Involved in uptake and accumulation of various osmoprotectants. Allows the uptake of glycine betaine, proline, ectoine, and pipecolic acid (PubMed:8550465, PubMed:16000740). May be a contributory factor in the infection progression within the host (PubMed:15720084). Induced by osmotic strength and repressed by osmoprotectants. Expression is not affected by the growth phase. Disruption of the gene enhances aggressiveness of the bacterium. Under anaerobic conditions, disruption increases pectate lyase (Pel) production and increases the maceration efficiency on potato tubers (PubMed:15720084). Uptake of glycine betaine and choline is completely abolished in the ousA-ousB double mutant (PubMed:16000740). Belongs to the major facilitator superfamily. Sugar transporter (TC 2.A.1.1) family.