Biology subjects

Montaner, B.

Publications and source records attributed to Montaner, B..

4 recordsLinked to original sources

bioRxiv2025

SARS-CoV-2 envelope protein induces LC3 lipidation via the V-ATPase-ATG16L1 axis

Coronaviruses encode envelope (E), a structural component of the virion that is important for assembly and egress. E has proton channel activity that prevents premature rearrangement of the spike glycoprotein as virions encounter acidic compartments as they exit the cell. How infected cells respond to this pH disruption during coronavirus infection is unknown. Here we show that SARS-CoV-2 E ion channel activity triggers the proton pump V-ATPases to recruit the ATG16L1 complex during infection. This results in ATG8 molecules such as LC3B decorating perturbed compartments. This recruitment of autophagy machinery does not inhibit viral replication, rather SARS-CoV-2 exploits this response. Inhibition of the V-ATPase/ATG16L1 interaction using the Salmonella effector SopF inhibits SARS-CoV-2 replication. Careful distinction between use of the autophagic machinery from canonical macroautophagy is required in order to better understand coronavirus replication and for rational targeting of any potential host-directed therapies.

cell biology↗

bioRxiv2024

Caspase cleavage of Influenza A virus M2 disrupts M2-LC3 interaction and regulates virion production

Influenza A virus (IAV) Matrix 2 (M2) protein is an ion channel, required for efficient viral entry and egress. M2 interacts with the small ubiquitin-like LC3 protein through a cytoplasmic C-terminal LC3 interacting region (LIR). Here, we report that M2 is cleaved by caspases, abolishing the M2-LC3 interaction. A crystal structure of the M2 LIR in complex with LC3 indicates the caspase cleavage tetrapeptide motif (82SAVD85) is an unstructured linear motif that does not overlap with the LIR. Furthermore, an IAV mutant expressing a permanently truncated M2, mimicking caspase cleavage, is impaired in M2 plasma membrane transport and produces a significantly attenuated virus. Our results reveal a dynamic regulation of the M2-LC3 interaction by caspases. This highlights the role of host proteases in regulating IAV exit, relating virion production with host cell state.

microbiology↗

bioRxiv2023

The V-ATPase/ATG16L1 axis is controlled by the V1H subunit

Defects in organellar acidification indicate compromised or infected compartments. Recruitment of the autophagy-related ATG16L1 complex to pathologically de-acidified compartments targets ubiquitin-like ATG8 molecules to perturbed membranes. How this process is coupled to pH gradient disruption is unclear. Here, we reveal a direct role for the V1H subunit of the V-ATPase proton pump in recruiting ATG16L1. The interaction between V1H and ATG16L1 occurs within assembled V-ATPases, but not dissociated V1 complexes. This selectivity allows recruitment to be coupled to changes in V-ATPase assembly that follow pH dissipation. Cells lacking V1H undergo canonical macroautophagy but are unable to recruit ATG16L1 in response to influenza infection or ionophore drugs. We identify a loop within V1H that mediates ATG16L1 binding, which is absent in a neuronal isoform of V1H. Thus, V1H controls ATG16L1 recruitment in response to proton gradient dissipation, suggesting that the V-ATPase acts autonomously as a cell-intrinsic damage sensor.

molecular biology↗

bioRxiv2020

Subtractive CRISPR screen identifies factors involved in non-canonical LC3 lipidation.

Although commonly associated with autophagosomes, LC3 can also be recruited to membranes in a variety of non-canonical contexts. These include responses to ionophores such as the M2 proton channel of influenza A virus. LC3 is attached to membranes by covalent lipidation that depends on recruitment of the ATG5-12-16L1 complex. Non-canonical LC3 lipidation requires the C-terminal WD40 domain of ATG16L1 that is dispensable for canonical autophagy. We devised a subtractive CRISPR knock-out screening strategy to investigate the requirements for non-canonical LC3-lipidation. This correctly identified the enzyme complexes directly responsible for LC3-lipidation. We additionally identified the RALGAP complex as important for M2-induced, but not ionophore drug induced LC3 lipidation. In contrast, we identified ATG4D as responsible for LC3 recycling in M2-induced and basal LC3-lipidation. Identification of a vacuolar ATPase subunit in the screen suggested a common mechanism for non-canonical LC3 recruitment. Influenza-induced and ionophore drug induced LC3-lipidation leads to association of the vacuolar ATPase and ATG16L1 and can be antagonised by Salmonella SopF. LC3 recruitment to erroneously neutral compartments may therefore represent a response to damage caused by diverse invasive pathogens.

cell biology↗