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The YopD translocator of Yersinia pseudotuberculosis is a multifunctional protein comprised of discrete domains.
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för molekylärbiologi (Teknisk-naturvetenskaplig fakultet). (Wolf-Watz)
Umeå universitet, Medicinska fakulteten, Institutionen för molekylärbiologi (Medicinska fakulteten). (Francis)
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för molekylärbiologi (Teknisk-naturvetenskaplig fakultet). (Forsberg)
Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för molekylärbiologi (Teknisk-naturvetenskaplig fakultet). Umeå universitet, Medicinska fakulteten, Umeå Centre for Microbial Research (UCMR). (Forsberg)
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2004 (Engelska)Ingår i: Journal of Bacteriology, ISSN 0021-9193, E-ISSN 1098-5530, Vol. 186, nr 13, s. 4110-4123Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

To establish an infection, Yersinia pseudotuberculosis utilizes a plasmid-encoded type III translocon to microinject several anti-host Yop effectors into the cytosol of target eukaryotic cells. YopD has been implicated in several key steps during Yop effector translocation, including maintenance of yop regulatory control and pore formation in the target cell membrane through which effectors traverse. These functions are mediated, in part, by an interaction with the cognate chaperone, LcrH. To gain insight into the complex molecular mechanisms of YopD function, we performed a systematic mutagenesis study to search for discrete functional domains. We highlighted amino acids beyond the first three N-terminal residues that are dispensable for YopD secretion and confirmed that an interaction between YopD and LcrH is essential for maintenance of yop regulatory control. In addition, discrete domains within YopD that are essential for both pore formation and translocation of Yop effectors were identified. Significantly, other domains were found to be important for effector microinjection but not for pore formation. Therefore, YopD is clearly essential for several discrete steps during efficient Yop effector translocation. Recognition of this modular YopD domain structure provides important insights into the function of YopD.

Ort, förlag, år, upplaga, sidor
2004. Vol. 186, nr 13, s. 4110-4123
Nyckelord [en]
Bacterial Outer Membrane Proteins/chemistry/*physiology, Bacterial Proteins/physiology, Base Sequence, Hela Cells, Hemolysis, Humans, Molecular Chaperones/physiology, Molecular Sequence Data, Protein Transport, Yersinia pseudotuberculosis/*physiology
Identifikatorer
URN: urn:nbn:se:umu:diva-16673DOI: 10.1128/JB.186.13.4110-4123.2004PubMedID: 15205412OAI: oai:DiVA.org:umu-16673DiVA, id: diva2:156346
Tillgänglig från: 2007-10-08 Skapad: 2007-10-08 Senast uppdaterad: 2018-06-09Bibliografiskt granskad
Ingår i avhandling
1. Delivery of TypeIII Secreted Toxins by Yersinia pseudotuberculosis: the Role of LcrV, YopD, and Free Lipids in the Translocation Process
Öppna denna publikation i ny flik eller fönster >>Delivery of TypeIII Secreted Toxins by Yersinia pseudotuberculosis: the Role of LcrV, YopD, and Free Lipids in the Translocation Process
2006 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

Bacteria that infect humans and animals face a hard combat with the host´s immune system and in order to establish infection, pathogenic bacteria has evolved mechanisms to avoid being cleared from the host tissue. Many Gram-negatives carry a Type 3 secretion (T3S) system that is used to deliver effector proteins (toxins) into host cells. The toxins exhibit a broad range of intra cellular effects that has in common that they increase the chances of the bacteria to establish infection, multiply in infected tissue or spread to other tissues or hosts. The object of this study was to analyse the mechanisms behind the T3S effectors delivery into target cells. Two bacterial proteins, LcrV and YopD, which are involved in the translocation of effectors were analyzed by mutagenesis. LcrV was found to affect the efficiency of the translocation, probably by determining the size of the pore in the target cell membrane through which the effectors pass. Truncated variants of the multi-functional YopD revealed that defined regions of the protein were important for pore-formation and translocation. Effectors and translocators were demonstrated to form complexes with free acyl chains (lipids) at the bacterial surface. These complexes –termed Yop-lipid complexes, (YLC)– are released from the surface and can act as discrete units that are able to promote translocation of effectors even when separated from the bacterium from which they originate. These findings shed new light on the process of effector translocation by Yersinia and possibly by other gram-negative bacterial pathogens with a similar T3S setup.

