- ASU Hosts Nozzle Maker Workshop
- XFEL Science Highlighted in Nature
- BioXFEL researchers capture the highest-resolution protein snapshots ever taken with an X-ray laser, revealing new details in a well-studied protein that acts as an “eye” in bacteria.
- Science Director Dr. John Spence named Royal Society Fellow
- BioXFEL Graduate Student Joey Olmos (Rice) Earns NSF Graduate Research Fellowship
- Tuesday, 14 March 2017 02:55
BinAB is a naturally occurring paracrystalline larvicide distributed worldwide to combat the devastating diseases borne by mosquitoes. These crystals are composed of homologous molecules, BinA and BinB, which play distinct roles in the multi-step intoxication process, transforming from harmless, robust crystals, to soluble protoxin heterodimers, to internalized mature toxin, and finally to toxic oligomeric pores.
The small size of the crystals—50 unit cells per edge, on average—has impeded structural characterization by conventional means. Here we report the structure of Lysinibacillus sphaericus BinAB solved de novo by serial-femtosecond crystallography at an X-ray free-electron laser. The structure reveals tyrosine- and carboxylate-mediated contacts acting as pH switches to release soluble protoxin in the alkaline larval midgut. An enormous heterodimeric interface appears to be responsible for anchoring BinA to receptor-bound BinB for co-internalization. Remarkably, this interface is largely composed of propeptides, suggesting that proteolytic maturation would trigger dissociation of the heterodimer and progression to pore formation.