IQUIFIB   02644
INSTITUTO DE QUIMICA Y FISICOQUIMICA BIOLOGICAS "PROF. ALEJANDRO C. PALADINI"
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Conformational ensamble in the isolated soluble ATP binding domain of CopA, a thermophilic membrane protein, is modulated by a cracking-like mechanism
Autor/es:
SANTIAGO MARTINEZ GACHE; PETER WOLYNES; RODOLFO M. GONZALEZ LEBRERO; ERNESTO A. ROMAN
Lugar:
Rio de Janeiro
Reunión:
Congreso; Latin American Protein Society; 2016
Institución organizadora:
Latin American Protein Society
Resumen:
p { margin-bottom: 0.25cm; direction: ltr; color: rgb(0, 0, 0); line-height: 120%; text-align: left; }p.western { font-family: "Arial",sans-serif; font-size: 11pt; }p.cjk { font-family: "Arial",sans-serif; font-size: 11pt; }p.ctl { font-family: "Arial",sans-serif; font-size: 10pt; }P-typeATPases are integral membrane proteins whichcouples the cations transport to ATP hydrolysis performed in theglobular ATP binding domain (ATPBD) which is composed by twosubdomains. Crystallographic information shows that in the absence ofATP resembles an open conformation while when ATP is bound itresembles a closed conformation. heisolated catalytic domain of Archaeoglobus fulgidus Cu(I) transporterATPase displays ATPase activity and it shows a closed conformation inthe presence of ATP (PDB-ID 3A1C) and a partially closed in itsabsence (PDB ID 2B8E).Hereweexplored the existence of this open conformation inquiringwhyhomologs visit this conformation while this protein not. We proposethat thermophilicity and flexibility are related in protein motionsleading to a kinetic/thermodynamic trap thatinhibits the open-close transition belowits functional temperature.ATPBDtryptophan fluorescence revealeda single transition when heating from 10 to 80 C, while no transitionwas observed in circular dichroism . This is consistent with arelative movement between the ATPBD subdomainswhichis compatible with an open/close transition.Simulationsusingthe AssociativeMemory, Water-Mediated, Structure and Energy Modelshowedthat at a single temperature the ensemble of conformations in theabsence of ATP exists principally in the partially closed state,however, as temperature increases the open conformation is populatedsuggesting a temperature trigger. Using structure-based models weperformed simulations turning on/off contacts formed in ATPBD closedform. The observed open-close transitions occur with an increase inthe potential energy in the region between the two subdomainsresembling a cracking mechanism. Inconclusion, the temperature dependence of the conformational ensembleof ATPBD suggest that cracking-like mechanisms seems to modulate andlimit the set of structures visited. Local frustration seems to playan important role. How this effect is related to protein functionremains to be explored.