1,720,974 research outputs found
Le proteine micobatteriche PE: localizzazione cellulare e possibile utilizzo per lo sviluppo di un sistema di antigen display
No full textMycobacterium tuberculosis (Mtb) is the causative agent of tuberculosis, a chronic infectious disease that is responsible for the death of over two million people each year.
The genome of Mtb strain H37Rv is made up of 4,411,529 nucleotides and encodes about 3986 proteins. One of the major surprise risen from the genome sequence, published in 1998, is the presence of two large unrelated families of proteins with unknown functions. These protein families are referred to as PE/PPE family of genes.
The PE family of Mycobacterium tuberculosis includes 98 proteins which share a highly homologous N-terminus sequence of about 110 amino acids (PE domain). Depending on the C-terminal domain, the PE family can be divided in three subfamilies, the largest of which is the PE_PGRS with 61 members.
In this study, we determined the cellular localization of three PE proteins by cell fractionation and immunoelectron microscopy by expressing chimeric epitope-tagged recombinant proteins in Mycobacterium smegmatis. We demonstrate that the PE domains of PE_PGRS33 and PE11 (a protein constituted by the only PE domain) contain the information necessary for cell wall localization, and that they can be used as fusion partners to deliver a sufficiently long C-terminus-linked protein domain on the mycobacterial cell surface. Indeed, we demonstrate that PE_PGRS33 and Rv3097c (a lipase belonging to the PE family) are surface exposed and localize in the mycobacterial cell wall. Moreover, we found that PE_PGRS33 is easily extractable by detergents suggesting its localization in the mycobacterial outer membrane. Beyond defining the cellular localization of these proteins, and a function for their PE domains, these data open the interesting possibility to construct recombinant mycobacteria expressing heterologous antigens on their surface for vaccine purposes
Targeting type VII/ESX secretion systems for development of novel antimycobacterial drugs
No full textThe emergence of multi- and extensively-drug resistant strains of Mycobacterium tuberculosis makes the development of novel anti-tubercular compounds and the identification of alternative mycobacterial drugable targets urgent priorities. Recently, type VII secretion systems (T7SS) have been discovered in mycobacteria. The genome of M. tuberculosis encodes 5 of such systems (ESX-1 to -5), three of which have been characterized and shown to be essential for viability (ESX-3, ESX-5) or virulence (ESX-1, ESX-5). Because of their crucial role in host-pathogen interactions as well as their involvement in basic biological processes of tubercle bacilli, T7SS/ESX represent promising targets for novel anti-tuberculosis drugs. Here, we review the current knowledge of the T7SS/ESX and their impact on M. tuberculosis physiology and virulence. Finally, we discuss the possible approaches to develop T7SS/ESX inhibitors. © 2014 Bentham Science Publishers
Targeting Type VII/ESX Secretion Systems for Development of Novel Antimycobacterial Drugs.
No full text
The PPE domain of PPE17 is responsible for its surface localization and can be used to express heterologous proteins on the mycobacterial surface.
No full text
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
- …
