Effect of ions and lipids on ATPase activity of the Spf1 P5- ATPase from Saccharomyces cerevisiae.

HUGO P. ADAMO; GUIDO D. PETROVICH; GERARDO R. CORRADI

La Plata

Congreso; XLVII Reunión Anual de la Sociedad Argentina de Biofísica; 2018

P-type ATPases (P1 to P5) are integral membrane proteins that transport differentligands against its concentration gradient, through ATP hydrolysis. P5-ATPases arethe least studied members of the whole family of P-ATPases and its transportedsubstrate remains unknown. Several human P5-ATPases are implicated inneurological disorders, as the Kufor-Rakeb syndrome, a parkinsonism withdementia, hereditary spastic paraplegia, neuronal ceroid lipofuscinosis, autism andintellectual disability. With the aim of advancing the knowledge of P5-ATPases wehave investigated the effect of lipids and ions on the ATPase activity of therecombinant Spf1 P5-ATPase of Saccharomyces cerevisiae. The highest levels ofATPase activity were achieved when asolectin from soybean was used tosupplement the micelar preparation of the protein indicating that asolectin makesthe best micelar environment for Spf1 ATP hydrolysis . While monovalent ionsdidn?t affect ATPase activity Spf1, it was inhibited by mercury, aluminum,lanthanum and cadmium. Like other P-ATPases, Spf1 required magnesium tohydrolyze ATP. The dependence of Spf1 ATPase activity with Mg2+ was best fittedby a double hyperbola, a fact that could indicate the existence of two binding sitesfor magnesium. On the other hand, high concentration of other divalent cationsreduced the ATPase activity. Interestingly, the Spf1 ATPase had a biphasicdependency with zinc. At low concentrations zinc increased the ATPase while itproduced inhibition at higher concentrations. High inhibitory concentrations zincin the presence of ATP changed the sensibility of Spf1 to chymotrypsin suggestingthe stabilization of an inhibited conformation.