Now, scientists at the University of Michigan have determined the atomic-level, three-dimensional structure of a SEVI precursor known as PAP248-286 and discovered how it damages cell membranes to make them more vulnerable to infection with HIV. The work is described in two new papers.
The most recent, describing the structure, was published online Nov. 17 in the Journal of the American Chemical Society. The paper describing how PAP248-286 interacts with cell membranes appeared in the Nov. 4 issue of Biophysical Journal.
PAP248-286 is a peptide---a chain of amino acids not long enough to be considered a protein. Individual PAP248-286 peptides have a tendency to clump together to form amyloid fibers called SEVI (semen enhancer of viral infection). Amyloid fibers are of great interest because they are the calling cards of many neurodegenerative diseases, such as Alzheimer's and Parkinson's, and aging-related diseases like type-2 diabetes. Using NMR (nuclear magnetic resonance) spectroscopy, a technique that not only yields atomic-level details of a molecule's structure, but also shows how the molecule nestles into the membrane with which it interacts, researcher Ayyalusamy Ramamoorthy and coworkers found that the structure of PAP248-286 is unlike that of most other amyloid-forming peptides and proteins.
In solution, SEVI is completely unstructured or has no definite shape and is therefore ineffective. On the other hand, "when bound to the membrane, it's in a spaghetti-like arrangement---a disorganized, loose coil," said Ramamoorthy, a professor of chemistry and of biophysics. In contrast, most other amyloid proteins assume a more ordered, helical configuration. Also unlike other amyloid peptides, SEVI does not penetrate deep into the greasy region of the cell membrane, but is located near the surface. Ramamoorthy and coauthors believe the spread-out, disordered configuration and its location in the cell membrane may explain the ability of SEVI fibers to enhance HIV infection, as the arrangement provides more surface area with which the virus can interact.
A key finding of the second study is that PAP248-286 "shocks" the membrane, inducing a structural change---a kind of dimple that allows HIV to attach to and enter the cell.
Next, Ramamoorthy and colleagues hope to discern more structural details of PAP248-286 and SEVI. They also plan to screen antioxidant compounds such as green tea extract, curcumin and resveratrol (found in red wine) to see if such compounds are capable of blocking SEVI's HIV-enhancing activity.
Ramamoorthy's coauthors on the Journal of the American Chemical Society paper are graduate student Ravi Nanga, post-doctoral fellows Jeffrey Brender and Nataliya Popovych and NMR specialist Subramanian Vivekanandan. His coauthors on the Biophysical Journal paper are Brender, graduate student Kevin Hartman, former post-doctoral fellow Lindsey Gottler, former graduate student Marchello Cavitt and biophysics undergraduate student Daniel Youngstrom.
This research was supported by funds from the National Institutes of Health.For more information:
Journal of the American Chemical Society paper, NMR Structure in a Membrane Environment Reveals Putative Amyloidogenic Regions of the SEVI Precursor Peptide PAP248-286
Biophysical Journal paper, Helical Conformation of the SEVI Precursor Peptide PAP248-286, a Dramatic Enhancer of HIV Infectivity, Promotes Lipid Aggregation and Fusion
Study suggests possible new target for treating and preventing Alzheimer's
02.12.2016 | Oregon Health & Science University
The first analysis of Ewing's sarcoma methyloma opens doors to new treatments
01.12.2016 | IDIBELL-Bellvitge Biomedical Research Institute
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water
In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...
The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.
Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
02.12.2016 | Medical Engineering
02.12.2016 | Agricultural and Forestry Science
02.12.2016 | Physics and Astronomy