Architecture of the Sap S- layer of Bacillus anthracis revealed by integrative structural biology

• 成果类型: Article
• 署名作者: Sogues, Adria; Leigh, Kendra; Halingstad, Ethan, V; van der Verren, Sander E.; Cecil, Adam J.; Fioravanti, Antonella; Pak, Alexander J.; Kudryashev, Misha; Remaut, Han
• 署名单位: Flanders Institute for Biotechnology (VIB); Vrije Universiteit Brussel; Max Planck Society; Goethe University Frankfurt; Helmholtz Association; Max Delbruck Center for Molecular Medicine; Free University of Berlin; Humboldt University of Berlin; Charite Universitatsmedizin Berlin; Colorado School of Mines; Colorado School of Mines; Colorado School of Mines
• 刊物名称: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
• ISSN/ISSBN: 0027-10849
• DOI: 10.1073/pnas.2415351121
• 发表日期: 2024-12-17
• 关键词: surface-layer; reconstruction; implementation; Visualization; refinement; restraints; RESOLUTION; efficient; software; proteins

摘要

Bacillus anthracis is a spore- forming gram- positive bacterium responsible for anthrax, an infectious disease with a high mortality rate and a target of concern due to bioterrorism and long- term site contamination. The entire surface of vegetative cells in exponential or stationary growth phase is covered in proteinaceous arrays called S- layers, composed of Sap or EA1 protein, respectively. The Sap S- layer represents an important virulence factor and cell envelope support structure whose paracrystalline nature is essential for its function. However, the spatial organization of Sap in its lattice state remains elusive. Here, we employed cryoelectron tomography and subtomogram averaging to obtain a map of the Sap S- layer from tubular polymers that revealed a conformational switch between the postassembly protomers and the previously available X- ray structure of the condensed monomers. To build and validate an atomic model of the lattice within this map, we used a combination of molecular dynamics simulations, X- ray crystallography, cross- linking mass spectrometry, and biophysics in an integrative structural biology approach. The Sap lattice model produced recapitulates a close- to- physiological arrangement, reveals high- resolution details of lattice contacts, and sheds light on the mechanisms underlying the stability of the Sap layer.