
==== Front
bioRxiv
BIORXIV
bioRxiv
2692-8205
Cold Spring Harbor Laboratory

10.1101/2024.09.05.611363
preprint
1
Article
Cryo-EM structure and polar assembly of the PS2 S-layer of Corynebacterium glutamicum
Sogues Adrià http://orcid.org/0000-0002-5752-6009

Sleutel Mike http://orcid.org/0000-0003-3247-2187

Petit Julienne
Megrian Daniela
Bayan Nicolas
Wehenkel Anne Marie
Remaut Han http://orcid.org/0000-0002-9775-4102

05 9 2024
2024.09.05.611363https://creativecommons.org/licenses/by-nc-nd/4.0/ This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which allows reusers to copy and distribute the material in any medium or format in unadapted form only, for noncommercial purposes only, and only so long as attribution is given to the creator.
http://biorxiv.org/lookup/doi/10.1101/2024.09.05.611363
nihpp-2024.09.05.611363.pdf
Abstract

The polar-growing Corynebacteriales have a complex cell envelope architecture characterized by the presence of a specialized outer membrane composed of mycolic acids. In some Corynebacteriales, this mycomembrane is further supported by a proteinaceous surface layer or ‘S-layer’, whose function, structure and mode of assembly remain largely enigmatic. Here, we isolated ex vivo PS2 S-layers from the industrially important Corynebacterium glutamicum and determined its atomic structure by 3D cryoEM reconstruction. PS2 monomers consist of a six-helix bundle ‘core’, a three-helix bundle ‘arm’, and a C-terminal transmembrane (TM) helix. The PS2 core oligomerizes into hexameric units anchored in the mycomembrane by a channel-like coiled-coil of the TM helices. The PS2 arms mediate trimeric lattice contacts, crystallizing the hexameric units into an intricate semipermeable lattice. Using pulse-chase live cell imaging, we show that the PS2 lattice is incorporated at the poles, coincident with the actinobacterial elongasome. Finally, phylogenetic analysis shows a paraphyletic distribution and dispersed chromosomal location of PS2 in Corynebacteriales as a result of multiple recombination events and losses. These findings expand our understanding of S-layer biology and enable applications of membrane-supported self-assembling bioengineered materials.
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pmc
