Cu(I) transport ATPases adapted to different temperatures

NOELIA MELIAN; LUIS M. BREDESTON; NOELIA I. BURGARDT; LURDES SABECKIS; F LUIS GONZÁLEZ FLECHA; ALVARO RECOULAT; M. AGUEDA PLACENTI

San Luis

Congreso; XLVIII Reunión Anual de la Sociedad Argentina de Biofísica; 2019

Sociedad Argentina de Biofísica

PIB-1-ATPases, also known as CopA,are integral membrane proteins that activelytransport Cu(I) ions through cell membrane coupled to ATP hydrolysis. Their function isessential for intracellular copper homeostasis, so they are widespread distributed innature. The structure of these proteins consists of four characteristic domains: the heavymetal associated domain (MBD), the catalytic domain (CD), the actuator domain (AD),and the transmembrane (TM) region constituted by eight α-helices. Also, they haveseveral conserved sequence motifs: the phosphorylation site (DKTG), the metal bindingsite (CXXC), the transmembrane metal binding site (CPC), and some invariable residuesof the transmembrane α-helices. In this work we present a comparative characterizationof CopAs from the psychrotolerant bacterium B. argentinensis (BaCopA), the mesophilicbacterium L. pneumophila (LpCopA) and the thermophilic archaea A. fulgidus (AfCopA).These proteins have more than 70% similarity and more than 40% identity betweenpairs, being the soluble metal binding domains the ones with the lowest similarity. Thehighest identity regions are found in the typical conserved motifs of P-ATPases and in thetransmembrane α-helices TM4, TM5 and TM6, where the PIB-1 subgroup conservedresidues and the transmembrane Cu(I) site are located. BaCopA (840 aa) has the largersize, followed by AfCopA (804 aa) and finally LpCopA (736 aa). However, the sizeexcluding the MBD presents a different order: BaCopA (650 aa) > LpCopA (644 aa) >AfCopA (621 aa). The differences in size are located in loops between α-helices MA-MB /TM1-TM2 and in loops of the catalytic domains. A comparison of the intraproteininteractions observed in BaCopA (model), LpCopA (3RFU), and AfCopA (3J08) shows thatthermophilic CopA have the higher amount of ionic interactions and the lower number ofaromatic-aromatic interactions. This suggest that thermal adaptations might modulatethe flexibility of these proteins by the length of those loops and the number ofintraprotein interactions. Indeed, recombinant purified CopAs show optimal activity atdifferent temperatures (BaCopA