1.B.70.1.2
OmpIIIA or RopA of 340 - 166 aas and 1 N-terminal TMS.  RopA and RopB (TC# 1.B.4.2.19), which have β-barrel structures, may be involved in the control of plant-microbial symbiosis. Kosolapova et al. 2019 demonstrated that the full-length RopA and RopB proteins form amyloid fibrils in vitro. These fibrils are β-sheet-rich, bind Thioflavin T (ThT), exhibit green birefringence upon staining with Congo Red (CR), and resist treatment with ionic detergents and proteases. Heterologously expressed RopA and RopB intracellularly aggregate in yeast and assemble into amyloid fibrils at the surface of E. coli. The capsules of the R. leguminosarum cells bind CR, exhibit green birefringence, and contain fibrils of RopA and RopB in vivo (Kosolapova et al. 2019). Based on similarity, they form passive diffusion pores that allow small molecular weight hydrophilic materials to cross the outer membrane.