Identification of amino acid residues critical for the B cell growth-promoting activity of HIV-1 matrix protein p17 variants
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Date
2019Journal
Biochimica et Biophysica Acta - General SubjectsPublisher
Elsevier B.V.Type
Article
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Background: HIV-1 matrix protein p17 variants (vp17s) detected in HIV-1-infected patients with non-Hodgkin's lymphoma (HIV-NHL) display, differently from the wild-type protein (refp17), B cell growth-promoting activity. Biophysical analysis revealed that vp17s are destabilized as compared to refp17, motivating us to explore structure-function relationships. Methods: We used: biophysical techniques (circular dichroism (CD), nuclear magnetic resonance (NMR) and thermal/GuHCL denaturation) to study protein conformation and stability; Surface plasmon resonance (SPR) to study interactions; Western blot to investigate signaling pathways; and Colony Formation and Soft Agar assays to study B cell proliferation and clonogenicity. Results: By forcing the formation of a disulfide bridge between Cys residues at positions 57 and 87 we obtained a destabilized p17 capable of promoting B cell proliferation. This finding prompted us to dissect refp17 to identify the functional epitope. A synthetic peptide (F1) spanning from amino acid (aa) 2 to 21 was found to activate Akt and promote B cell proliferation and clonogenicity. Three positively charged aa (Arg15, Lys18 and Arg20) proved critical for sustaining the proliferative activity of both F1 and HIV-NHL-derived vp17s. Lack of any interaction of F1 with the known refp17 receptors suggests an alternate one involved in cell proliferation. Conclusions: The molecular reasons for the proliferative activity of vp17s, compared to refp17, relies on the exposure of a functional epitope capable of activating Akt. General significance: Our findings pave the way for identifying the receptor(s) responsible for B cell proliferation and offer new opportunities to identify novel treatment strategies in combating HIV-related NHL. © 2018 The Author(s)Identifier to cite or link to this item
https://www.scopus.com/inward/record.uri?eid=2-s2.0-85054073158&doi=10.1016%2fj.bbagen.2018.09.016&partnerID=40&md5=89121da0dcb363c00b7dc6427039da0d; http://hdl.handle.net/10713/8693ae974a485f413a2113503eed53cd6c53
10.1016/j.bbagen.2018.09.016