NMR insights into the pre-amyloid ensemble and secretion targeting of the curli subunit CsgA

Sewell, LLSewellStylianou, FisentzosFisentzosStylianouXu, YingqiYingqiXuTaylor, JonathanJonathanTaylorSefer, lealeaSeferMatthews, ststMatthews2020-05-222020-05-222020-05-12Scientific Reports, 2020, 102045-2322http://hdl.handle.net/10044/1/79248The biofilms of Enterobacteriaceae are fortified by assembly of curli amyloid fibres on the cell surface. Curli not only provides structural reinforcement, but also facilitates surface adhesion. To prevent toxic intracellular accumulation of amyloid precipitate, secretion of the major curli subunit, CsgA, is tightly regulated. In this work, we have employed solution state NMR spectroscopy to characterise the structural ensemble of the pre-fibrillar state of CsgA within the bacterial periplasm, and upon recruitment to the curli pore, CsgG, and the secretion chaperone, CsgE. We show that the N-terminal targeting sequence (N) of CsgA binds specifically to CsgG and that its subsequent sequestration induces a marked transition in the conformational ensemble, which is coupled to a preference for CsgE binding. These observations lead us to suggest a sequential model for binding and structural rearrangement of CsgA at the periplasmic face of the secretion machinery.© 2020 The Author(s). This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. Te images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.NMR insights into the pre-amyloid ensemble and secretion targeting of the curli subunit CsgAJournal Articlehttps://www.dx.doi.org/10.1038/s41598-020-64135-9EP/C509463/1ICTRUSTP47774MR/P028225/1