Proteomic profiling identifies the SIM-associated complex of KSHV-encoded LANA

Area of Science:

• Virology
• Molecular Biology
• Proteomics

Background:

• Kaposi's sarcoma-associated herpesvirus (KSHV) latency-associated nuclear antigen (LANA) is crucial for viral episome maintenance, DNA replication, and tumorigenesis.
• LANA's role in regulating host cell SUMOylation, leading to chromatin silencing, has been suggested.
• Understanding LANA protein's broader effects on host gene expression is essential for KSHV pathogenesis research.

Purpose of the Study:

• To identify cellular proteins interacting with the SUMO interacting motif (SIM) of LANA (LANA(SIM)) using mass spectrometry (MS).
• To investigate the role of SUMOylation in LANA-mediated host gene regulation and its implications for KSHV.
• To propose a model for the LANA(SIM) regulatory circuit involving SUMOylation.

Main Methods:

• Utilized MS/MS analysis to identify proteins associated with LANA(SIM).
• Compared proteomic data with previous analyses of LANA mutants (LANA(NC)).
• Performed cluster and pathway analysis to elucidate regulatory networks.

Main Results:

• Identified 151 proteins associated with LANA(SIM), including a complex with high SUMOylation and SIM motifs.
• Confirmed higher affinity of LANA(SIM) with SUMO-2 modified isoforms compared to SUMO-1, with KAP1 as a key component.
• Proposed a model for LANA(SIM) regulatory circuit involving SUMOylation of cell cycle, DNA replication, and RNA processing proteins.

Conclusions:

• This study provides a comprehensive proteome profile of the LANA(SIM)-associated complex, detailing both SUMOylated and non-SUMOylated proteins.
• Viral-mediated gene regulation through SUMOylation by LANA is critical for KSHV persistence and Kaposi's sarcoma development.
• Findings enhance understanding of KSHV pathogenesis and LANA's multifaceted role in host-pathogen interactions.