INVESTIGADORES
MANGIALAVORI Irene Cecilia
congresos y reuniones científicas
Título:
Lipid structure affects the activity of integral membrane proteins: PMCA as a model
Autor/es:
MARIA FLORENCIA PIGNATARO; MARTÍN DODES TRAIAN; LUIS GONZALEZ-FLECHA; IRENE MANGIALAVORI; JUAN PABLO ROSSI
Reunión:
Congreso; XLII. Reunión Anual de la Sociedad Argentina de Biofísica; 2013
Resumen:
Integral membrane proteins have central roles in a
vast number of vital cellular processes. The enzymic activity of these proteins
is affected by the structures of the lipid molecules that surround them in the
membrane. The effects of lipid structure on a membrane protein are likely to be
complex and unique for each membrane protein. As a model, we chose the plasma
membrane calcium pump (PMCA), an integral membrane protein that regulates the
intracellular calcium level. In the present work, purified PMCA was
reconstituted into different phospholipid-detergent mixed micelles to relate Ca2+-ATPase
activity with the lipid environment. We found that: ATPase activity depends on
the carbon chain length and on the molar fraction (XPL) of the
phospholipid in the mixed micelle. From XPL= 0.4, there is a drop in
ATPase activity for the majority of the assayed phospholipids, except for 1,2-Dilauroyl-sn-glycero-3-phosphocholine
(DLPC). To understand this
behavior, we studied the biophysical properties of those reconstitution systems
and found that there was a micelle-vesicle transition starting from XPL=0.3
(followed by Fluorescence Correlation Spectroscopy and Static Light Scattering)
for most of the phospholipids. DLPC was also the exception and the transition
was found at higher XPL. These results provide insights to develop a
model that links the biophysical properties of the system with the enzymatic
activity.
With grants of
CONICET, FONCyT and UBA.