Victoria D'Souza, PhD
Department of Molecular and Cellular Biology, Faculty of Arts and Sciences
Structural biology of retroviruses
The D’Souza laboratory investigates the structural basis of retroviral replication, including the initiation of reverse transcription and translation of viral genes. Understanding the structural determinants of these fundamental processes of the retroviral life cycle is vital for
Retroviruses like HIV and MoMLV are associated with a wide range of clinical diseases, including leukemia, tumors, and acquired immunodeficiency syndrome. The D’Souza laboratory focuses on the structural determinants of retroviral replication, including reverse transcription and gene translation. Although some aspects of reverse transcription and gene expression in retroviruses have received considerable attention, especially with an eye towards potential antiviral therapeutics development, understanding the precise mechanisms that promote or regulate these steps and elucidating the detailed and complex structures formed during these processes could result in novel and superior drug candidates.
Current Research Interests
- Discovering the structural basisof retroviral replication using Nuclear Magnetic Resonance (NMR) and other biophysical and biochemical methods.
- Investigating the structural determinants underlying the basic mechanism of reverse transcription in retroviruses. Specifically, studying primer placement and the initiation of reverse transcription complex formation.
- Elucidating the solution structure and mechanisms of retroviral read-through translation, including correct polypeptide ratio assurance.
Tools and Assays
· Nuclear Magnetic Resonance (NMR)
· Cryo-Electron Tomography
· Structural analysis
· Structure-based drug discovery
The D’Souza laboratory has been applying Nuclear Magnetic Resonance (NMR) and other biophysical and biochemical methods to investigate the structural basis of retroviral replication. Following Dr. D’Souza’s initial breakthrough with the structural resolution of the encapsidation signal (an 101-nucleotide RNA) during murine leukemia virus (MLV) genome packaging, the lab is now focused on understanding other structural aspects of retroviral replication.
The laboratory has recently elucidated the solution structure of stem-loop 4 of human 7SK small nuclear RNA (snRNA) in complex with arginine. The 7SK snRNA is a highly conserved non-coding RNA that regulates transcriptional elongation by RNA Polymerase II (Pol II). These findings represent the first high-resolution structural dataset for/snapshot of a key regulatory RNA, and complement the recent characterization of protein structures within other snRNP complexes, including Human Immune Deficiency Virus 1 (HIV-1) TAR RNA. Because this 7SK snRNA shares a functional and structural homology with the HIV-1 regulatory transactivation response region (TAR) RNA, Dr. D’Souza’s data not only demonstrate sequence conservation, but also reveal motifs that may play a role in the recognition of cellular proteins P-TEFb and HEXIM, as well as the recognition of the HIV-1Tat protein, which has evolved to mimic these cellular proteins. These findings further highlight the role of RNA structure in RNA-protein recognition and provide a basis for understanding the differential binding of Tat to 7SK and HIV-1 TAR RNA –information which could be utilized in the development of potential antiviral therapeutics.
The D’Souza laboratory also has recently elucidated the structure of a conserved retroviral RNA element that is required for genome packaging in the Moloney Murine Leukemia Virus (MoMLV), using NMR Spectroscopy and Cryo-Electron Tomography. These findings are not only a tremendous achievement for fundamental virology, but also carry profound implications for the development of retroviral vectors used in gene therapy. Further, MoMLV belongs to a family of viruses that include human pathogenic viruses implicated in prostate cancer and chronic fatigue syndrome, so these structural studies could be potentially utilized for therapeutic strategies.