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.
This family belongs to the APC Superfamily.
References:
Lehman, M.K., N.A. Sturd, F. Razvi, D.L. Wellems, S.D. Carson, and P.D. Fey. (2023). Proline transporters ProT and PutP are required for Staphylococcus aureus infection. PLoS Pathog 19: e1011098.
Vastermark, A., S. Wollwage, M.E. Houle, R. Rio, and M.H. Saier, Jr. (2014). Expansion of the APC superfamily of secondary carriers. Proteins 82: 2797-2811.
Examples:
TC#	Name	Organismal Type	Example
2.A.120.1.1	Putative permease of 349 aas	Firmicutes	PP of Staphylococcus epidermidis

2.A.120.1.10	Putative amino acid transporter, YkvI	Firmicutes	YkvI of Bacillus subtilis

2.A.120.1.11	Putative amino acid uptake porter of 700 aas, BrkK, with a C-terminal Lactamase B domain.	Firmicutes	BrkK of Eubacterium brachy

2.A.120.1.12	Putative alanine:sodium symporter	Firmicutes	*Putative transporter of Mogibacterium* sp.**

2.A.120.1.13	Uncharacterized protein	Crenarchaota	UP of Caldivirga maquilingensis

2.A.120.1.14	Proline transporter, ProT, of 355 aas and 10 TMSs in a 2 + 3 + 2 + 3 TMS arrangement. It is a major proline uptake transporter in S. aureus and is required for infection in skin and soft tissues. In minimal medium it is the major proline uptake porter (Lehman et al. 2023). Its ortholog in S. carnosis (TC# 2.A.120.1.8) is 71% identical to this protein.		ProT of Staphylococcus aureus

2.A.120.1.2	Putative permease of 372 aas	Firmicutes	PP of Coprococcus catus

2.A.120.1.3	Putative permease of 496 aas	Firmicutes	PP of Clostridium botulinum

2.A.120.1.4	Putative permease of 378 aas	Prtoteobacteria	PP of Sphingopyxis alaskensis

2.A.120.1.5	Putative permease of 378 aas	Archaea	PP of Pyrococcus horikoshii

2.A.120.1.6	Putative permease of 326 aas	Firmicutes	PP of Caldicellulosiruptor kristjanssonii

2.A.120.1.7	Putative permease of 358 aas	Firmicutes	PP of Desulfotomaculum acetoxidans

2.A.120.1.8	Putative permease of 355 aas, ProT. It is 71% identical to the S. aureus ortholog, ProT (TC# 2.A.120.1.14), which has been shown to be the major proliine uptake transporter in S. aureus and is essential for infections in skin and soft tissues when external proline is provided as a source of this amino acid in minimal growth media (Lehman et al. 2023).	Firmicutes	ProT of Staphylococcus carnosus

2.A.120.1.9	Putative amino acid transporter, YyaD, which possibly plays a role in sporulation.	Firmicutes	YyaD of Bacillus subtilis

Examples:
TC#	Name	Organismal Type	Example