Keep up to date with the latest research and developments from Diamond. Sign up for news on our scientific output, facility updates and plans for the future.
Climate change is mostly caused by the release of ‘greenhouse gases’ – gases in the Earth's atmosphere that trap heat and stop it escaping into space, acting as a warming blanket around the Earth, known as the 'greenhouse effect'. Methane is a greenhouse gas whose concentration in the atmosphere is currently around two-and-a-half times greater than pre-industrial levels and is increasing steadily1. This rise has important implications for climate change.
Methanotrophs are methane-oxidising bacteria that play a central role in greenhouse gas mitigation and have potential applications in biomanufacturing. Particulate methane monooxygenase (pMMO) is the main membrane-bound enzyme used by methanotrophs to oxidise methane.
Because it is a membrane metalloenzyme, the methane oxidation activity of pMMO is sensitive to solubilisation and removal from the membrane. From whole cells to isolated membranes, catalytic activity decreases by 5-10-fold, and upon solubilisation in detergent, there is a further 10-fold reduction in activity with no measurable activity for crystallised samples. To fully understand how the enzyme functions, it is important to study it in its native environment, in its most active state in the cell, rather than in soluble single particle or crystal form.
A team of scientists used cryo-electron tomography (cryo-ET) to determine the structure of pMMO in its native membrane to 4.8 Å resolution. Data was collected at Diamond’s electron Bio-Imaging Centre (eBIC) using the 300kv Titan Krios microscope with technical support from staff scientists at eBIC. The data revealed lipid-stabilised features and a higher-order hexagonal array arrangement in intact cells. Array formation correlates with increased enzymatic activity, highlighting the importance of studying the enzyme in its native environment.
The remarkable hexagonal arrays of pMMO trimers provide new insights into the impact of higher-order packing on the enzymatic activity of pMMO in native cells. Understanding how pMMO arrays assemble and promote methane oxidation will be integral to future efforts to deploy methanotrophs in biotechnology. The findings also demonstrate the power of cryo-ET to structurally characterise native membrane enzymes in the cellular context.
Zhu Y. et al. Structure and Activity of Particulate Methane Monooxygenase Arrays in Methanotrophs. Nature Communications (2022). DOI: 10.1038/s41467-022-32752-9
Electron microscope Titan Krios at the electron Bio-Imaging Centre (eBIC).
NT21004 & NT29812.
Diamond press office: Isabelle Boscaro-Clarke, Head of Communications, firstname.lastname@example.org
Cryo-EM: Daniel Clare, Principal Electron Microscopy Scientist on eBIC, Diamond Light Source, email@example.com
Corresponding author: Yanan Zhu, Post Doctoral Research Associate, University of Oxford Division of Structural Biology, firstname.lastname@example.org
Diamond Light Source is the UK's national synchrotron science facility, located at the Harwell Science and Innovation Campus in Oxfordshire.
Copyright © 2022 Diamond Light Source
Diamond Light Source Ltd
Harwell Science & Innovation Campus
Diamond Light Source® and the Diamond logo are registered trademarks of Diamond Light Source Ltd
Registered in England and Wales at Diamond House, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE, United Kingdom. Company number: 4375679. VAT number: 287 461 957. Economic Operators Registration and Identification (EORI) number: GB287461957003.