The non-structural protein 4B (NS4B) from Hepatitis C virus (HCV) plays a pivotal role in the remodelling of the host cell's membranes, required for the formation of the viral replication complex where genome synthesis occurs. NS4B is an integral membrane protein that possesses a number of domains vital for viral replication. Structural and biophysical studies have revealed that one of these, the second amphipathic N-terminal helix (AH2), plays a key role in these remodelling events. However, there is still limited understanding of the mechanism through which AH2 promotes these changes. Here we report on solid-state NMR and molecular dynamics studies that demonstrate that AH2 promotes the clustering of negatively charged lipids within the bilayer, a process that reduces the strain within the bilayer facilitating the remodelling of the lipid bilayer. Furthermore, the presence of negatively charged lipids within the bilayer appears to promote the disassociation of AH2 oligomers, highlighting a potential role for lipid recruitment in regulating NS protein interactions.

BackgroundThe pathophysiological changes occurring in the trabecular meshwork in primary open angle glaucoma are poorly understood, but are thought to include increased extracellular matrix deposition, trabecular meshwork cell apoptosis, inflammation, trabecular meshwork calcification and altered protein composition of the aqueous humor. Although many proteins are present in aqueous humor, relatively few have been studied extensively, and their potential roles in primary open angle glaucoma are unknown.MethodsAnalyte concentrations in aqueous humor from 19 primary open angle glaucoma and 18 cataract patients were measured using a multiplex immunoassay. Fisher’s exact test was used to assess statistical significance between groups, and correlations of analyte concentrations with age, intraocular pressure, pattern standard deviation, mean deviation, cup-to-disc ratio and disease duration since commencing treatment were tested by Spearman’s method.ResultsCHI3L1, FLRG, HGF, MIF, P-selectin and Uteroglobin were detected in more than 50% of samples of one or both patient groups, some of which have not previously been quantified in aqueous humor. In the glaucoma but not the cataract group, significant correlations were determined with age for Uteroglobin/SCGB1A1 (rs = 0.805, p < 0.0001) and FLRG (rs = 0.706, p = 0.0007). Furthermore, HGF correlated significantly with disease duration (rs = − 0.723, p = 0.0007). There were no differences in analyte concentrations between groups, and no other significant associations with clinical descriptors that passed correction for multiple testing.ConclusionsThe correlations of uteroglobin and FLRG with age in primary open angle glaucoma but not cataract may suggest a heightened requirement for anti-inflammatory (uteroglobin) or anti-calcification (FLRG) activity in the ageing glaucomatous trabecular meshwork.Electronic supplementary materialThe online version of this article (10.1186/s12886-018-0723-4) contains supplementary material, which is available to authorized users.