Mutagenesis of a Copper P-Type ATPase Encoding Genein Methylococcus capsulatus (Bath) Results inCopper-Resistance

Copper is an essential micronutrient for all living cells, however, it is extremely toxic at high concentrations and thus copper homeostasis is required to be tightly regulated. copA encodes for a copper-translocating P-type ATPase (CopA) and plays a vital role in copper homeostasis and is involved in copper transport across membranes of many organisms. Little is known about copper homeostasis in Methylococcus capsulatus although copper has a significant physiological role in this methanotroph. In this study we investigated the disruption of a CopA1 homologue (MCA2072; copA1) in M. capsulatus (Bath) by insertional inactivation mutagenesis. The resulting mutant, M. capsulatus ΔcopA1, was copper resistant to elevated copper concentrations (100 μM) than the wild-type strain (80 μM). Furthermore, the intracellular copper measurements revealed that ΔcopA1 accumulated half the amount of copper when compared with the wild-type. No observed phenotypic difference between the mutant strain and wild-type related to growth at different silver concentrations. These observations suggest that M. capsulatus CopA1 has a key role in copper homeostasis.