ELISA analysis of FaeG interactions with the truncated APN proteins. We observed the expression of five truncated APN proteins in a prokaryotic system, including APN∆1 (401–963 AA), APN∆2 (1–400 AA), APN∆3 (332–400 AA), APN∆4 (1–331 AA), and APN∆5 (332–963 AA). We analyzed the binding activity between the five purified truncated APN proteins and FaeG using indirect ELISA. pGEX-6p-1 and pet28a (+) as negative controls. We recorded the absorbance at a wavelength of 450 nm, repeated the experiments thrice. The results shown are mean ± standard deviations (*p < 0.05, **p < 0.01).