Stability and Shape of Hepatitis B Virus Capsids In Vacuo

Abstract

The hepatitis B virus (HBV) is a major cause of liver disease in humans [1] and its non-infectious capsid is of interest for nanotechnology, including for drug-delivery applications. A precise biophysical characterization of these particles is of importance not only for these applications, but also because it may provide further insight into the replication cycle and assembly pathway of the virus, and thus contribute to the future development of drugs. [2,3] The HBV capsid protein (cp) forms icosahedral capsids of two sizes in vivo and in vitro (with triangulation numbers of T = 3 and T = 4 [4] that contain 180 and 240 subunits, respectively [5][6][7][8] ). The capsid protein has two domains-a core domain (amino acids 1-140) and a "protamine domain" (amino acids 150-183)-connected by a 10-residue linker; [9] of these, the core domain is necessary and sufficient for assembly of the capsid. The length of the linker and the conditions under which assembly take place determine the ratio of the T = 3 and T = 4 capsids obtained.

Mass spectrometric methods to analyze the structural organization of macromolecular complexes

“…Calibrants, with their collision cross-sections obtained by LDT IMS-MS, are required to relate the drift time values to collision cross-sections. Combined with computational approaches [88][89][90], IMS-MS has been extensively applied to study macromolecular assemblies [91][92][93][94].…”

Structure, stability and dynamics of norovirus P domain derived protein complexes studied by native mass spectrometry

“…Argon was used as background gas in both the trap and transfer T-Wave cells at a flow rate of 3 mL/min with applied collision voltages of 10 and 12 V, respectively. Nitrogen was used in the ion mobility (IM) cell for separation of ions by their mobility at a flow rate of 25 mL/min, a velocity of 250 m/s and ramped waveheight of 6-19 V. Collisional cross-sections (CSSs) were determined using the experimentally measured IM drift times and through calibration using proteins of known cross sections (Clemmer, 2008) as described previously (Ruotolo et al, 2008;Uetrecht et al, 2008a). Reported CCS values are anaverage of the measurementsacross the charge state distribution for a given oligomeric species.…”

“…Native mass spectrometry has emerged as a valuable technique for protein complex characterisation in terms of molecular weights, stoichiometry and protein complex structures. Application of this methodology to a wide variety of challenging projects, including viral particles (Shoemaker et al, 2010;Uetrecht et al, 2008aUetrecht et al, , 2008b, heterogeneous protein assemblies (Aquilina et al, 2003;van Duijn et al, 2005) and membrane bound protein assemblies (Barrera et al, 2009), has indicated that many aspects of the topology of large noncovalent protein complexes can be preserved in the gas phase.…”

Ion Mobility‐Mass Spectrometry

“…(12,13) These complexes have higher order tertiary and quaternary structures and dynamic binding events which are only partially understood with traditional biological and other analytical techniques, such as nuclear magnetic resonance and X-ray crystallography. IMS-MS applications of protein complexes have led to a better understanding of oligomeric tryptophan RNA binding attenuation protein complexes, (148) Hepatitis B virus capsids which are 3-4 MDa in size, (149) and GroEL chaperone systems in Escherichia coli, (156) to name a few. Much of the understanding of small inorganic systems to large biological systems with IMS-MS is made possible through computer modeling algorithms which give insight into shapes and sizes of molecules measured with experimental collision cross-sections.…”