Positive regulator of sigma-B activity. Non-phosphorylated RsbV binds to RsbW, preventing its association with sigma-B. When phosphorylated, releases RsbW, which is then free to complex with and inactivate sigma-B. Monomer (Probable). In stressed cells, forms a complex with RsbW. The predominant form of this complex has a stoichiometry of 2:2 (one dimer of RsbW is bound by two monomers of RsbV). Binds to RsbW in the presence of low levels of ATP or under conditions of energy or environmental stress (through dephosphorylation by RsbP or RsbU). Phosphorylated by RsbW on a serine residue. Dephosphorylated by RsbP or RsbU. Belongs to the anti-sigma-factor antagonist family.