Abstract:
:In previous in vivo studies, amyloid fibers formed from a peptide ubiquitous in human seminal fluid (semen-derived enhancer of viral infection (SEVI)) were found to dramatically enhance the infectivity of the HIV virus (3-5 orders of magnitude by some measures). To complement those studies, we performed in vitro assays of PAP(248-286), the most active precursor to SEVI, and other polycationic polymers to investigate the physical mechanisms by which the PAP(248-286) promotes the interaction with lipid bilayers. At acidic (but not at neutral) pH, freshly dissolved PAP(248-286) catalyzes the formation of large lipid flocculates in a variety of membrane compositions, which may be linked to the promotion of convective transport in the vaginal environment rather than transport by a random Brownian motion. Furthermore, PAP(248-286) is itself fusiogenic and weakens the integrity of the membrane in such a way that may promote fusion by the HIV gp41 protein. An alpha-helical conformation of PAP(248-286), lying parallel to the membrane surface, is implicated in promoting bridging interactions between membranes by the screening of the electrostatic repulsion that occurs when two membranes are brought into close contact. This suggests that nonspecific binding of monomeric or small oligomeric forms of SEVI in a helical conformation to lipid membranes may be an additional mechanism by which SEVI enhances the infectivity of the HIV virus.
journal_name
Biophys Jjournal_title
Biophysical journalauthors
Brender JR,Hartman K,Gottler LM,Cavitt ME,Youngstrom DW,Ramamoorthy Adoi
10.1016/j.bpj.2009.08.034subject
Has Abstractpub_date
2009-11-04 00:00:00pages
2474-83issue
9eissn
0006-3495issn
1542-0086pii
S0006-3495(09)01394-0journal_volume
97pub_type
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