2.A.120 The Proline/Amino Acid Permease (PAAP) Family
The PAAP family consists of many proteins all of a uniform topology with a 5 + 5 TMS repeat in a 2 + 3 + 2 + 3 arrangement. These proteins show similarity to members of the LIVCS family (TC# 2.A.26) in the APC Superfamily (Vastermark et al. 2014). One member of this family has been functionally characterized, and it is listed with TC# 2.A.120.1.14 (Lehman et al. 2023). It is a proline uptake porter that is one of two proline uptake porters required for proline uptake in minimal media, and it is required for the establishment of S. aureus infections in skin and soft tissues (Lehman et al. 2023). A large majority of the genes encoding these transporters occur in operons or gene clusters encoding enzymes of amino acid metabolism. These incude proteases, sporulation proteins, amino acid aminotransferases, amino acid and oxo acid oxidoreductases, and amino acid tRNA synthetases.