Virology Faculty Member - Alan Engelman

Alan Engelman

Professor of Medicine

Dana-Farber Cancer Institute
Department of Cancer Immunology and AIDS
450 Brookline Ave./3 Blackfan Circle, CLS 1013
Boston, MA 02215
Tel: 617-632-4361
Fax: 617-632-4338
Email: alan_engelman@dfci.harvard.edu



Research in my laboratory focuses on the integration of retroviral reverse transcripts into cell chromosomes, a key step in viral replication. Host cell proteins in addition to the viral integrase (IN) play essential roles in integration. IN functions in the context of preintegration complexes (PICs) that contain the vDNA, host cell, and other viral proteins.

PICs isolated from infected cells catalyze vDNA integration in vitro. Although work with purified IN proteins has revealed details of IN structure and function, little is known about the organization and structure of PICs. We previously defined the HIV-1 intasome as the nucleoprotein complex within PICs that mediates integration. Current projects focus on defining the stoichiometries and functional organization of viral and cell proteins in purified PICs. In vivo roles of host cell factors are evaluated using RNAi and gene knockout strategies. Biochemical approaches are used to reconstitute retroviral intasomes for structure determination by x-ray crystallography.

One cell protein that directly binds to HIV-1 IN, lens epithelium-derived growth factor (LEDGF)/p75, stimulates recombinant IN activity in vitro. LEDGF/p75 was knocked out in mice to generate a clean ex vivo model system. HIV-1 titer was reduced significantly, revealing a crucial role for LEDGF/p75 in infection. Different retroviruses differentially target genomic features like genes and promoter regions during integration – lentiviruses such as HIV-1 favor the bodies of active genes. Global integration was reduced approximately tenfold by LEDGF/p75 depletion, with significant redistributions of residual proviruses to gene-poor regions and transcriptional start sites, mimicking the natural distributions of other retroviruses. A new class of allosteric IN inhibitors (ALLINIs) that compete with LEDGF/p75 for binding to IN inhibit integration by inducing premature enzyme multimerization, which precludes IN-vDNA assembly. ALLINIs were unexpectedly found to inhibit the formation of the electron-dense HIV-1 core during the late stage of virus replication. Hypersensitivity of IN to multimer-inducing compounds during HIV-1 production highlights a novel mechanism of action for exploitation in clinical ALLINI development.



Last Update: 10/22/2013



Publications

For a complete listing of publications click here.

 


 

Ferris AL, Wu X, Hughes CM, Stewart C, Smith SJ, Milne TA, Wang GG, Shun MC, Allis CD, Engelman A, Hughes SH. Lens epithelium-derived growth factor (LEDGF) fusion proteins redirect HIV-1 DNA integration. Proc Natl Acad Sci U S A 2010; 107:3135-40.

Hare S, Gupta SS, Valkov E, Engelman A, Cherepanov P. Retroviral intasome assembly and inhibition of DNA strand transfer. Nature 2010; 464:232-6.

Krishnan L, Li X, Naraharisetty HL, Hare S, Cherepanov P, Engelman A. Structure-based modeling of the functional HIV-1 intasome and its inhibition. Proc Natl Acad Sci U S A 2010; 107:15910-5.

Wang H, Jurado KA, Wu X, Shun MC, Li X, Ferris AL, Smith SJ, Patel PA, Fuchs JR, Cherepanov P, Kvaratskhelia M, Hughes SH, Engelman A. HRP2 determines the efficiency and specificity of HIV-1 integration in LEDGF/p75 knockout cells but does not contribute to the antiviral activity of a potent LEDGF/p75-binding site integrase inhibitor. Nucleic Acids Res 2012; 40:11518-30.

Jurado KA, Wang H, Slaughter A, Feng L, Kessl JJ, Koh Y, Wang W, Ballandras-Colas A, Patel PA, Fuchs JR, Kvaratskhelia M, Engelman A. Allosteric integrase potency is determined through the inhibition of HIV-1 particle maturation. Proc Natl Acad Sci U S A 2013; in press.



© 2013 by the President and Fellows of Harvard College