Acetoacetyl-CoA thiolase regulates the mevalonate pathway during abiotic stress adaptation

SOTO G; STRITZLER M; SETTEN L; LISI C; ALLEVA K; PAGANO E; ARDILA F; MOZZICAFREDDO M; CUCCIOLONI M; ANGELETTI M; AYUB ND

Potrero de los Funes, San Luis

Congreso; SAIB XLVII Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 2011

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular

ACETOACETYL-CoA THIOLASE REGULATES THEMEVALONATE PATHWAY DURING ABIOTIC STRESSADAPTATIONSoto, Stritzler, Setten, Lisi, Alleva, Pagano, Ardila, Mozzicafreddo,Cuccioloni, Angeletti, Ayub.Instituto de Genética Ewald A. Favret (CICVyA-INTA), Provincia deBuenos Aires, Argentina.Acetoacetyl-CoA thiolase, also called thiolase II, condenses twomolecules of acetyl-CoA to give acetoacetyl-CoA. This is the firstenzymatic step in the biosynthesis of isoprenoids via mevalonate(MVA).Thiolase II from alfalfa (MsAACT1) was identified andcloned. The enzymatic activity was experimentally demonstrated inplanta and in heterologous systems. The condensation reaction byMsAACT1 was proved to be inhibited by CoA suggesting a negativefeedback regulation of isoprenoid production. Real-time RT-PCRanalysis indicated that MsAACT1 expression is highly increased inroots and leaves under cold and salinity stress. Treatment withmevastatin, a specific inhibitor of the MVA pathway, resulted in adecrease in squalene production, antioxidant activity, and thesurvival of stressed plants. The addition of vitamin C suppressed thesensitive phenotype of plants challenged with mevastatin,suggesting a critical function of the MVA pathway in abiotic stressinducibleantioxidant defence. MsAACT1 over-expressingtransgenic plants showed salinity tolerance comparable with emptyvector transformed plants and enhanced production of squalene.Thus, acetoacetyl-CoA thiolase is a regulatory enzyme in isoprenoidbiosynthesis involved in abiotic stress adaptation.