Regulation of the Intracellular Location of Methane Mono-oxygenase During Growth of Methylosinus trichosporium OB3b on Methanol

Abstract

The methane-oxidizing bacterium Methylosinus trichosporium OB3b retains the capacity to express two types of methane mono-oxygenase (MMO) during growth on methanol in continuous culture. Soluble MMO predominates during copper-limited growth whilst particulate (membrane-bound) MMO activity is expressed fully only in copper-sufficient cultures. Organisms containing soluble MMO oxidized ethylbenzene (an artificial substrate for soluble but not particulate MMO) but this capacity was progressively lost when additional copper was made available to the organism, and MMO activity was transferred to the particulate fraction of cell-free extracts. Although intracellular location of MMO is apparently regulated by copper availability during growth on both methane and methanol, whole-cell MMO activities are appreciably higher during growth on the former (natural) carbon source.