Cristal·lització de la lipoxigenasa de "Pseudomonas aeruginosa" 42A2 i estudi filogenètic de les subfamílies de les lipoxigenases (Tesi)

[cat] Les lipoxigenases són conegudes com les responsables de la catàlisi d'oxigenació molecular d’àcids grassos poli-insaturats que forma un producte hydroperoxid (tòxic) que es pot convertir en una gran varietat de metabòlits secundaris. Durant anys, la presència de lipoxgenases ha estat descrita únicament en organismes eucariotes, mamífers, plantes, petits invertebrats marins i fongs. La funció biològica de les lipoxigenases eucariotes ha estat àmpliament estudiada. Estan involucrades en la síntesi de molècules de senyalització com els leucotriens, en mamífers, o en la de l’àcid jasmònic, en plantes. L’any 1964, Shimahara, publicava la presència d’una lipoxigenasa en un bacteri gram-negatiu aïllat de les escombraries. Encara avui són poques les informacions referents a lipoxigenases bacterianes que s'han publicat, alguns exemples són les de Thermoactinomyces vulgaris, Pseudomonas i Nostoc punctiforme. Els anàlisis que s’han realitzat utilitzant el programa BLAST, indiquen que hi ha gens “LOX-like” en Shewanella, Burkolderia, Nitrosomonas i Myxococcus, però la funció biològica de lipoxigenases procariotes encara no s'ha aclarit. No obstant, les lipoxigenases publicades en la base de dades “gene data-bank” són d’organismes ambientals de medi marí i de sòls, això suggereix que les lipoxigenases poden tenir un paper important en la biodegradació. En aquest estudi es reporta la primera estructura molecular d'una lipoxigenasa procariota i un estudi preliminar de la filogènia d’aquest grup de proteïnes.[eng] The lipoxygenases are known as responsible for the reaction of oxygenation of poly-unsaturated fatty acid producing hydroperoxid acids (toxic) that can be converted into a different secondary metabolites. For years, the presence of lipoxygenases has been described only in eukaryotes, mammals, plants, fungi and small invertebrates. The biological function of eukaryotic lipoxygenases has been widely studied. They are involved in the synthesis of leukotrienes as signaling molecules in mammals, or in the jasmonic acid in plants. In 1964, Shimahara, published the existence of lipoxygenases of gram-negative bacteria isolated from the trash. Even today there are few data concerning bacterial lipoxygenases published. Some examples are those of Thermoactinomyces vulgaris, Pseudomonas and Nostoc punctiforme. The analysis were performed using the BLAST program and the results indicate that there are "LOX-like" genes in Shewanella, Burkolderia, Nitrosomonas and Myxococcus, but the biological function of prokaryotic lipoxygenases is not yet clear. However, lipoxygenases published in the database "gene data-bank" are marine organisms and environmental grounds, suggesting that the lipoxygenases can play an important role in biodegradation. This study reports the first molecular structure of a prokaryotic lipoxygenasa and a preliminary study of the phylogeny of this group of proteins

Crystallization and resolution of the lipoxygenase of Pseudomonas aeruginosa 42A2 and phylogenetic study of the subfamilies of the lipoxygenases

Podeu consultar el llibre complet a: http://hdl.handle.net/2445/32392Lipoxygenases are non-heme iron enzymes essential in eukaryotes, where they catalyze the formation of the fatty acid hydroperoxides that are required by a large diversity of biological and pathological processes. In prokaryotes, most of them totally lacking in polyunsaturated fatty acids, the possible biological roles of lipoxygenases have remained obscure. In this study, it is reported the crystallization of a lipoxygenase of Pseudomonas aeruginosa (Pa_LOX), the first from a prokaryote. High resolution data has been acquired which is expected to yield structural clues to the questions adressed. Besides, a preliminar phylogenetic analysis using 14 sequences has confirmed the existence of this subfamily of bacterial lipoxygenases, on one side, and a greater diversity than in the corresponding eukaryotic ones, on the other. Finally, an evolutionary study of bacterial lipoxygenases on the same set of lipoxygenases, show a selection pressure of a basically purifying or neutral character except for a single aminoacid, which would have been selected after a positive selection event

Crystallization and resolution of the lipoxygenase of Pseudomonas aeruginosa 42A2 and phylogenetic study of the subfamilies of the lipoxygenases

Podeu consultar el llibre complet a: http://hdl.handle.net/2445/32392Lipoxygenases are non-heme iron enzymes essential in eukaryotes, where they catalyze the formation of the fatty acid hydroperoxides that are required by a large diversity of biological and pathological processes. In prokaryotes, most of them totally lacking in polyunsaturated fatty acids, the possible biological roles of lipoxygenases have remained obscure. In this study, it is reported the crystallization of a lipoxygenase of Pseudomonas aeruginosa (Pa_LOX), the first from a prokaryote. High resolution data has been acquired which is expected to yield structural clues to the questions adressed. Besides, a preliminar phylogenetic analysis using 14 sequences has confirmed the existence of this subfamily of bacterial lipoxygenases, on one side, and a greater diversity than in the corresponding eukaryotic ones, on the other. Finally, an evolutionary study of bacterial lipoxygenases on the same set of lipoxygenases, show a selection pressure of a basically purifying or neutral character except for a single aminoacid, which would have been selected after a positive selection event