Answer
${H_2C_6H_7O_5}^-(aq) + H_2O(l) -> H_3C_6H_7O_5(aq) + OH^-(aq) $
Work Step by Step
If ${H_2C_6H_7O_5}^-(aq)$ is going to act like a base, it will receive a $H^+$ from water:
${H_2C_6H_7O_5}^-(aq) + H_2O(l) -> H_3C_6H_7O_5(aq) + OH^-(aq) $