Effect of Cholesterol on Membrane Partitioning Dynamics of Hepatitis A Virus-2B peptide

Abstract

Understanding the viral peptide detection, partitioning and subsequent host membrane composition-based response is required for gaining insights into viral mechanism. Here, we probe the crucial role of presence of membrane lipid packing defects, depending on the membrane composition, in allowing the viral peptide belonging to C-terminal Hepatitis A Virus-2B (HAV-2B) to detect, attach and subsequently partition into the host cell membrane mimics. We conclusively show that the hydrophobic residues in the viral peptide detect the transiently present lipid packing defects, insert themselves into such defects, form anchor points and facilitate the partitioning of the peptide. We also show that the presence of cholesterol significantly alters such lipid packing defects, both in size and in number, thus mitigating the partitioning of the membrane active viral peptide into cholesterol-rich membranes. These results show differential ways in which presence and absence of cholesterol can alter the permeability of the host membranes to the membrane active viral peptide component of HAV-2B virus, via lipid packing defects, and can possibly be a part of general membrane detection mechanism for the viroporin class of viruses.

Role of Disulfide Bonds in Membrane Partitioning of a Viral Peptide

“…The MD simulation of disulfide free HAV-2B peptide in water from our previous study [40], indicate close spatial proximity of cysteine residues, namely C11, C47 and C52, which may favour formation of possible SS-bonded states of the peptide denoted as SS11-47, SS11-52 and SS47-52. The distribution of pairwise SS-distance of disulfide free HAV-2B peptide in water (see SI, Fig S1) is multi-modal with several peaks spread between 3 Å and 20 Å.…”

“…These cysteine residues may remain in reduced thiol state or in oxidized state, where two such residues are bonded through a disulfide linkage, resulting in three possible SS-bonded states of HAV-2B peptide denoted as SS11-47, SS11-52 and SS47-52. Owing to unavailability of experimentally determined structure, the membrane active region of HAV-2B peptide has been modelled in a recent study [39] and further refined through extensive molecular dynamics (MD) simulations in water, details of which are provided in our earlier study [40]. [46], MEMBPLUGIN [47], Packmem [48] and in-house Fortran codes.…”

“…Our previous study indicated that the SS-free HAV-2B peptide senses membrane topography in the form of lipid packing defects, inserts into such defects and subsequently partitions into POPC bilayer. [40] In this section, we elucidate the mechanism of partitioning of SS47-52 state of the viral peptide. We consider a representative set of residues, C11 (red), L18…”

“…Experimental demonstrations based on biophysical techniques and biochemical assays in membrane mimicking conditions indicated an   helical conformation exhibiting lipid type and composition dependent membrane permeabilizing property. [39] In our previous study [40] based on extensive all-atom MD simulations, we provided insight into HAV-2B peptide induced membrane response as a function of lipid type and composition. The simulations elucidated how the SS-free state of the peptide could sense membrane topography in the form of lipid packing defects and subsequently partitioned into model POPC bilayer, thereby inducing membrane destabilization.…”