A Mycobacterium tuberculosis secreted virulence factor Rv1435c/hsr1 disrupts host snRNP biogenesis

Area of Science:

• Molecular Biology
• Immunology
• Microbiology

Background:

• Host transcriptional adaptation is crucial for combating Mycobacterium tuberculosis (Mtb) infection.
• Mtb manipulates host RNA splicing to suppress antibacterial responses, but the underlying mechanism is unclear.

Purpose of the Study:

• To elucidate the mechanism by which Mtb alters host RNA splicing.
• To identify specific Mtb proteins involved in regulating host splicing factors.
• To evaluate the role of identified Mtb proteins in Mtb pathogenesis and as potential therapeutic targets.

Main Methods:

• High-throughput yeast-2-hybrid screening to identify Mtb-secreted proteins interacting with host splicing factors.
• Custom in-cell assays to analyze the effect of Mtb proteins on RNA splicing.
• Genetic deletion studies (Δhsr1 strain) to assess the in vivo and ex vivo virulence of Mtb.
• Immunohistochemical analysis of tissue samples from infected mice and human biopsies.

Main Results:

• A secreted Mtb protein, Rv1435c/hsr1 (host splicing regulator 1), was identified as a key player in altering host splicing.
• Rv1435c/hsr1 directly interacts with Mtb phagosomes, U5 snRNA, and SNRPF, disrupting spliceosome biogenesis and causing specific exon-skipping events.
• Deletion of Rv1435c/hsr1 (Δhsr1) attenuated Mtb virulence in macrophages and mice, reversing splicing alterations.
• hsr1-dependent SNRPF staining was observed in infected mouse tissues and human intestinal tuberculosis biopsies.

Conclusions:

• Mtb utilizes the virulence factor hsr1 to disrupt host spliceosome biogenesis, thereby evading antibacterial responses.
• hsr1-mediated disruption of RNA splicing is critical for Mtb pathogenesis.
• Host and Mtb splicing regulators represent novel therapeutic targets for tuberculosis treatment.