158 research outputs found
Promiscuous behaviour of the bacterial metallohydrolase DapE : an evolutionary and mechanistic perspective
No full textEnzyme promiscuity, defined as functional properties other than those for which they are evolved, is considered a key factor in the evolution of new enzyme functions. Many metalloproteins can be alternatively metallated, which may lead to metal-dependent promiscuity. The mechanisms and evolutionary implications of metal-mediated promiscuity appear to be underexplored, especially considering that approximately one-third of structurally characterized proteins are thought to be metalloproteins.
Here, we investigated the bacterial binuclear metallohydrolase, N-Succinyl-L-LDiaminopimelic acid desuccinylase DapE (EC 3.5.1.18) of S.enterica. DapE is an essential enzyme in the late stage of the lysine biosynthetic pathway that also provides a crucial building block of the peptidoglycan cell wall. Since DapE is essential for most Gram-negative and many Gram-positive bacteria and it is not present in humans, it has been proposed as a very good target for antibiotic development. It was also reported that DapE has a metal dependent promiscuous aspartyl dipeptidase activity, in which incorporation of either zinc or manganese to the enzyme leads to activity with different substrates and this phenomenon occurs both in vivo and in vitro.
We addressed the reaction mechanism of the native desuccinylase activity as well as the Mn2+-dependent aspartyl dipeptidase promiscuous activity of DapE, by investigating a series of substrate analogues and potential inhibitors. We postulated a plausible mechanism for metal-dependent promiscuity, based on subtle differences in coordination preferences between Mn2+ and Zn2+,which may be widely applicable to other enzymes. We revealed why a promising inhibitor of the enzyme in vitro, L-captopril, fails to exert antibiotic activity and
propose broad practical implications of this discovery for drug-design, as well as fundamental evolutionary implications. We described kinetic cooperativity in DapE, which offers clues on structural rearrangements that occur during catalysis and is also of relevance to inhibitor design.
Finally, we explored the evolutionary aspects of functional robustness of native activity over the promiscuous activity using DapE as a model enzyme and addressed the molecular mechanisms underlying the emergence of functional robustness through laboratory evolution
Construcció de set vivendes unifamiliars en filera a l'avinguda Pau Casals de Santes Creus i rehabilitació del centre cívic de Santes Creus
No full textEl present Projecte de Final de Carrera té per objectiu de realitzar una pràctica d’obra que consta de dues parts : el seguiment de la construcció de set cases en filera a Santes Creus i el seguiment de la rehabilitació del Centre Cívic de la mateixa població. Les dues obres a estudiar estan a la població de Santes Creus, ubicada a la llera del riu Gaià forma part del municipi d’Aiguamúrcia, que es troba situat a la comarca de l’Alt Camp. Vista de Santes Creus des de la carretera del Pont d’Armentera : La presència del Monestir de Santes Creus fa que totes les edificacions, tant de nova construcció com de rehabilitació estiguin afectades pel “ Pla especial de protecció del Monestir de Santes Creus i el seu entorn“ que en desenvolupa una normativa específica
Construcció de set vivendes unifamiliars en filera a l'avinguda Pau Casals de Santes Creus i rehabilitació del centre cívic de Santes Creus
No full textEl present Projecte de Final de Carrera té per objectiu de realitzar una pràctica d’obra que consta de dues parts : el seguiment de la construcció de set cases en filera a Santes Creus i el seguiment de la rehabilitació del Centre Cívic de la mateixa població. Les dues obres a estudiar estan a la població de Santes Creus, ubicada a la llera del riu Gaià forma part del municipi d’Aiguamúrcia, que es troba situat a la comarca de l’Alt Camp. Vista de Santes Creus des de la carretera del Pont d’Armentera : La presència del Monestir de Santes Creus fa que totes les edificacions, tant de nova construcció com de rehabilitació estiguin afectades pel “ Pla especial de protecció del Monestir de Santes Creus i el seu entorn“ que en desenvolupa una normativa específica
Experimental and guided theoretical investigation of complex reaction mechanisms in a prins reaction of glyoxylic acid and isobutene
No full text(Chemical Equation Presented) A laboratory experiment was designed for undergraduate students, in which the outcome of an easy single-step organic synthesis with well-defined conditions was not elucidated until the end of the exercise. In class, students predict and discuss the possible products using their knowledge of reaction mechanisms. In the laboratory, they learn how to carry out a reaction safely with gaseous isobutene, and to isolate and identify the two main products. The class and the laboratory components are completed in 10 h, including laboratory time of 6 to 7 h, divided in two sessions. The class-component could also be implemented independently as a theoretical exercise in a "virtual experiment" simply by presenting the methods and results to students using a guided-inquiry approach, appropriate for a standard 3 h undergraduate class. The finding that the simple reaction leads to a largely unexpected product, together with open discussions with students covering several theoretical aspects applicable to this reaction, helps to promote critical thinking and to provide an effective educational tool to better understand the process of scientific research in chemistry
Metal-dependent inhibition and substrate promiscuity in metallo-deacylases
No full textInhibitors of Histone Deacetylases enzymes (HDACs) are attractive anticancer compounds because HDACs are directly involved in post translational modifications of proteins, for example, the acetylation of histone lysine residues alters interactions with the DNA backbone. Several classes of HDACs are known to be hydrolytic metalloenzyme that can exhibit a wide range of catalytic activities when substituted with different transition metal ions, indeed different metal ions in metalloenzymes can affect enzyme function by maintaining the structure of the active site, but providing alternative coordination interactions for substrate, transitions states and intermediates. We are exploring the behavior of metalloisomorfs of bacterial N-succinyl-l,l-diaminopimelic acid desuccinylase (dapE), a model metallohydrolase with similarities to HDACs. A deeper understanding of the substrate binding-mode on the metal catalytic active site and a closer look to the coordination chemistry of different metals, would allow us to design new possible substrates and inhibitors of dapE and therefore have an insights into the molecular interactions of metal-targeting compounds with zinc dependent metalloenzymes that may assist the design of drug compounds and potentially provide new strategies to overcome drug-resistance
