29JD

NMR Structure of the Calcium bound form of OutG, major pilin from Dickeya dadantii T2SS

Summary for 29JD

• Entry DOI: 10.2210/pdb29jd/pdb
• NMR Information: BMRB: 51296
• Descriptor: Type II secretion system core protein G, CALCIUM ION (2 entities in total)
• Functional Keywords: dickeya dadantii t2ss, major pilin, pilus, secretion, protein transport
• Biological source: Dickeya dadantii
• Total number of polymer chains: 1
• Total formula weight: 13590.91

Authors

Bardiaux, B.,Jacobsen, T.,Dazzoni, R.,Nilges, M.,Francetic, O.,Shevchik, V.,Izadi-Pruneyre, N. (deposition date: 2026-03-16, release date: 2026-09-09)

Primary citation

Lejeune, M.,Ivashchenko, S.,Dazzoni, R.,Bardiaux, B.,Sonani, R.R.,Vos, M.,Jacobsen, T.,Egelman, E.H.,Nilges, M.,Francetic, O.,Shevchik, V.E.,Izadi-Pruneyre, N.
Structural determinants of endopilus assembly, stability, and functional specificity in bacterial type II secretion.
Structure, 2026

PubMed Abstract: Gram-negative bacteria employ the type II secretion system (T2SS) to transport folded protein effectors via a periplasmic helical polymer called the endopilus, composed of one major and four minor pilin subunits. Endopili resemble type IV pili but feature a conserved calcium-binding site stabilizing their major pilins. Endopilus polymerization is coupled to substrate translocation through a dedicated outer membrane channel. We compared T2SSs from plant and human pathogens, Dickeya dadantii and Klebsiella oxytoca, respectively. Despite different ecological niches and secreted effectors, their major pilins (OutG and PulG) share >77% sequence identity. Using NMR and cryo-EM, we solved structures of calcium-bound OutG monomer, as well as OutG and PulG endopili at 3.6 Å resolution. Combining structural, mutational, and biophysical analyses with in vivo assays, we identified key determinants of secretion specificity and endopilus stability. Our findings reveal how minor sequence variations in conserved nanomachines drive functional adaptation to diverse environments.

PubMed: 42624105
DOI: 10.1016/j.str.2026.07.013

Experimental method

SOLUTION NMR