TTRAP is a family of small bacterial proteins largely from Clostrium difficile. From comparative and other structural studies of the PDB:2L7K, UniProtKB:Q18AW3, it has been suggested that this family is required for interacting with other proteins in order to facilitate the transfer of the transposon CTn4 between different bacterial species. PDB:2L7K comprises an alpha-helical fold of four alpha-helices leading to the production of two clefts, the larger of which displays two highly conserved residues in close proximity, Glu-8 and Lys-48. The gene concerned is part of an operon within transposon CTn4, and is expressed alongside a putative DNA primase, a DNA topoisomerase and conjugal transfer proteins [1].

1: Solution NMR structure of CD1104B from pathogenic Clostridium difficile reveals a distinct alpha-helical architecture and provides first structural representative of protein domain family PF14203. Pulavarti SV, Eletsky A, Lee HW, Acton TB, Xiao R, Everett JK, Prestegard JH, Montelione GT, Szyperski T; J Struct Funct Genomics. 2013;14:155-160. PMID:24048810