Ort, förlag, år, upplaga, sidor
Umeå: Molekylärbiologi (Teknisk-naturvetenskaplig fakultet), 2006. s. 60
Nyckelord
Yersinia, T3SS, translocation, YopD, LcrV, YLC, fatty acids.
Nationell ämneskategori
Biokemi och molekylärbiologi
Identifikatorer
urn:nbn:se:umu:diva-800 (URN)91-7264-092-8 (ISBN)
Disputation
2006-06-02, major groove, 6L, NUS, 901 87, Umeå, 10:00 (Engelska)
Opponent
Handledare
Tillgänglig från: 2006-05-11 Skapad: 2006-05-11 Senast uppdaterad: 2019-01-21Bibliografiskt granskad
2. Multiple twists in the molecular tales of YopD and LcrH in type III secretion by Yersinia pseudotuberculosis
Öppna denna publikation i ny flik eller fönster >>Multiple twists in the molecular tales of YopD and LcrH in type III secretion by Yersinia pseudotuberculosis
2007 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

The type III secretion system (T3SS) is a highly conserved secretion system among Gram negative bacteria that translocates anti-host proteins directly into the infected cells to overcome the host immune system and establish a bacterial infection. Yersinia pseudotuberculosis is one of three pathogenic Yersinia spp. that use a plasmid encoded T3SS to establish an infection. This complex multi-component Ysc-Yop system is tightly regulated in time and space. The T3SS is induced upon target cell contact and by growth in the absence of calcium. There are two kinds of substrates for the secretion apparatus, the translocator proteins that make up the pore in the eukaryotic target cell membrane, and the translocated effector proteins, that presumably pass through this pore en route to the eukaryotic cell interior.

The essential YopD translocator protein is involved in several important steps during effector translocation, such as pore formation, effector translocation. Moreover, in complex with its cognate chaperone LcrH, it maintains regulatory control of yop gene expression. To understand the molecular mechanism of YopD function, we made sequential in-frame deletions throughout the entire protein and identified discrete functional domains that made it possible to separate the role of YopD in translocation from its role in pore formation and regulation, really supporting translocation to be a multi-step process. Further site-directed mutagenesis of the YopD C-terminus, a region important for these functions, revealed no function for amino acids in the coiled-coil domain, while hydrophobic residues within the alpha-helical amphipathic domain are functionally significant for regulation, pore formation and translocation of effectors.

Unique to the T3SSs are the chaperones which are required for efficient type III protein secretion. The translocator-class chaperone LcrH binds two translocator proteins, YopB and YopD, which is necessary for their pre-secretory stabilization and their efficient secretion. We have shown that LcrH interacts with each translocator at a unique binding-site established by the folding of its three tandem tetratricopeptide repeats (TPRs). Beside the regulatory LcrH-YopD complex, LcrH complexes with YscY, a component of the Ysc-Yop T3SS, that is also essential for regulatory control. Interestingly the roles for LcrH do not end here, because it also appears to function in fine tuning the amount of effector translocation into target cells upon cell contact. Moreover, LcrH’s role in pre-secretory stability appears to be an in vitro phenomenon, since upon bacteria-host cell contact we found accumulated levels of YopB and YopD inside the bacteria in absence of a LcrH chaperone. This suggests the true function of LcrH is seen during target cell contact. In addition, these stable YopB and YopD are secreted in a Ysc-Yop independent manner in absence of a functional LcrH. We propose a role for LcrH in conferring substrate secretion pathway specificity, guiding its substrate to the cognate Ysc-Yop T3SS to secure subsequent effector translocation.

Together, this work has sought to better understand the key functions of LcrH and YopD in Yersinia pathogenicity. Using an approach based heavily on recombinant DNA technology and tissue culture infections, the complex molecular cross-talk between chaperone and its substrate, and the effect this has on the Yersinia lifestyle, are now being discovered.

Ort, förlag, år, upplaga, sidor
Umeå: Molekylärbiologi (Teknat- och Medfak), 2007. s. 88
Serie
Umeå University medical dissertations, ISSN 0346-6612 ; 1074
Nyckelord
Yersinia pseudotuberculosis, T3SS, YopD, translocation process, LcrH, class II chaperone, substrate secretion pathway specificity
Nationell ämneskategori
Biokemi och molekylärbiologi
Identifikatorer
urn:nbn:se:umu:diva-985 (URN)91-7264-231-9 (ISBN)
Disputation
2007-02-16, Major Groove, 6 L NUS, Umeå Universitet, Umeå, 09:00 (Engelska)
Opponent
Handledare
Tillgänglig från: 2007-01-31 Skapad: 2007-01-31 Senast uppdaterad: 2019-01-23Bibliografiskt granskad

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