title: Bacteriohemerythrin bolsters the activity of the particulate methane monooxygenase (pMMO) in Methylococcus capsulatus (Bath).
abstract: Recently, a native bacteriohemerythrin (McHr) has been identified in Methylococcus capsulatus (Bath). Both the particulate methane monooxygenase (pMMO) and McHr are over-expressed in cells of this bacterium when this strain of methanotroph is cultured and grown under high copper to biomass conditions. It has been suggested that the role of the McHr is to provide a shuttle to transport dioxygen from the cytoplasm of the cell to the intra-cytoplasmic membranes for consumption by the pMMO. Indeed, McHr enhances the activity of the pMMO when pMMO-enriched membranes are used to assay the enzyme activity. We find that McHr can dramatically improve the activity of pMMO toward the epoxidation of propylene to propylene oxide. The maximum activity is observed at a pMMO to McHr concentration ratio of 4:1, where we have obtained specific activities of 103.7nmol propylene oxide/min/mg protein and 122.8nmol propylene oxide/min/mg protein at 45°C when the turnover is driven by NADH and duroquinol, respectively. These results are consistent with the suggestion that the bacterium requires McHr to deliver dioxygen to the pMMO in the intra-cytoplasmic membranes to accomplish efficient catalysis of methane oxidation when the enzyme is over-expressed in the cells.
authors.affiliation: Department of Chemical Biology, National PingTung University of Education, PingTung, Taiwan. kelvin@mail.npue.edu.tw
authors.forename: Kelvin H-C
authors.initials: KH
authors.lastname: Chen
authors.forename: Hsin-Hui
authors.initials: HH
authors.lastname: Wu
authors.forename: Si-Fu
authors.initials: SF
authors.lastname: Ke
authors.forename: Ya-Ting
authors.initials: YT
authors.lastname: Rao
authors.forename: Chia-Ming
authors.initials: CM
authors.lastname: Tu
authors.forename: Yu-Ping
authors.initials: YP
authors.lastname: Chen
authors.forename: Kuo-Hsuan
authors.initials: KH
authors.lastname: Kuei
authors.forename: Ying-Siao
authors.initials: YS
authors.lastname: Chen
authors.forename: Vincent C-C
authors.initials: VC
authors.lastname: Wang
authors.forename: Wei-Chun
authors.initials: WC
authors.lastname: Kao
authors.forename: Sunney I
authors.initials: SI
authors.lastname: Chan
mesh_terms: D000475:Alkenes / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D055162:Biocatalysis / Q000187:drug effects; D002462:Cell Membrane / Q000187:drug effects / Q000201:enzymology; D002942:Circular Dichroism; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation / Q000187:drug effects; D004852:Epoxy Compounds / Q000378:metabolism; D006422:Hemerythrin / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology*; D006873:Hydroquinones / Q000494:pharmacology; D008565:Membrane Proteins / Q000378:metabolism; D008697:Methane / Q000378:metabolism; D020619:Methylococcus capsulatus / Q000187:drug effects* / Q000201:enzymology; D009243:NAD / Q000494:pharmacology; D010084:Oxidation-Reduction / Q000187:drug effects; D010100:Oxygen / Q000378:metabolism; D010105:Oxygenases / Q000378:metabolism*; D021122:Protein Subunits / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013053:Spectrophotometry
chemical_list: D000475:Alkenes; D001426:Bacterial Proteins; D004852:Epoxy Compounds; D006422:Hemerythrin; D006873:Hydroquinones; D008565:Membrane Proteins; D021122:Protein Subunits; D011994:Recombinant Proteins; D009243:NAD; C013658:propylene; D010105:Oxygenases; C021555:methane monooxygenase; D008697:Methane; C016421:duroquinol; D010100:Oxygen; C009068:propylene oxide