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180 results on '"Monasterio, Octavio"'

1. A tribute to Dr. Serge N. Timasheff, our mentor

Author

Aune, Kirk, Lee, James, Prakash, V, Bhat, Rajiv, Andreu, Jose, Monasterio, Octavio, Perez-Ramirez, Bernardo, Shearwin, Keith, Arakawa, Tsutomu, Carpenter, John, Crowe, John, Crowe, Lois, Somero, George, Gagnon, Pete, and Charles, Marina Timasheff

Subjects
Medical and Biological Physics, Biochemistry and Cell Biology, Physical Sciences, Biological Sciences, Other Physical Sciences, Medical Physiology, Biochemistry and cell biology, Medical and biological physics
Abstract

Dr. Serge N. Timasheff, our mentor and friend, passed away in 2019. This article is a collection of tributes from his postdoctoral fellows, friends, and daughter, who all have been associated with or influenced by him or his research. Dr. Timasheff is a pioneer of research on thermodynamic linkage between ligand interaction and macromolecular reaction. We all learned a great deal from Dr. Timasheff, not only about science but also about life.

Published
2021

11. The production in vivo of microcin E492 with antibacterial activity depends on salmochelin and EntF

Author

Mercado, Gabriela, Tello, Mario, Marin, Macarena, Monasterio, Octavio, and Lagos, Rosalba

Subjects
Antibacterial agents -- Research, Bacteriocins -- Properties, Biological sciences
Abstract

Microcin E492 is a channel-forming bacteriocin that is found in two forms, namely, a posttranslationally modified form obtained by the covalent linkage of salmochelin-like molecules to serine 84 and an unmodified form. The production of modified microcin E492 requires the synthesis of enterochelin, which is subsequently glycosylated by MceC and converted into salmochelin, mceC mutants produced inactive microcin E492, and this phenotype was reversed either by complementation with iroB from Salmonella enterica or by the addition of exogenous salmochelin. Cyclic salmochelin uptake by Escherichia coli occurred mainly through the outer membrane catecholate siderophore receptor Fiu. The production of inactive microcin E492 by mutants in entB and entC was reverted by the addition of the end product of the respective mutated pathway (2,3-dihydroxybenzoic acid and enterochelin/salmochelin, respectively), while mutants in entF did not produce active microcin E492 in the presence of enterochelin or salmochelin. The EntF adenylation domain was the only domain required for this microcin E492 maturation step. Inactivation of the enzymatic activity of this domain by site-directed mutagenesis did not prevent the synthesis of active microcin E492 in the presence of salmochelin, indicating that the adenylation activity is not essential for the function of EntF at this stage of microcin E492 maturation.

Published
2008

15. Identification and properties of the genes encoding microcin E492 and its immunity protein

Author

Lagos, Rosalba, Villanueva, Jorge E., and Monasterio, