Distinct functions of serial metal-binding domains in the Escherichia coli P^sub 1B^-ATPase CopA

• Published in: Molecular microbiology Vol. 97; no. 3; p. 423
• Main Authors: Drees, Steffen L, Beyer, Dominik F, Lenders-Lomscher, Christina, Lübben, Mathias
• Format: Journal Article
• Language: English
• Published: Oxford Blackwell Publishing Ltd 01-08-2015
• Subjects: Adenosine triphosphatase; Binding sites; Copper; Cytoplasm; E coli; Proteins
• ISSN: 0950-382X; 1365-2958

P1B-ATPases are among the most common resistance factors to metal-induced stress. Belonging to the superfamily of P-type ATPases, they are capable of exporting transition metal ions at the expense of adenosine triphosphate (ATP) hydrolysis. P1B-ATPases share a conserved structure of three cytoplasmic domains linked by a transmembrane domain. In addition, they possess a unique class of domains located at the N-terminus. In bacteria, these domains are primarily associated with metal binding and either occur individually or as serial copies of each other. Within this study, the roles of the two adjacent metal-binding domains (MBDs) of CopA, the copper export ATPase of Escherichia coli were investigated. From biochemical and physiological data, we deciphered the protein-internal pathway of copper and demonstrate the distal N-terminal MBD to possess a function analogous to the metallochaperones of related prokaryotic copper resistance systems, that is its involvement in the copper transfer to the membrane-integral ion-binding sites of CopA. In contrast, the proximal domain MBD2 has a regulatory role by suppressing the catalytic activity of CopA in absence of copper. Furthermore, we propose a general functional divergence of tandem MBDs in P1B-ATPases, which is governed by the length of the inter-domain linker.