB and the putative gdhA was studied in different tomato tissues by real time PCR and western blot analysis with antibodies that recognizes both subunits or only the α subunit. We found that the expression of both gdh genes varied differently in the tomato tissues analyzed. The isoenzyme profile suggest that these genes are independently regulated in tomato plants.