Physiology and substrate specificity of two closely related amino acid transporters, SerP1 and SerP2, of Lactococcus lactis.

ABSTRACT: The serP1 and serP2 genes found adjacently on the chromosome of Lactococcus lactis strains encode two members of the amino acid-polyamine-organocation (APC) superfamily of secondary transporters that share 61% sequence identity. SerP1 transports L-serine, L-threonine, and L-cysteine with high affinity. Affinity constants (Km) are in the 20 to 40 μM range. SerP2 is a DL-alanine/DL-serine/glycine transporter. The preferred substrate appears to be DL-alanine for which the affinities were found to be 38 and 20 μM for the D and L isomers, respectively. The common substrate L-serine is a high-affinity substrate of SerP1 and a low-affinity substrate of SerP2 with affinity constants of 18 and 356 μM, respectively. Growth experiments demonstrate that SerP1 is the main L-serine transporter responsib

SUBMITTER: Noens EE 

PROVIDER: S-EPMC4325105 | biostudies-literature | 2015 Mar

REPOSITORIES: biostudies-literature