A possible D,D-carboxypeptidase, that releases amino acids sequentially from a proteins C-terminus (PubMed:7972112, PubMed:12196546). Has zinc-dependent carboxypeptidase activity on synthetic depsipeptide substrates (PubMed:7972112). May serve to decrease cross-linking of peptidoglycan, promoting the highly sinusous motility of this spirochaete (Probable). Overexpression of the whole protein in E.coli leads to aberrant cell morphology and extrusion of the cytoplasm, while overexpression of a construct with the first 62 resides of the protein fused to PhoA does have this effect, suggesting the whole protein, not the lipoprotein moiety, is toxic (PubMed:7972112). Binds penicillin (PubMed:2647634, PubMed:7972112). Penicillin binding is covalent, does not require lipidation, and is zinc-dependent (PubMed:7972112, PubMed:12196546). While this protein has beta-lactamase activity in vitro, that is probably not its role in vivo, as T.pallidum is very sensitive to penicillin antibiotics (PubMed:12196546). A pathogen-specific membrane antigen (PubMed:2642466, PubMed:1372297). Most abundant of the membrane lipoproteins, only found in pathogenic treponemes, suggesting that it is an important structural moiety in the cell envelope of virulent treponemal subspecies. A lipopeptide corresponding to the first 6 mature residues induces host (human and mouse) cytokine release by monocyte cell lines via TLR2 and CD14; nonlipidated protein does not stimulate host cells (PubMed:10426995). Stimulates host (human) dendritic cell maturation to become MHC class II-positive antigen presenting cells via TLR2, which depends on lipidation; nonlipidated protein does not stimulate maturation (PubMed:11160304). Carboxypeptidase activity is stimulated by zinc (PubMed:7972112). Penicillin-binding is stimulated by zinc (PubMed:12196546). Probably a monomer; a non-lipidated construct (residues 22-434) is monomeric in solution but crystallizes as a homodimer. The N-terminus is blocked (PubMed:2642466). Present as a doublet of low abundance 48 kDa and high abundance 47 kDa proteins (PubMed:2647634, PubMed:2668192, PubMed:1372297). The longer form is probably due to readthrough of the stop codon; the extra amino acids at the C-terminus would be X-Lys-Arg-Gly-Val-Leu-Ser-Arg-Val-Ser, a peptide antibody against this sequence detects only the 48 kDa form (PubMed:2668192). A recombinant non-lipidated form (residues 20-434) is recognized by human antisera, indicating the lipidation site is not essential for antigenicity, although the acylated lipopeptide clearly is antigenic (PubMed:1372297, PubMed:10426995). The non-lipidated form binds also penicillin (PubMed:7972112).