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Published on: October 12, 2018
Morphology-Dependent HIV-Enhancing Effect of Semen-Derived Enhancer of Viral Infection
Xin Qiao1, Jaekyun Jeon1, Amy L Cole2
1Department of Physics, University of Central Florida, Orlando, Florida.
Abstract:
PAP248-286 is a 39-residue fragment (residues 248 to 286) derived from protease cleavage of prostatic acidic phosphatase in semen. The amyloid fibrils formed in vitro by PAP248-286 can dramatically enhance human immunodeficiency virus (HIV) infection. To our knowledge, we present the first report that the HIV-enhancing potency of fibrils formed by PAP248-286 is morphology dependent. We identified pleomorphic fibrils by transmission electron microscopy in two buffer conditions. Our solid-state NMR data showed that these fibrils consist of molecules in distinct conformations. In agreement with NMR, fluorescence measurements confirmed that they are assembled along different pathways, with distinct molecular structures. Furthermore, our cell-based infectivity tests detected distinct HIV-enhancing potencies for fibrils in distinct morphologies. In addition, our transmission electron microscopy and NMR results showed that semen-derived enhancer of viral infection fibrils formed in sodium bicarbonate buffer remain stable over time, but semen-derived enhancer of viral infection fibrils formed in phosphate buffered saline keep evolving after the initial 7 days incubation period. Given time, most of the assemblies in phosphate buffered saline will turn into elongated thin fibrils. They have similar secondary structure but different packing than thin fibrils formed initially after 7 days incubation.
Insights
Amyloid fibrils from semen protein PAP248-286 enhance human immunodeficiency virus (HIV) infection. The study reveals that the fibril
Area of Science:
- Biochemistry
- Structural Biology
- Virology
Background:
- Prostatic acidic phosphatase (PAP) is found in semen.
- A fragment, PAP248-286, forms amyloid fibrils in vitro.
- These fibrils are known to enhance human immunodeficiency virus (HIV) infection.
Purpose of the Study:
- To investigate the morphology-dependent HIV-enhancing potency of PAP248-286 amyloid fibrils.
- To characterize the structural properties and assembly pathways of these fibrils under different buffer conditions.
Main Methods:
- Transmission electron microscopy (TEM) to visualize fibril morphology.
- Solid-state Nuclear Magnetic Resonance (NMR) spectroscopy to determine molecular conformations.
- Fluorescence measurements to study assembly pathways.
- Cell-based infectivity assays to assess HIV enhancement.
Main Results:
- PAP248-286 fibrils exhibit pleomorphic morphologies.
- Distinct fibril morphologies correlate with different molecular conformations and assembly pathways.
- Different fibril morphologies display varying levels of HIV-enhancing potency.
- Fibrils formed in sodium bicarbonate buffer are stable, while those in phosphate-buffered saline evolve over time.
Conclusions:
- The HIV-enhancing capacity of PAP248-286 fibrils is dependent on their morphology and underlying molecular structure.
- Fibril assembly pathways and structural evolution influence their biological activity.
- Understanding these structure-function relationships is crucial for studying semen-derived enhancer of viral infection (SEVI) and HIV transmission.
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