Latest Publications
Membraneless channels sieve cations in ammonia-oxidizing marine archaea
Andriko von Kügelgen, C. Keith Cassidy, Sofie van Dorst, Lennart L. Pagani, Christopher Batters, Zephyr Ford, Jan Löwe, Vikram Alva, Phillip J. Stansfeld & Tanmay A. M. Bharat
Nitrosopumilus maritimus is an ammonia-oxidizing archaeon that is crucial to the global nitrogen cycle. A critical step for nitrogen oxidation is the entrapment of ammonium ions from a dilute marine environment at the cell surface and their subsequent channelling to the cell membrane of N. maritimus. Here we elucidate the structure of the molecular machinery responsible for this process, comprising the surface layer (S-layer), using electron cryotomography and subtomogram averaging from cells. We supplemented our in situ structure of the ammonium-binding S-layer array with a single-particle electron cryomicroscopy structure, revealing detailed features of this immunoglobulin-rich and glycan-decorated S-layer. This in situ structural study illuminates the biogeochemically essential process of ammonium binding and channelling, common to many marine microorganisms that are fundamental to the nitrogen cycle.