Component of the VELB-VOSA heterodimeric complex that plays a dual role in activating genes associated with spore maturation and repressing certain development-associated genes (By similarity). The complex binds DNA through the DNA-binding domain of VOSA that recognizes an 11-nucleotide consensus sequence 5'-CTGGCCGCGGC-3' consisting of two motifs in the promoters of key developmental regulatory genes (By similarity). Appears dispensable for the development and pathogenicity (PubMed:24632440). Forms a heterodimeric complex with VELB; the formation of the VELB-VOSA complex is light-dependent (By similarity). The N-terminal velvet domain contains a NF-kappa-B-like fold and is involved in DNA-binding (By similarity). Belongs to the velvet family. VosA subfamily.