SLC38A9 regulates SARS-CoV-2 viral entry.

Area of Science:

• Virology and Cell Biology
• Molecular Mechanisms of Viral Entry

Background:

• SARS-CoV-2 viral entry relies on spike (S) protein cleavage into S1 and S2 subunits.
• Furin cleavage exposes a multibasic motif on S1, crucial for infection and transmission, but its precise role is unclear.

Purpose of the Study:

• To elucidate the mechanism by which the S1 multibasic motif contributes to SARS-CoV-2 infection.
• To identify host factors interacting with the S1 motif and mediating viral entry.

Main Methods:

• Investigated the interaction between the S1 multibasic motif and host cell proteins.
• Utilized cell-based assays (Calu-3, U87MG, Caco-2, A549) with pseudo-SARS-CoV-2.
• Performed SLC38A9 knockdown experiments to assess its role in viral entry and endolysosome function.

Main Results:

• The S1 multibasic motif directly interacts with SLC38A9, an arginine sensor in endolysosomes.
• SLC38A9 knockdown inhibited S1-induced endolysosome de-acidification.
• Blocking the S1-SLC38A9 interaction prevented pseudo-SARS-CoV-2 entry into multiple cell types.

Conclusions:

• Identified a novel mechanism where S1 interacts with endolysosomal SLC38A9 to disrupt endolysosome acidification.
• This S1-SLC38A9 interaction facilitates SARS-CoV-2 escape from endolysosomes, enhancing viral entry and infection.
• Targeting the S1-SLC38A9 interaction may offer a strategy to inhibit SARS-CoV-2.