“Molecular characterization of StPPI, a Solanum tuberosum proton pump interactor”

MUÑIZ GARCÍA MN; PAIS SM; TÉLLEZ-IÑÓN MT; CAPIATI D

Tucumán, Argentina

Congreso; XLV Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2009

Sociedad Argentina de Investigacion en Biologia

Plasma membrane proton pumps (PM H+-ATPases) are P-type ATPases that generate an electrochemical proton gradient across the plasma membrane, which drives the transport of solutes and regulate cytoplasmic and apoplastic pH. PM H+-ATPases participate in various physiological processes such as phloem loading, stomata opening, mineral nutrition, salt and osmotolerance. The major regulators of the PM H+-ATPases are 14-3-3 proteins, which interact with the ATPase C-terminus auto-inhibitory domain, thereby relieving its effect and stimulating proton pumping. A novel interactor of the PM H+-ATPase, PPI1 (proton pump interactor, isoform 1), was identified in Arabidopsis thaliana. This protein binds to the PM H+-ATPase and stimulates its activity in vitro. In this work, we have identified and characterized a Solanum tuberosum homologue of the Arabidopsis PPI1, named StPPI. The gene structure was studied, establishing the position and size of introns and exons by a PCR approach. Southern blot analysis revealed that StPPI is a single-copy gene. Expression profiles of StPPI under different environmental conditions were determined by Northern blot, providing evidence of the participation of StPPI in abiotic stress responses. The full length StPPI was expressed as a fusion with His tag (His-StPPI) in E. Coli and the recombinant protein have shown to increase PM H+-ATPase activity in vitro.