Dynamic interplay between the periplasmic and transmembrane domains of GspL and GspM in the type II secretion system.
The type II secretion system (T2SS) is a multiprotein nanomachine that transports folded proteins across the outer membrane of gram-negative bacteria. The molecular mechanisms that govern the secretion process remain poorly understood. The inner membrane components GspC, GspL and GspM possess a single transmembrane segment (TMS) and a large periplasmic region and they are thought to form a platform of unknown function. Here, using two-hybrid and pull-down assays we performed a systematic mapping of the GspC/GspL/GspM interaction regions in the plant pathogen Dickeya dadantii. We found that the TMS of these components interact with each other, implying a complex interaction network within the inner membrane. We also showed that the periplasmic, ferredoxin-like, domains of GspL and GspM drive homo- and heterodimerizations of these proteins. Disulfide bonding analyses revealed that the respective domain interfaces include the equivalent secondary-structure elements, suggesting alternating interactions of the periplasmic domains, L/L and M/M versus L/M. Finally, we found that displacements of the periplasmic GspM domain mediate coordinated shifts or rotations of the cognate TMS. These data suggest a plausible mechanism for signal transmission between the periplasmic and the cytoplasmic portions of the T2SS machine.
INSA-Lyon, Villeurbanne, France ; CNRS, UMR5240, Microbiologie Adaptation et Pathogénie, Lyon, France.
Mathilde
M
Lallemand
Frédéric H
FH
Login
Natalia
N
Guschinskaya
Camille
C
Pineau
Géraldine
G
Effantin
Xavier
X
Robert
Vladimir E
VE
Shevchik
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D058947:Bacterial Secretion Systems; D002462:Cell Membrane / Q000378:metabolism*; D004755:Enterobacteriaceae / Q000166:cytology*; D005288:Ferredoxins / Q000737:chemistry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016296:Mutagenesis; D019897:Periplasm / Q000378:metabolism*; D011485:Protein Binding; D055503:Protein Multimerization; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary
D001426:Bacterial Proteins; D058947:Bacterial Secretion Systems; D005288:Ferredoxins