Vanillate is converted to protocatechuate by the action of vanillate demethylase encoded by vanAB. Convergent upon and overlapping Acinetobacter vanB is an open reading frame encoding a member of the gntR repressor family and designated vanR. This gene organization differs from that found in a Pseudomonas isolate. An Acinetobacter strain with a knockout mutation in vanR constitutively converted vanillate to protocatechuate. Reverse transcriptase-polymerase chain reaction was used to demonstrate that control of vanAB was exerted at the level of transcription.