An affinity switch controls hierarchical Type III protein targeting and secretion
Ontology highlight
ABSTRACT:
INSTRUMENT(S): Q Exactive
ORGANISM(S): Escherichia Coli
SUBMITTER: 
Konstantinos Tsolis
LAB HEAD: Tassos Economou
PROVIDER: PXD007087 | Pride | 2017-11-03
REPOSITORIES: Pride
Dataset's files
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Publications
Hierarchical protein targeting and secretion is controlled by an affinity switch in the type III secretion system of enteropathogenic <i>Escherichia coli</i>.
Portaliou Athina G AG Tsolis Konstantinos C KC Loos Maria S MS Balabanidou Vassileia V Rayo Josep J Tsirigotaki Alexandra A Crepin Valerie F VF Frankel Gad G Kalodimos Charalampos G CG Karamanou Spyridoula S Economou Anastassios A
The EMBO journal 20171106 23
Type III secretion (T3S), a protein export pathway common to Gram-negative pathogens, comprises a trans-envelope syringe, the injectisome, with a cytoplasm-facing translocase channel. Exported substrates are chaperone-delivered to the translocase, EscV in enteropathogenic <i>Escherichia coli,</i> and cross it in strict hierarchical manner, for example, first "translocators", then "effectors". We dissected T3S substrate targeting and hierarchical switching by reconstituting them <i>in vitro</i> u ...[more]
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Project description:Type III secretion (T3S), a protein export pathway common to Gram-negative pathogens, comprises a trans-envelope syringe, the injectisome, with a cytoplasm-facing translocase channel. Exported substrates are chaperone-delivered to the translocase, EscV in enteropathogenic Escherichia coli, and cross it in strict hierarchical manner, for example, first "translocators", then "effectors". We dissected T3S substrate targeting and hierarchical switching by reconstituting them in vitro using inverted inner membrane vesicles. EscV recruits and conformationally activates the tightly membrane-associated pseudo-effector SepL and its chaperone SepD. This renders SepL a high-affinity receptor for translocator/chaperone pairs, recognizing specific chaperone signals. In a second, SepD-coupled step, translocators docked on SepL become secreted. During translocator secretion, SepL/SepD suppress effector/chaperone binding to EscV and prevent premature effector secretion. Disengagement of the SepL/SepD switch directs EscV to dedicated effector export. These findings advance molecular understanding of T3S and reveal a novel mechanism for hierarchical trafficking regulation in protein secretion channels.
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