RVB-1 and RVB-2 are stress responsive proteins in Neurospora crassa and RVB-1 interacts with the centromeric...

The Neurospora crassa RVB-1 and RVB-2 proteins belong to the AAA+ (ATPases Associated with various cellular Activities) superfamily and are organized in a hetero-hexameric complex essential for multiple cellular processes. Although they have been described as associated with cancer, new molecular functions have recently been described for them. Here, we investigate their participation in the fungus stress response, and our results support that they are components of the regulatory mechanism involved in the cellular stress response. Results of gene and protein expression, as well as cellular localization, revealed that their expression and location are modulated under stressing conditions, such as temperature, salt, and light. Furthermore, they are components of cytoplasmic granules induced by stress. Through immunoprecipitation assays followed by mass spectrometry, we identified many RVB-1 interactors, including components of chromatin remodeling complexes, some of which showed to be involved in stress response. New RVB-1 partners were identified, such as proteins participating in carbohydrate and cell wall metabolism, cell signaling, among other processes. One such new partner is shugoshin (SGO-1), a pericentromeric protein described as a regulator of chromosomal segregation during meiosis. Using genetic and biochemical approaches, we demonstrate the RVB-1 and SGO-1 interaction, and the structural aspects were analyzed by AlphaFold3. This interaction reveals a new RVB-1 function as a protein likely important for the maintenance of the centromeric region. Our findings confirm the relevant function of RVBs as stress sensors in N. crassa and reveal new interactors, highlighting their importance in the context of cellular metabolism.