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

Abstract

Abstract-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.