Two substrate-targeting sites in the Yersinia protein tyrosine phosphatase co-operate to promote bacterial virulence

YopH is a protein tyrosine phosphatase and an essential virulence determinant of the pathogenic bacterium Yersinia. Yersinia delivers YopH into infected host cells using a type III secretion mechanism. YopH dephosphorylates several focal adhesion proteins including p130Cas in human epithelial cells, resulting in disruption of focal adhesions and cell detachment from the extracellular matrix. How the C-terminal protein tyrosine phosphatase domain of YopH targets specific substrates such as p130Cas in the complex milieu of the host cell has not been fully elucidated. An N-terminal non-catalytic domain of YopH binds p130Cas in a phosphotyrosine-dependent manner and functions as a novel substrate-targeting site. The structure of the YopH protein tyrosine phosphatase domain bound to a model phosphopeptide substrate was solved and the resulting structure revealed a second substrate-targeting site (‘site 2’) within the catalytic domain. Site 2 binds to p130Cas in a phosphotyrosine-dependent manner, and co-operates with the N-terminal domain (‘site 1’) to promote efficient recognition of p130Cas by YopH in epithelial cells. The identification of two substrate-targeting sites in YopH that co-operate to promote epithelial cell detachment and bacterial virulence reinforces the importance of protein–protein interactions for determining protein tyrosine phosphatase specificity in vivo , and highlights the sophisticated nature of microbial pathogenicity factors.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73103/1/j.1365-2958.2005.04477.x.pd

Vaccination of Mice with a Yop Translocon Complex Elicits Antibodies That Are Protective against Infection with F1− Yersinia pestis▿

Yersinia pestis, the bacterial agent of plague, secretes several proteins important for pathogenesis or host protection. The F1 protein forms a capsule on the bacterial cell surface and is a well-characterized protective antigen but is not essential for virulence. A type III secretion system that is essential for virulence exports Yop proteins, which function as antiphagocytic or anti-inflammatory factors. Yop effectors (e.g., YopE) are delivered across the host cell plasma membrane by a translocon, composed of YopB and YopD. Complexes of YopB, YopD, and YopE (BDE) secreted by Yersinia pseudotuberculosis were purified by affinity chromatography and used as immunogens to determine if antibodies to the translocon could provide protection against Y. pestis in mice. Mice vaccinated with BDE generated high-titer immunoglobulin G antibodies specific for BDE, as shown by enzyme-linked immunosorbent assay and immunoblotting, and were protected against lethal intravenous challenge with F1− but not F1+ Y. pestis. Mice passively immunized with anti-BDE serum were protected from lethal challenge with F1− Y. pestis. The YopB protein or a complex of YopB and YopD (BD) was purified and determined by vaccination to be immunogenic in mice. Mice actively vaccinated with BD or passively vaccinated with anti-BD serum were protected against lethal challenge with F1− Y. pestis. These results indicate that anti-translocon antibodies can be used as immunotherapy to treat infections by F1− Y. pestis

Clinical Features and Management of the Disease Caused by New Coronaviral Infection (COVID-19) in Children. Version 2

The Ministry of Health of the Russian Federation jointly with professional association and experts in the field of pediatrics, infectious diseases and resuscitation has revised guidelines “Clinical Features and Management of the Disease Caused by New Coronaviral Infection (COVID-19) in Children” in order to provide the child population with effective medical care during the pandemic of the new coronaviral infection. The practical experience of specialists from various countries was considered during the development of this document. Special attention should be given to the evidence base of the presented data, as well as to the efficiency and safety issues of medications used in treatment of coronaviral infection and its complications. The authors highlight the problems of prevention, diagnostics and management of pathological conditions caused by COVID-19 in the article according to the presented guidelines. Patient’s management is presented depending on the age and severity of the disease itself. The therapy is considered with regard to etiological, pathogenetic and symptom focus