Transports both D- and L-serine; allows growth of strain CFT073 cells normally unable to transport D-serine on that substrate. Transport relies on the H(+) gradient and is not competed by L-threonine (PubMed:26727373). May play a role in L-cysteine detoxification (By similarity). 40-fold induced under conditions that maximally induce expression of the locus of effacement (LEE) large pathogenicity island (PAI); part of the dlsT-yhaM operon. 3-fold induced by D-serine during mid to late exponential growth. Decreased secretion of a number of substrates for the type III secretion system (TTSS) encoded in the locus of effacement (LEE) including Tir, EspA and EspD; at least EspD is also decreased intracellularly. Expression of 105 genes is altered; down-regulation of LEE PAI (including the TTSS) plus other genes as well as up-regulation of 21 genes. Decreased ability to form attachment/effacing lesions on HeLa cells; those which form attachments condense host actin less well (pedestal formation) (PubMed:26727373). Belongs to the amino acid/polyamine transporter 2 family. SdaC/TdcC subfamily.