Hydrocarbon monooxygenase in Mycobacterium: recombinant expression of a member of the ammonia monooxygenase superfamily

Nicholas V. Coleman, Nga B. Le, Mai A. Ly, Hitoha E. Ogawa, Victoria McCarl, Neil L. LWilson, Andrew J. Holmes*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

44 Citations (Scopus)

Abstract

The copper membrane monooxygenases (CuMMOs) are an important group of enzymes in environmental science and biotechnology. Areas of relevance include the development of green chemistry for sustainable exploitation of methane (CH(4)) reserves, remediation of chlorinated hydrocarbon contamination and monitoring human impact in the biogeochemical cycles of CH(4) and nitrogen. Challenges for all these applications are that many aspects of the ecology, physiology and structure-function relationships in the CuMMOs are inadequately understood. Here, we describe genetic and physiological characterization of a novel member of the CuMMO family that has an unusual physiological substrate range (C2-C4 alkanes) and a distinctive bacterial host (Mycobacterium). The Mycobacterial CuMMO genes (designated hmoCAB) were amenable to heterologous expression in M. smegmatis-this is the first example of recombinant expression of a complete and highly active CuMMO enzyme. The apparent specific activity of recombinant cells containing hmoCAB ranged from 2 to 3 nmol min-1 per mg protein on ethane, propane and butane as substrates, and the recombinants could also attack ethene, cis-dichloroethene and 1,2-dichloroethane. No detectable activity of recombinants or wild-type strains was seen with methane. The specific inhibitor allylthiourea strongly inhibited growth of wild-type cells on C2-C4 alkanes, and omission of copper from the medium had a similar effect, confirming the physiological role of the CuMMO for growth on alkanes. The hydrocarbon monooxygenase provides a new model for studying this important enzyme family, and the recombinant expression system will enable biochemical and molecular biological experiments (for example, site-directed mutagenesis) that were previously not possible.

Original languageEnglish
Pages (from-to)171-182
Number of pages12
JournalThe ISME Journal: multidisciplinary journal of microbial ecology
Volume6
Issue number1
Early online date28 Jul 2011
DOIs
Publication statusPublished - Jan 2012
Externally publishedYes

Keywords

  • methane monooxygenase
  • ammonia monooxygenase
  • hydrocarbon monooxygenase
  • Mycobacterium
  • alkane
  • biogeochemistry

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