Selectivity of Inhibition of N-Succinyl-L, L-diaminopimelic acid desuccinylase in bacteria : the product of dapE-gene is not the target of L-Captopril antimicrobial activity
No full textJournal Menu Abstracting and Indexing Aims and Scope Annual Issues Article Processing Charges Articles in Press Author Guidelines Bibliographic Information Contact Information Editorial Board Editorial Workflow Free eTOC Alerts Reviewers Acknowledgment Subscription Information Open Special Issues Published Special Issues Special Issue Guidelines Abstract Full-Text PDF Full-Text HTML Linked References How to Cite this Article Bioinorganic Chemistry and ApplicationsVolume 2011 (2011), Article ID 306465, 6 pagesdoi:10.1155/2011/306465Research ArticleSelectivity of Inhibition of N-Succinyl-L,L-Diaminopimelic Acid Desuccinylase in Bacteria: The product of dapE-gene Is Not the Target of L-Captopril Antimicrobial ActivityNarasimha Rao Uda and Marc CreusDepartment of Chemistry, University of Basel, Spitalstrasse 51, Basel 4056, SwitzerlandReceived 22 December 2010; Accepted 21 January 2011Academic Editor: Zheng Dong Copyright © 2011 Narasimha Rao Uda and Marc Creus. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.AbstractThe emergence of bacterial strains that are resistant to virtually all currently available antibiotics underscores the importance of developing new antimicrobial compounds. N-succinyl-L,L-diaminopimelic acid desuccinylase (DapE) is a metallohydrolase involved in the meso-diaminopimelate (mDAP)/lysine biosynthetic pathway necessary for lysine biosynthesis and for building the peptidoglycan cell wall. Because DapE is essential for Gram-negative and some Gram-positive bacteria, DapE has been proposed as a good target for antibiotic development. Recently, L-captopril has been suggested as a lead compound for inhibition of DapE, although its selectivity for this enzyme target in bacteria remains unclear (Gillner et al. (2009)). Here, we tested the selectivity of L-captopril against DapE in bacteria. Since DapE knockout strains of gram-negative bacteria are viable upon chemical supplementation with mDAP, we reasoned that the antimicrobial activity of compounds targeting DapE should be abolished in mDAP-containing media. Although L-captopril had modest antimicrobial activity in Escherichia coli and in Salmonella enterica, to our surprise, inhibition of bacterial growth was independent both of mDAP supplementation and DapE over-expression. We conclude that DapE is not the main target of L-captopril inhibition in these bacteria. The methods implemented here will be useful for screening DapE-selective antimicrobial compounds directly in bacterial cultures
Les conferències arqueològiques de Teodor Creus a l'Ateneu de Vilanova i la Geltrú (1879)
No full textEn aquest article analitzem la figura de l'erudit Teodor Creus i Corominas (1827-1921) i la seva contribució a l'orientalística antiga a Catalunya. Concretament ens centrem en l'anàlisi del contingut de la seva obra La Arqueología y la Biblia, alhora que estudiem diverses notícies de premsa així com la seva correspondència conservada a la Biblioteca-Museu Víctor Balaguer per mirar de contextualitzar adequadament aquell treball en el seu marc històric.The aim of this article is to analyse the contribution of Teodor Creus i Corominas (1827-1921) to the development in Catalonia of Ancient Near Eastern Studies. The article delves into the content of his book La Arqueología y la Biblia, his press news and his letters housed in the Biblioteca-Museu Víctor Balaguer in order to place his work in its historical framework
Zinc-selective inhibition of the promiscuous bacterial amide-hydrolase DapE: Implications of metal heterogeneity for evolution and antibiotic drug design
No full textThe development of resistance to virtually all current antibiotics makes the discovery of new antimicrobial compounds with novel protein targets an urgent challenge. The dapE-encoded N-succinyl-l,l-diaminopimelic acid desuccinylase (DapE) is an essential metallo-enzyme for growth and proliferation in many bacteria, acting in the desuccinylation of N-succinyl-l,l- diaminopimelic acid (SDAP) in a late stage of the anabolic pathway towards both lysine and a crucial building block of the peptidoglycan cell wall. l-Captopril, which has been shown to exhibit very promising inhibitory activity in vitro against DapE and has attractive drug-like properties, nevertheless does not target DapE in bacteria effectively. Here we show that l-captopril targets only the Zn2+-metallo-isoform of the enzyme, whereas the Mn 2+-enzyme, which is also a physiologically relevant isoform in bacteria, is not inhibited. Our finding provides a rationale for the failure of this promising lead-compound to exhibit any significant antibiotic activity in bacteria and underlines the importance of addressing metallo-isoform heterogeneity in future drug design. Moreover, to our knowledge, this is the first example of metallo-isoform heterogeneity in vivo that provides an evolutionary advantage to bacteria upon drug-challenge. © 2014 The Royal Society of Chemistry
Astrospartus mediterraneus (Echinodermata: Ophiuroidea) in the Cap de Creus marine area: Ecological characterization of an emblematic species
No full textCurs 2018-2019A l’any 2016, es va començar a detectar un creixement poblacional mai abans observat
de l’espècie Astrospartus mediterraneus als caladors artesanals del Cap de Creus (Girona,
NO). És una espècie pertanyent a la classe Ophiuroidea, considerada la classe més diversa
del fílum dels equinoderms. Tanmateix, estem al capdavant d’una espècie poc coneguda
i amb poques observacions associades abans d’aquest creixement. És per això, que
l’objectiu d’aquest treball és aportar dades ecològiques sobre aquest ofiuroïdeu per tal
d’omplir els buits de coneixement d’aquesta espècie.
