Dengue virus non-structural protein 3 inhibits mitochondrial respiration by impairing complex I function

Area of Science:

• Biochemistry
• Virology
• Cell Biology

Background:

• Dengue virus (DENV) infection impacts host cell metabolism, but the specific molecular mechanisms are not fully understood.
• Mitochondrial dysfunction is implicated in DENV pathogenesis, yet the viral factors responsible remain largely unidentified.

Purpose of the Study:

• To investigate the role of DENV non-structural protein 3 (NS3) in modulating host mitochondrial respiration.
• To determine if NS3 directly affects the electron transport system (ETS) and its components.

Main Methods:

• Proteomics analysis of DENV-infected hepatocytes to identify viral proteins in mitochondria.
• Biochemical assays using isolated mitochondria and recombinant DENV NS3 constructs to assess ETS complex activities.
• High-resolution respirometry to measure mitochondrial respiratory rates.
• In silico analysis to predict NS3 interactions with mitochondrial respiratory chain subunits.

Main Results:

• DENV NS3 was identified in mitochondria of infected cells, associated with a decrease in ETS host proteins.
• Recombinant NS3 protease domain (NS3pro) impaired Complex I (CI) activity in isolated mitochondria, but not other ETS complexes.
• NS3 reduced mitochondrial respiration rates without affecting membrane potential or leak respiration, indicating targeted CI inhibition.
• In silico analysis predicted potential NS3 cleavage sites on CI subunits in both mouse and human.

Conclusions:

• DENV NS3 directly modulates mitochondrial bioenergetics by inhibiting Complex I function.
• The proteolytic activity of NS3 appears necessary for impairing CI function.
• NS3 represents a key viral factor contributing to DENV-induced metabolic alterations by targeting mitochondrial respiration.