Tetramer formation of Bacillus subtilis YabJ protein that belongs to YjgF/YER057c/UK114 family

Bacillus subtilis YabJ protein belongs to the highly conserved YjgF/YER057c/UK114 family, which has a homotrimeric quaternary structure. The dominant allele of yabJ gene that is caused by a single amino acid mutation of Ser103Phe enables poly-gamma-glutamic acid (gamma PGA) production of B. subtilis under conditions where the cell-density signal transduction was disturbed by the loss of DegQ function. X-ray crystallography of recombinant proteins revealed that unlike the homotrimeric wild-type YabJ, the mutant YabJ(Ser103Phe) had a homotetrameric quaternary structure, and the structural change appeared to be triggered by an inversion of the fifth beta-strand. The YabJ homotetramer has a hole that is highly accessible, penetrating through the tetramer, and 2 surface concaves as potential ligand-binding sites. Western blot analyses revealed that the conformational change was also induced in vivo by the Ser103Phe mutation.

Automated summary

The study revealed that the dominant allele of yabJ gene caused by a single amino acid mutation leads to changes in B. subtilis production, and the structural change may be related to the inversion of the fifth beta-strand, affecting its ligand-binding capability.