Project description:Methane oxidation by aerobic methanotrophs is well-known to be strongly regulated by the availability of copper, i.e., the “copper-switch”. That is, there are two forms of the methane monooxygenase: a cytoplasmic or soluble methane monooxygenase (sMMO) and a membrane-bound or particulate methane monooxygenase (pMMO). sMMO is only expressed and active in the absence of copper, while pMMO requires copper. Previous work has also shown that one gene in the operon of the soluble methane monooxygenase – mmoD – also plays a critical role, but its function is still vague. Herein we show that MmoD is not needed for expression of genes in the sMMO gene cluster but is critical for formation of sMMO polypeptides and sMMO activity in Methylosinus trichosporium OB3b, indicating that MmoD plays a key post-transcriptional role in maturation of sMMO. Further, data also show that MmoD controls expression of methanobactin, a unique copper-binding compound used by some methanotrophs for copper collection. Collectively these results provide greater insights into the components of the “copper-switch” and thus provide new strategies to manipulate methanotrophic activity.
2023-09-29 | PXD045741 | Pride
Project description:Methane oxidation related microbial diversity on an Arctic shelf
Project description:Proteomics data related to the manuscript with title "Localization of the copper centers in membrane-bound methane monooxygenase by native top-down mass spectrometry"
Project description:The objective of this study was to identify the different functional genes involved in key biogeochemical cycles in thehigh Arctic regions. Understanding the microbial diversity in the Arctic region is an important step to determine the effects of climate change on these areas.
Project description:The objective of this study was to identify the different functional genes involved in key biogeochemical cycles in the low Arctic regions. Understanding the microbial diversity in the Arctic region is an important step to determine the effects of climate change on these areas.
Project description:The objective of this study was to identify the different functional genes involved in key biogeochemical cycles in the sub- Arctic regions. Understanding the microbial diversity in the Arctic region is an important step to determine the effects of climate change on these areas.
Project description:High NH4+ load is known to competitively inhibit bacterial methane oxidation. This is due to a competition between CH4 and NH4+/NH3 for the active site of particulate methane monooxygenase (pMMO), which converts CH4 to CH3OH. Here, we combined growth experiments with global proteomics to elucidate the capability of the methanotroph Methylocystis sp. strain SC2 in acclimatizing to increased NH4+ levels. Our experimental approach also involved amino acid profiling and measurement of NOx compounds. Relative to 1 mM NH4+, high (50 mM and 75 mM) NH4+ load under CH4 replete conditions significantly increased lag phase duration required for proteome adjustment. The proteomic and metabolic responses to increasing ionic and osmotic stress involved significant upregulation of stress-responsive proteins, K+ “salt in” strategy, synthesis of compatible solutes (glutamate and proline), and induction of the glutathione metabolism pathway. A significant increase in the apparent Km value for CH4 oxidation during the growth phase was indicative of increased pMMO-based oxidation of NH4+/NH3 to toxic hydroxylamine. The detoxifying activity of hydroxlyamine oxidoreductase (HAO) led to a significant accumulation of NO2- and, upon decreasing O2 tension, N2O. Putative free intermediate of HAO activity was NO, with NO reductase and hybrid cluster proteins (Hcps) being the candidate enzymes for the reduction of NO to N2O. In summary, strain SC2 has the capacity to precisely rebalance enzymes and osmolyte composition, but the need to simultaneously combat both ionic-osmotic stress and the toxic effects of hydroxylamine may be the reason why its acclimatization capacity is limited to 75 mM NH4+.