Current model for processes related to (a) copper homeostasis and methanobactin (Mbn) transport, regulation, and (b) biosynthesis in Methylosinus trichosporium OB3b. Abbreviations: ABC, ATP-binding cassette transporter; CuMbn, copper-chelated Mbn; ICM, intracytoplasmic membrane; IM, inner membrane; OM, outer membrane; pMMO, particulate methane monooxygenase; sMMO, soluble methane monooxygenase. Figure adapted with permission from References 25 and 215.