title: Rejection of impassable substrates by Yersinia type III secretion machines.
abstract: Type III machines of pathogenic Yersinia spp. transport Yop proteins across the bacterial envelope into host cells. Translational fusions of yopE to the dihydrofolate reductase gene (dhfr) or the beta-galactosidase gene (lacZ) generate hybrid proteins that block type III injection of Yop proteins into host cells, consistent with the canonical view that impassable DHFR and LacZ hybrids jam secretion machines. Mutations in repressors of posttranscriptional gene regulation, Yersinia enterocolitica yscM1 and yscM2 as well as Yersinia pestis lcrQ, relieve the YopE-DHFR-imposed blockade and restore type III injection into host cells. Genetic suppression of the type III blockade does not, however, promote YopE-DHFR secretion. A model is proposed whereby rejection of YopE-DHFR from the secretion pathway inhibits type III gene expression.
authors.affiliation: Department of Microbiology, University of Chicago, Illinois 60637, USA.
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Sorg
authors.forename: Nathan C
authors.initials: NC
authors.lastname: Miller
authors.forename: Melanie M
authors.initials: MM
authors.lastname: Marketon
authors.forename: Olaf
authors.initials: O
authors.lastname: Schneewind
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D012634:Bodily Secretions / Q000502:physiology; D015964:Gene Expression Regulation, Bacterial; D006367:HeLa Cells; D006801:Humans; D007763:Lac Operon; D011993:Recombinant Fusion Proteins / Q000235:genetics* / Q000378:metabolism; D013379:Substrate Specificity; D013762:Tetrahydrofolate Dehydrogenase / Q000235:genetics / Q000378:metabolism; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism; D014774:Virulence; D015009:Yersinia Infections / Q000382:microbiology*; D015008:Yersinia enterocolitica / Q000235:genetics* / Q000378:metabolism* / Q000472:pathogenicity; D015010:Yersinia pestis / Q000235:genetics* / Q000378:metabolism* / Q000472:pathogenicity; D001616:beta-Galactosidase / Q000235:genetics / Q000378:metabolism
chemical_list: D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D011993:Recombinant Fusion Proteins; C081269:SycE protein, Yersinia; D015534:Trans-Activators; C063239:yopE protein, Yersinia; D013762:Tetrahydrofolate Dehydrogenase; D001616:beta-Galactosidase