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Autoproteolysis of YscU of Yersinia pseudotuberculosis is important for regulation of expression and secretion of Yop proteins
Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology). (Wolf-Watz)
Umeå University, Faculty of Medicine, Department of Clinical Microbiology, Infectious Diseases.
Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Medicine, Department of Molecular Biology (Faculty of Medicine).
Umeå University, Faculty of Medicine, Molecular Infection Medicine Sweden (MIMS). Umeå University, Faculty of Science and Technology, Department of Molecular Biology (Faculty of Science and Technology). Umeå University, Faculty of Medicine, Umeå Centre for Microbial Research (UCMR). (Wolf-Watz)
2009 (English)In: Journal of Bacteriology, ISSN 0021-9193, E-ISSN 1098-5530, Vol. 191, no 13, 4259-4267 p.Article in journal (Refereed) Published
Abstract [en]

YscU of Yersinia can be autoproteolysed to generate a 10-kDa C-terminal polypeptide designated YscU(CC). Autoproteolysis occurs at the conserved N downward arrowPTH motif of YscU. The specific in-cis-generated point mutants N263A and P264A were found to be defective in proteolysis. Both mutants expressed and secreted Yop proteins (Yops) in calcium-containing medium (+Ca(2+) conditions) and calcium-depleted medium (-Ca(2+) conditions). The level of Yop and LcrV secretion by the N263A mutant was about 20% that of the wild-type strain, but there was no significant difference in the ratio of the different secreted Yops, including LcrV. The N263A mutant secreted LcrQ regardless of the calcium concentration in the medium, corroborating the observation that Yops were expressed and secreted in Ca(2+)-containing medium by the mutant. YscF, the type III secretion system (T3SS) needle protein, was secreted at elevated levels by the mutant compared to the wild type when bacteria were grown under +Ca(2+) conditions. YscF secretion was induced in the mutant, as well as in the wild type, when the bacteria were incubated under -Ca(2+) conditions, although the mutant secreted smaller amounts of YscF. The N263A mutant was cytotoxic for HeLa cells, demonstrating that the T3SS-mediated delivery of effectors was functional. We suggest that YscU blocks Yop release and that autoproteolysis is required to relieve this block.

Place, publisher, year, edition, pages
2009. Vol. 191, no 13, 4259-4267 p.
National Category
Medical and Health Sciences
Research subject
Medicine
Identifiers
URN: urn:nbn:se:umu:diva-32213DOI: 10.1128/JB.01730-08PubMedID: 19395493OAI: oai:DiVA.org:umu-32213DiVA: diva2:301977
Available from: 2010-03-03 Created: 2010-03-03 Last updated: 2017-12-12Bibliographically approved
In thesis
1. Meticulous control of the T3SS of Yersinia is essential for full virulence
Open this publication in new window or tab >>Meticulous control of the T3SS of Yersinia is essential for full virulence
2011 (English)Doctoral thesis, comprehensive summary (Other academic)
Alternative title[sv]
Minutiös kontroll av Yersinias T3SS är essentiellt för fullständig virulens
Abstract [en]

The type III secretion system (T3SS) of pathogenic Yersinia pseudotuberculosis is involved in virulence. The syringe-like secretion system spans both bacterial membranes and is responsible for the ability of Yersinia to transfer toxic proteins (Yop proteins) into the eukaryotic target cell. The T3SS is believed to have evolved from the flagellum and regulation of the T3SS is a complex event that involves a series of regulatory proteins, whereby two are YscP and YscU. In a regulatory model, called the substrate specificity switch, both proteins act together to ensure proper T3SS structure and function by regulating a stop in YscF needle protein export with a shift to Yop effector secretion. YscU undergoes autoproteolysis at a conserved motif consisting of amino acids Asparagine-Proline-Threonine-Histidine (NPTH). Processing generates a C-terminal 10 kDa peptide, YscUCC. Processing is crucial for proper T3SS regulation and function both in vitro and in vivo. Full-length YscU does not support Yop secretion and after cleavage, YscUCC remains attached to the rest of YscU and acts as a negative block on T3S. Relief of this negative block is suggested to occur through displacement of YscUCC from the rest of YscU. Thorough control of many different cellular processes is brought by the heat shock proteins (HSPs) DnaK and DnaJ. Due to their multiple regulatory functions, mutations in the hsp-genes lead to pleiotropic effects. DnaK and DnaJ are essential for proper flagellum driven motion of bacteria, but more so; they ensure proper Yersinia T3SS function in vivo. Furthermore, DnaJ interacts with YscU and may be directly involved in T3SS regulation. Virulence of Yersinia is regulated on many levels. A previously identified virulence associated protein, VagH, is now characterized as an S-adenosyl-methionine dependent methyltransferase. The targets of the methylation activity of VagH are release factors 1 and 2 (RF1 and RF2), that are important for translation termination. The enzymatic activity of VagH is important for Yop secretion and a vagH mutant up-regulates a T3SS negative regulatory protein, YopD. Furthermore, a vagH mutant is avirulent in a mouse infection model, but is not affected in macrophage intracellular survival. The importance of VagH in vivo makes it a possible target for novel antimicrobial therapy.

Place, publisher, year, edition, pages
Umeå: Institutionen för molekylärbiologi, Teknisk-naturvetenskaplig fakultet, Umeå universitet, 2011. 76 p.
Keyword
Yersinia, type III secretion, YscU, substrate specificity switch, heat shock proteins, VagH, methyltransferase, virulence
National Category
Biochemistry and Molecular Biology
Research subject
Molecular Biology
Identifiers
urn:nbn:se:umu:diva-42577 (URN)978-91-7459-168-2 (ISBN)
Public defence
2011-05-13, Naturvetarhuset, N320, Umeå universitet, Umeå, 10:00 (English)
Opponent
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Available from: 2011-04-19 Created: 2011-04-11 Last updated: 2011-04-19Bibliographically approved

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Björnfot, Ann-CatrinLavander, MoaForsberg, ÅkeWolf-Watz, Hans
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Molecular Infection Medicine Sweden (MIMS)Department of Molecular Biology (Faculty of Science and Technology)Infectious DiseasesDepartment of Molecular Biology (Faculty of Medicine)Umeå Centre for Microbial Research (UCMR)
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