The HIV-1 Gag polyprotein precursor composed of the matrix (MA), capsid (CA), nucleocapsid (NC), and p6 domains orchestrates virus assembly via interactions between MA and the cell plasma membrane (PM) on one hand and NC and the genomic RNA on the other hand. As the Gag precursor can adopt a bent conformation, a potential interaction of the NC domain with the PM cannot be excluded during Gag assembly at the PM. To investigate the possible interaction of NC with lipid membranes in the absence of any interference from the other domains of Gag, we quantitatively characterized by fluorescence spectroscopy the binding of the mature NC protein to large unilamellar vesicles (LUVs) used as membrane models. We found that NC, either in its free form or bound to an oligonucleotide, was binding with high affinity (ϳ10 7 M ؊1 ) to negatively charged LUVs. The number of NC binding sites, but not the binding constant, was observed to decrease with the percentage of negatively charged lipids in the LUV composition, suggesting that NC and NC/oligonucleotide complexes were able to recruit negatively charged lipids to ensure optimal binding. However, in contrast to MA, NC did not exhibit a preference for phosphatidylinositol-(4,5)-bisphosphate. These results lead us to propose a modified Gag assembly model where the NC domain contributes to the initial binding of the bent form of Gag to the PM. IMPORTANCEThe NC protein is a highly conserved nucleic acid binding protein that plays numerous key roles in HIV-1 replication. While accumulating evidence shows that NC either as a mature protein or as a domain of the Gag precursor also interacts with host proteins, only a few data are available on the possible interaction of NC with lipid membranes. Interestingly, during HIV-1 assembly, the Gag precursor is thought to adopt a bent conformation where the NC domain may interact with the plasma membrane. In this context, we quantitatively characterized the binding of NC, as a free protein or as a complex with nucleic acids, to lipid membranes and showed that the latter constitute a binding platform for NC. Taken together, our data suggest that the NC domain may play a role in the initial binding events of Gag to the plasma membrane during HIV-1 assembly.T he nucleocapsid protein (NC) of human immunodeficiency virus type 1 (HIV-1) is a small basic nucleic acid binding protein with two strictly conserved CCHC motifs that strongly bind zinc (1). Mature NC results from the protease-mediated cleavage of the Gag polyprotein precursor and plays key roles in HIV-1 replication (2-5). During the early steps, NC acts as a cofactor of the reverse transcriptase (RT), to promote the initiation of reverse transcription (6-8), as well as the two obligatory strand transfers (9, 10). Moreover, NC also reduces RT pauses at the initiation step (11-13), increases the overall RT processivity (14, 15), promotes synthesis through pause sites (16-19), helps to remove the RNA fragments resulting from the RT RNase H activity (20), and may contribute to the pro...

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WSN is a mechanism which is widely deployed for data monitoring in industrial, commercial and many other fields (like military etc.). Many of research have generally focused on making the network feasible and as useful as possible, but in the advent of this the security was given a very less priority and no attention was given to its security. These WSN networks face a wide variety of threats like the wormholes, grey hole attack, message tampering and selective forwarding etc. WSN are mainly attacked by the malicious packet drops. Now talking about the MANET (Mobile Ad hoc Networking) which is defined as the collection of wireless mobile nodes. MANET forms a network without using any of the infrastructures. The algorithm used to overcome this problem is the watchdog algorithm, but the watchdog algorithm has a partial drop problem, in this partial drop problem the attacker can manipulate the packet dropping rate below the threshold. Watchdog does not consider the traffic situations; these situations include congestion and collision. Through this article we have tried to eliminate the drawbacks of the watchdog algorithm. This paper proposes four theories for eliminating drawbacks of the watchdog.