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Characterization of the Copper Starvation Response in the pMMO-Obligate Methanotrophic Bacterium Methylomicrobium album strain BG8
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- Author / Creator
- Sun, Phillip K
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Studies on copper as a critical nutrient in methane-oxidizing bacteria (MOB) have mostly focused on the well-characterized “copper switch” in species with dual methane monooxygenase (MMO) variants (Takeguchi & Okura, 2000, Knapp et al., 2007, Kenney et al., 2016). Copper availability dictates which of the two analogous MMO enzymes is used: copper sufficiency favors expression of the copper-associated particulate methane monooxygenase (pMMO) whereas copper depletion favors the iron-associated soluble methane monooxygenase (sMMO) to catalyze the oxidation of methane into methanol (Miyaji et al., 2019, Chang et al., 2021). However, only some MOB, mostly Alphaproteobacteria (alpha-MOB), encode sMMO (Takeguchi & Okura, 2000, Fru et al., 2011), while the majority of Gammaproteobacteria MOB (gamma-MOB) are pMMO-obligate and lack a “copper switch”; thus, their response to copper starvation has not been as well studied. Under copper deficiency, some MOB produce methanobactin (Mbn), a chalkophore used for scavenging copper from the environment (Fru et al., 2011, Bandow et al., 2012). While Mbn and their respective biosynthetic gene clusters (BGCs) have been well described in alpha-MOB (Semrau et al., 2020), only recently have Mbn been minimally characterized in gamma-MOB (Choi et al., 2010, Kang-Yun et al., 2022). How pMMO-obligate gamma-MOB respond to copper starvation stress represents a gap in our state of knowledge. This study examines the copper starvation response in the gamma-MOB, pMMO-obligate, Methylomicrobium album strain BG8, which was shown to produce a chalkophore under copper limitation (Kang-Yun et al., 2022). M. album BG8 grown under copper deficiency exhibited stunted growth and a smaller cell size; and transcriptomic analysis revealed the shutting down of metabolic activity with selective upregulation of copper acquisition genes. Bioinformatics analysis via a suite of BGC detection and phylogenetic programs reveal a downregulated BGC encoding for siderophore biosynthesis, as well as two intensively upregulated cyanobacterial-related BGCs potentially encoding for a putative Mbn, and a putative ‘toxin’ hereby named methanopeptide (Mpt). Taken together, these results reveal novel natural products involved in alleviating copper starvation stress, underscore the redundant nature of copper acquisition systems in the pMMO-obligate M. album BG8, and establish an evolutionary connection in a stress response system between MOB and cyanobacteria.
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- Graduation date
- Spring 2024
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- Type of Item
- Thesis
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- Degree
- Master of Science
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- License
- This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.