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Enzymes or signals? Functional characterization of Pseudomonas aeruginosa HD-GYP phosphodiesterases involved in the homeostasis of the second messenger c-di-GMP
Get PDFInhibition Of Bacterial Biofilms: New Molecular Strategies Targeting Cyclic-Di-GMP Metabolism.
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Metabolism of cyclic-di-GMP in bacterial biofilms: From a general overview to biotechnological applications
No full textBacteria exist in nature in a planktonic single-cell state or in a sessile multicellular state, the biofilm. In the latter state, the bacterial community optimizes the cell-environment and cell-cell communication strategies. Biofilms are widely diffuse in many industrial, environmental and clinical settings and are less sensitive to treatments with antimicrobial agents compared to planktonic cells. Biofilms formed by bacterial pathogens, such as those formed by Pseudomonas aeruginosa in immunocompromised patients, have a high impact on public health.
The switch between the planktonic and the biofilm lifestyle is strictly regulated by the second messenger 3', 5'-cyclic diguanylic acid (c-di-GMP). The intracellular levels of this molecule are controlled by two classes of enzymes: diguanylate cyclases (DGC) and phosphodiesterases (PDE). In this review we report the structural and functional data available to date on these enzymes and we summarize the possible medical, environmental and industrial biotechnological applications involving bacterial c-di-GMP metabolism
The catalytic mechanism of Pseudomonas aeruginosa cd1 nitrite reductase
No full textThe cd1 NiRs (nitrite reductases) are enzymes catalysing the reduction of nitrite to NO (nitric oxide) in the bacterial energy conversion denitrification process. These enzymes contain two distinct redox centres: one covalently bound c-haem, which is reduced by external electron donors, and another peculiar porphyrin, the d1-haem (3,8-dioxo-17-acrylate- porphyrindione), where nitrite is reduced to NO. In the present paper, we summarize the most recent results on the mechanism of nitrite reduction by the cd1 NiR from Pseudomonas aeruginosa. We discuss the essential catalytic features of this enzyme, with special attention to the allosteric regulation of the enzyme's activity and to the mechanism employed to avoid product inhibition, i.e. trapping of the active-site reduced haem by the product NO. These results shed light on the reactivity of cd1 NiRs and assign a central role to the unique d1-haem, present only in this class of enzymes. ©The Authors Journal compilation ©2011 Biochemical Society
BIOFILM FORMATION IN THE HUMAN PATHOGEN PSEUDOMONAS AERUGINOSA: A STRUCTURAL BIOLOGY STUDY OF PROTEINS INVOLVED IN c-diGMP HOMEOSTASIS
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Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
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