This family of bacterial proteins includes the outer membrane lipoprotein Flpp3 from Francisella tularensis (Swiss:Q5NF33). Flpp3, a virulence determinant of tularemia, shows a six stranded beta-sheet supported with two crossing alpha-helices. It has a hydrophobic internal cavity that has been suggested to bind a small organic molecule. However, its specific function is still unknown [1, 2].

1: NMR Structure of Francisella tularensis Virulence Determinant Reveals Structural Homology to Bet v1 Allergen Proteins. Zook J, Mo G, Sisco NJ, Craciunescu FM, Hansen DT, Baravati B, Cherry BR, Sykes K, Wachter R, Van Horn WD, Fromme P; Structure. 2015;23:1116-1122. PMID:26004443

2: XFEL and NMR Structures of Francisella Lipoprotein Reveal Conformational Space of Drug Target against Tularemia. Zook J, Shekhar M, Hansen D, Conrad C, Grant T, Gupta C, White T, Barty A, Basu S, Zhao Y, Zatsepin N, Ishchenko A, Batyuk A, Gati C, Li C, Galli L, Coe J, Hunter M, Liang M, Weierstall U, Nelson G, James D, Stauch B, Craciunescu F, Thifault D, Liu W, Cherezov V, Singharoy A, Fromme P; Structure. 2020;28:540-547. PMID:32142641