Entre l’abril i l’agost del 2018, en el marc del projecte MITICAP, es van fotografiar un
total de 466 individus que van ser pescats durant les sortides de pesca amb els pescadors
artesanals de les confraries de Cadaqués i del Port de la Selva, les fotografies dels quals
van ser analitzades per obtenir una estructura de talles de les poblacions de l’espècie i
també per obtenir la seva distribució geogràfica i batimètrica. A més, es va realitzar
l’enregistrament de 19 videotranssectes per mitjà de càmeres de vídeo ROV (Vehicle
submarí operat remotament) dels els quals es van analitzar amb l’objectiu d’obtenir la
seva distribució geogràfica i batimètrica a més d’obtenir la relació que estableix l’espècie
amb el medi on viu.
Aquest estudi aporta per primera vegada informació sobre la distribució geogràfica i
batimètrica, l’estructura de talles i sobre com A. mediterraneus es relaciona amb el medi
que l’envolta.
Els resultats obtinguts mostren que l’espècie té una àmplia distribució dins de la zona
mostrejada, on va ser detectada a partir dels 35 metres de profunditat, i que els individus
s’han trobat majoritàriament disposats sobre gorgònies. L’estructura de mides obtinguda
suggeriria que les poblacions d’ A. mediterraneus al Cap de Creus són relativament joves.
iv
Aquest estudi proporciona informació ecològica de l’espècie, la qual pot servir com a
referència per altres casos on també es vulgui estudiar l’Astrospartus mediterraneus.Since 2016, a population growth of Astrospartus mediterraneus was detected for the first
time in the Cap de Creus marine area (Girona, NW). This species belongs to Ophiuroidea
class, considered the largest class of Echinodermata Phylum. However, it is considered
an unknown basket star species with few observations in the area before the population
growth. Therefore, the aim of the study is to assess the ecology of this ophiuroid to deepen
the knowledge of this species.
Between April and August of 2018, within the framework of MITICAP project, 466
individuals which were by-catch during the artisanal fishing, were photographed and
analysed in order to obtain the size frequency distribution of its populations and obtain
the geographical and bathymetrical distribution. Moreover, 19 videotransects recorded by
means of ROV (Remoted Operated Vehicle) video cameras, were analysed to assess the
geographic and bathymetric distribution and determinate the relationship between
A.mediterraneus and the environment.
This study is the first work about the geographic, the bathymetric and the size frequency
distribution of the species and how it relates with the environment.
Results show that A. mediterraneus had a wide geographic distribution along the sampled
area, where it inhabits depths higher than 35 meters. All individuals were mainly found
over gorgonians and size structure suggests that A. mediterraneus populations are young.
This study provides ecological data about the study species potentially providing a
reference for other studies about Astrospartus mediterraneus
La creu d'or romànica de la Seu de Girona
No full textAl tresor de la catedral de Girona es
conserva un dels conjunts més notables
de creus d'ofebreria medievals de
Catalunya, que essencialment consisteix
en dues del segle XIV i una de principis
del XVI: la creu dita de les Confraries,
l'anomenada dels Esmalts i la creu d'or,
considerada la més valuosa en termes
materials i reservada per a les principals
festes de l'any. De creus i d'altres
objectes d'orfebreria litúrgica, però,
n'existiren d'altres al llarg de la història
de la seu que no han arribat fins als
nostres dies. Una d’aquestes és l'objecte
d'estudi d'aquest treball: una antiga creu
romànica d'or, antecessora de la darrera
que hem anomenat i tipològicament
emparentada amb la primera. Malgrat
haver desaparegut, va ser una obra de
gran importància per diferents raons que
mirarem d'explica
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