Mild acidity makes bacterial adhesion proteins let go

University of Tokyo researchers studied thioester domains, or TEDs, found across bacterial adhesion proteins and used biolayer interferometry to track binding and release in real time. The TED in the SfbI adhesion protein of group A Streptococcus pyogenes forms a strong covalent bond with host fibrinogen, yet releases it rapidly under mildly acidic conditions. Biochemical and thermodynamic analysis indicates that acidification favors the reverse of the bond-forming reaction, allowing the covalent attachment to come undone. Supporting evidence from the distantly related Clostridium perfringens CpTIE protein suggests pH sensitivity may be rooted in chemistry shared across this protein family. The work appears in Science Advances. It is a molecular-mechanism finding, not an infection treatment; different TEDs may behave differently, and tissue pH, host factors and bacterial survival strategies still need validation.