A versatile nano display platform from bacterial spore coat proteins.

I-Lin Wu,Jean-Philippe Castaing,Fang Tian,Sriram Subramaniam,Kedar Narayan,Kumaran S Ramamurthi

doi:10.1038/ncomms7777

Abstract

Dormant bacterial spores are encased in a thick protein shell, the ‘coat', which contains ∼70 different proteins. The coat protects the spore from environmental insults, and is among the most durable static structures in biology. Owing to extensive cross-linking among coat proteins, this structure has been recalcitrant to detailed biochemical analysis, so molecular details of how it assembles are largely unknown. Here, we reconstitute the basement layer of the coat atop spherical membranes supported by silica beads to create artificial spore-like particles. We report that these synthetic spore husk-encased lipid bilayers (SSHELs) assemble and polymerize into a static structure, mimicking in vivo basement layer assembly during sporulation in Bacillus subtilis. In addition, we demonstrate that SSHELs may be easily covalently modified with small molecules and proteins. We propose that SSHELs may be versatile display platforms for drugs and vaccines in clinical settings, or for enzymes that neutralize pollutants for environmental remediation.

Highlights

Dormant bacterial spores are encased in a thick protein shell, the ‘coat’, which contains B70 different proteins
Since the behaviour of SpoIVA recruitment and stability in our in vitro system mimicked that of SpoIVA in vivo, we examined the topography of synthetic spore husk-encased lipid bilayers (SSHELs) particles by scanning electron microscopy (SEM) to understand the ultrastructure of the basement layer of the coat
We demonstrated here that we are able to recapitulate the initiation of spore coat assembly atop SSLBs with defined protein components to build what we term SSHEL particles

Summary

Introduction

Dormant bacterial spores are encased in a thick protein shell, the ‘coat’, which contains B70 different proteins. We reconstitute the basement layer of the coat atop spherical membranes supported by silica beads to create artificial spore-like particles. We report that these synthetic spore husk-encased lipid bilayers (SSHELs) assemble and polymerize into a static structure, mimicking in vivo basement layer assembly during sporulation in Bacillus subtilis. Coat assembly begins with the construction of a basement layer, which contains a structural protein termed SpoIVA10 that displays a multi-domain architecture[11]. We reconstitute the basement layer of the spore coat atop spherical lipid bilayers supported by silica beads, using purified SpoIVA protein, and synthesized SpoVM peptide to construct synthetic spore husk-encased lipid bilayers (SSHELs). We propose that decorated SSHELs may be used as a versatile platform for the display of drugs, enzymes and vaccines

Methods

Results

Conclusion