Related Experiment Video
Updated: Aug 8, 2026
Peptide-based Identification of Functional Motifs and their Binding Partners
Published on: July 1, 2013
Human immunodeficiency virus type 1 Nef binds directly to Lck and mitogen-activated protein kinase, inhibiting kinase
1AIDS Cellular Biology Unit, Macfarlane Burnet Centre for Medical Research, Fairfield, Victoria, Australia.
Insights
The HIV-1 Nef protein interacts with Lck and MAPK kinases, inhibiting their activity. This interaction disrupts T-cell signaling, promoting viral replication and disease progression.
Area of Science:
- Molecular Biology
- Virology
- Immunology
Background:
- Human immunodeficiency virus type I (HIV-1) Nef protein is crucial for disease pathogenesis.
- Nef augments viral replication and impairs T-cell function.
- Nef's effects on host cells may involve interactions with signaling proteins.
Purpose of the Study:
- To investigate the molecular mechanisms by which HIV-1 Nef interacts with cellular signaling proteins.
- To identify the specific domains involved in the Nef-Lck and Nef-MAPK interactions.
- To determine the effect of Nef on the kinase activity of Lck and MAPK.
Main Methods:
- Recombinant Nef protein was used in coprecipitation and binding assays with purified Lck and MAPK.
- Synthetic peptides corresponding to Nef's proline-rich repeat [(Pxx)4] were used to map interaction domains.
- In vitro kinase assays were performed to assess the activity of Lck and MAPK in the presence of Nef.
Main Results:
- Nef directly interacted with Lck and MAPK.
- The proline-rich repeat [(Pxx)4] motif (residues 69-78) of Nef was identified as a key binding site for Lck's SH3 domain and also bound MAPK.
- Nef significantly inhibited the in vitro kinase activity of both Lck and MAPK.
Conclusions:
- HIV-1 Nef binds to Lck and MAPK via its proline-rich repeat motif.
- Nef's inhibition of Lck and MAPK kinase activity disrupts T-cell receptor signaling pathways.
- These molecular interactions contribute to altered T-cell function, enhanced viral replication, and HIV-1 pathogenesis.
Abstract:
It is now well established that human immunodeficiency virus type I (HIV-1) Nef contributes substantially to disease pathogenesis by augmenting virus replication and markedly perturbing T-cell function. The effect of Nef on host cell activation could be explained in part by its interaction with specific cellular proteins involved in signal transduction, including at least a member of the src family kinase, Lck, and the serine/threonine kinase, mitogen-activated protein kinase (MAPK). Recombinant Nef directly interacted with purified Lck and MAPK in coprecipitation experiments and binding assays. A proline-rich repeat sequence [(Pxx)4] in Nef occurring between amino acid residues 69 to 78 is highly conserved and bears strong resemblance to a defined consensus sequence identified as an SH3 binding domain present in several proteins which can interact with the SH3 domain of various signalling and cytoskeletal proteins. Binding and coprecipitation assays with short synthetic peptides corresponding to the proline-rich repeat sequence [(Pxx)4] of Nef and the SH2, SH3, or SH2 and SH3 domains of Lck revealed that the interaction between these two proteins is at least in part mediated by the proline repeat sequence of Nef and the SH3 domain of Lck. In addition to direct binding to full-length Nef, MAPK was also shown to bind the same proline repeat motif. Nef protein significantly decreased the in vitro kinase activity of Lck and MAPK. Inhibition of key members of signalling cascades, including those emanating from the T-cell receptor, by the HIV-1 Nef protein undoubtedly alters the ability of the infected T cell to respond to antigens or cytokines, facilitating HIV-1 replication and contributing to HIV-1-induced disease pathogenesis.
