# Copper resistance in the cold: Genome analysis and characterisation of a PIB‐1 ATPase in Bizionia argentinensis

## TL;DR

This study identifies and characterizes a copper-transporting protein in a cold-adapted Antarctic bacterium, revealing how it functions at low temperatures.

## Contribution

The first functional expression and purification of a psychrotolerant P1B-ATPase involved in copper homeostasis.

## Key findings

- BaCopA1, a P1B-type ATPase from Bizionia argentinensis, was expressed in yeast and catalyzed ATP hydrolysis at low temperatures.
- Structural models of BaCopA1 show conservation of key residues and similarity to mesophilic and thermophilic homologs, suggesting a shared copper transport mechanism.

## Abstract

Copper homeostasis is a fundamental process in organisms, characterised by unique pathways that have evolved to meet specific needs while preserving core resistance mechanisms. While these systems are well‐documented in model bacteria, information on copper resistance in species adapted to cold environments is scarce. This study investigates the potential genes related to copper homeostasis in the genome of Bizionia argentinensis (JUB59‐T), a psychrotolerant bacterium isolated from Antarctic seawater. We identified several genes encoding proteins analogous to those crucial for copper homeostasis, including three sequences of copper‐transport P1B‐type ATPases. One of these, referred to as BaCopA1, was chosen for cloning and expression in Saccharomyces cerevisiae. BaCopA1 was successfully integrated into yeast membranes and subsequently extracted with detergent. The purified BaCopA1 demonstrated the ability to catalyse ATP hydrolysis at low temperatures. Structural models of various BaCopA1 conformations were generated and compared with mesophilic and thermophilic homologous structures. The significant conservation of critical residues and structural similarity among these proteins suggest a shared reaction mechanism for copper transport. This study is the first to report a psychrotolerant P1B‐ATPase that has been expressed and purified in a functional form.

This study explores copper homeostasis in Bizionia argentinensis, a psychrotolerant bacterium from Antarctic seawater. The genome reveals genes similar to known copper homeostasis proteins, including a P1B‐type ATPase, BaCopA1. Expressed in yeast, BaCopA1 catalyses ATP hydrolysis at low temperatures. Its structural similarity to other proteins suggests a shared copper transport mechanism.