Dataset Information

Proteomic analysis of monolayer-integrated proteins on lipid droplets identifies amphipathic interfacial ?-helical membrane anchors.

ABSTRACT: Despite not spanning phospholipid bilayers, monotopic integral proteins (MIPs) play critical roles in organizing biochemical reactions on membrane surfaces. Defining the structural basis by which these proteins are anchored to membranes has been hampered by the paucity of unambiguously identified MIPs and a lack of computational tools that accurately distinguish monolayer-integrating motifs from bilayer-spanning transmembrane domains (TMDs). We used quantitative proteomics and statistical modeling to identify 87 high-confidence candidate MIPs in lipid droplets, including 21 proteins with predicted TMDs that cannot be accommodated in these monolayer-enveloped organelles. Systematic cysteine-scanning mutagenesis showed the predicted TMD of one candidate MIP, DHRS3, to be a partially buried amphipathic ?-helix in both lipid droplet monolayers and the cytoplasmic leaflet of endoplasmic reticulum membrane bilayers. Coarse-grained molecular dynamics simulations support these observations, suggesting that this helix is most stable at the solvent-membrane interface. The simulations also predicted similar interfacial amphipathic helices when applied to seven additional MIPs from our dataset. Our findings suggest that interfacial helices may be a common motif by which MIPs are integrated into membranes, and provide high-throughput methods to identify and study MIPs.

SUBMITTER: Pataki CI

PROVIDER: S-EPMC6126764 | biostudies-literature | 2018 Aug

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Proteomic analysis of monolayer-integrated proteins on lipid droplets identifies amphipathic interfacial α-helical membrane anchors.

Pataki Camille I CI Rodrigues João J Zhang Lichao L Qian Junyang J Efron Bradley B Hastie Trevor T Elias Joshua E JE Levitt Michael M Kopito Ron R RR

Proceedings of the National Academy of Sciences of the United States of America 20180813 35

Despite not spanning phospholipid bilayers, monotopic integral proteins (MIPs) play critical roles in organizing biochemical reactions on membrane surfaces. Defining the structural basis by which these proteins are anchored to membranes has been hampered by the paucity of unambiguously identified MIPs and a lack of computational tools that accurately distinguish monolayer-integrating motifs from bilayer-spanning transmembrane domains (TMDs). We used quantitative proteomics and statistical modeli ...[more]

PMID: 30104359

Similar Datasets

Project description:L4F, an alpha helical peptide inspired by the lipid-binding domain of the ApoA1 protein, has potential applications in the reduction of inflammation involved with cardiovascular disease as well as an antioxidant effect that inhibits liver fibrosis. In addition to its biological activity, amphipathic peptides such as L4F are likely candidates to direct the molecular assembly of peptide nanostructures. Here we describe the stabilization of the amphipathic L4F peptide through fusion to a high molecular weight protein polymer. Comprised of multiple pentameric repeats, elastin-like polypeptides (ELPs) are biodegradable protein polymers inspired from the human gene for tropoelastin. Dynamic light scattering confirmed that the fusion peptide forms nanoparticles with a hydrodynamic radius of approximately 50nm, which is unexpectedly above that observed for the free ELP (~5.1nm). To further investigate their morphology, conventional and cryogenic transmission electron microscopy were used to reveal that they are unilamellar vesicles. On average, these vesicles are 49nm in radius with lamellae 8nm in thickness. To evaluate their therapeutic potential, the L4F nanoparticles were incubated with hepatic stellate cells. Stellate cell activation leads to hepatic fibrosis; furthermore, their activation is suppressed by anti-oxidant activity of ApoA1 mimetic peptides. Consistent with this observation, L4F nanoparticles were found to suppress hepatic stellate cell activation in vitro. To evaluate the in vivo potential for these nanostructures, their plasma pharmacokinetics were evaluated in rats. Despite the assembly of nanostructures, both free L4F and L4F nanoparticles exhibited similar half-lives of approximately 1h in plasma. This is the first study reporting the stabilization of peptide-based vesicles using ApoA1 mimetic peptides fused to a protein polymer; furthermore, this platform for peptide-vesicle assembly may have utility in the design of biodegradable nanostructures.

Dataset Information

Proteomic analysis of monolayer-integrated proteins on lipid droplets identifies amphipathic interfacial ?-helical membrane anchors.

Publications

Proteomic analysis of monolayer-integrated proteins on lipid droplets identifies amphipathic interfacial α-helical membrane anchors.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure