A novel mechanism for utilization of extracellular AMP in Vibrio parahaemolyticus

Vibrio parahaemolyticus could grow with AMP, ADP or ATP as the sole source of carbon. In the presence of Cl-, a membrane-bound Cl(-)-dependent 5'-nucleotidase seemed to hydrolyze the nucleotides extracellularly, and then the cells took up the resulting adenosine. In the absence of Cl-, although no significant dephosphorylation of the nucleotides occurred, the cells could still grow with AMP, but not with ADP or ATP. Moreover, in the presence of Cl-, Zn2+ inhibited the 5'-nucleotidase, and inhibited growth of the cells with ADP or ATP, but not with AMP, as the carbon source. V. parahaemolyticus was unable to grow with adenine or ribose 5-phosphate. These results suggested that the cells might have an AMP transport system. In fact, Na+ uptake was observed on addition of AMP to a cell suspension in the absence of Cl-, indicating Na+-AMP cotransport.