LC3B conjugation machinery promotes autophagy-independent HIV-1 entry in CD4+ T lymphocytes

Abstract

HIV-1 entry into CD4+ T lymphocytes relies on the viral and cellular membranes fusion, leading to viral capsid delivery in the cytoplasm of target cells. The conjugation of ATG8/LC3B protein, process referred to as ATG8ylation and mainly studied in the context of autophagy, occurs transiently in the early stages of the HIV-1 replication cycle in CD4+ T lymphocytes. Despite numerous studies investigating the interplays of HIV-1 with autophagy machinery, the impact of ATG8ylation in the early stages of HIV-1 infection remains unknown. Here we found that HIV-1 exposure leads to the rapid enrichment of LC3B towards the target cell plasma membrane, in close proximity with the incoming viral particles. Furthermore, we demonstrated that ATG8ylation is a key event that facilitates HIV-1 fusion with target CD4+ T cells. Interestingly, this effect is independent of the canonical autophagy pathway as ATG13 silencing does not prevent HIV-1 entry. Together, our results provide an unconventional role of LC3B conjugation subverted by HIV-1 to achieve a critical early step of its replication cycle. TeaserHIV-1 induces LC3B enrichment towards its target cell entry site and uses the conjugation of this protein to favor its entry step.