Molecular dynamics and machine learning stratify motion-dependent activity profiles of S-layer destabilizing nanobodies.

Nanobody (Nb)-induced disassembly of surface array protein (Sap) S-layers, a two-dimensional paracrystalline protein lattice from , has been presented as a therapeutic intervention for lethal anthrax infections. However, only a subset of existing Nbs with affinity to Sap exhibit depolymerization activity, suggesting that affinity and epitope recognition are not enough to explain inhibitory activity. In this study, we performed all-atom molecular dynamics simulations of each Nb bound to the Sap binding site and trained a collection of machine learning classifiers to predict whether each Nb induces depolymerization.

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

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.

SlyB encapsulates outer membrane proteins in stress-induced lipid nanodomains.

The outer membrane in Gram-negative bacteria consists of an asymmetric phospholipid-lipopolysaccharide bilayer that is densely packed with outer-membrane β-barrel proteins (OMPs) and lipoproteins. The architecture and composition of this bilayer is closely monitored and is essential to cell integrity and survival. Here we find that SlyB, a lipoprotein in the PhoPQ stress regulon, forms stable stress-induced complexes with the outer-membrane proteome.