Open AccessStructural Characterization of a Synthetic Tandem-Domain Bacterial Microcompartment Shell Protein Capable of Forming Icosahedral Shell Assemblies
Author(s) -
Markus Sutter,
Sean McGuire,
Bryan Ferlez,
Cheryl A. Kerfeld
Publication year - 2019
Publication title -
acs synthetic biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.156
H-Index - 66
ISSN - 2161-5063
DOI - 10.1021/acssynbio.9b00011
Subject(s) - random hexamer , pentamer , icosahedral symmetry , protein engineering , linker , shell (structure) , chemistry , biophysics , nanotechnology , enzyme , biology , biochemistry , materials science , crystallography , computer science , composite material , operating system
Bacterial microcompartments are subcellular compartments found in many prokaryotes; they consist of a protein shell that encapsulates enzymes that perform a variety of functions. The shell protects the cell from potentially toxic intermediates and colocalizes enzymes for higher efficiency. Accordingly, it is of considerable interest for biotechnological applications. We have previously structurally characterized an intact 40 nm shell comprising three different types of proteins. One of those proteins, BMC-H, forms a cyclic hexamer; here we have engineered a synthetic protein that consists of a tandem duplication of BMC-H connected by a short linker. The synthetic protein forms cyclic trimers that self-assemble to form a smaller (25 nm) icosahedral shell with gaps at the pentamer positions. When coexpressed in vivo with the pentamer fused to an affinity tag we can purify complete icosahedral shells. This engineered shell protein constitutes a minimal shell system to study permeability; reducing symmetry from 6- to 3-fold will allow for finer control of the pore environment. We have determined a crystal structure of this shell to guide rational engineering of this microcompartment shell for biotechnological applications.