Lanthanide (Ln) elements are utilized as cofactors for catalysis by XoxF-type methanol dehydrogenases (MDHs). A primary assumption is that XoxF enzymes produce formate from methanol oxidation, which could impact organisms that require formaldehyde for assimilation. We report genetic and phenotypic evidence showing that XoxF1 (MexAM1_1740) from
- Award ID(s):
- 2027113
- PAR ID:
- 10357599
- Date Published:
- Journal Name:
- Frontiers in Microbiology
- Volume:
- 13
- ISSN:
- 1664-302X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Methylobacterium extorquens AM1 produces formaldehyde, and not formate, during growth with methanol. Enzyme purified with lanthanum or neodymium oxidizes formaldehyde. However, formaldehyde oxidation via 2,6-dichlorophenol-indophenol (DCPIP) reduction is not detected in cell-free extracts from wild-type strain methanol- and lanthanum-grown cultures. Formaldehyde activating enzyme (Fae) is required for Ln methylotrophic growth, demonstrating that XoxF1-mediated production of formaldehyde is essential. Addition of exogenous lanthanum increases growth rate with methanol by 9–12% but does not correlate with changes to methanol consumption or formaldehyde accumulation. Transcriptomics analysis of lanthanum methanol growth shows upregulation ofxox1 and downregulation ofmxa genes, consistent with the Ln-switch, no differential expression of formaldehyde conversion genes, downregulation of pyrroloquinoline quinone (PQQ) biosynthesis genes, and upregulation offdh4 formate dehydrogenase (FDH) genes. Additionally, the Ln-dependent ethanol dehydrogenase ExaF reduces methanol sensitivity in thefae mutant strain when lanthanides are present, providing evidence for the capacity of an auxiliary role for ExaF during Ln-dependent methylotrophy. -
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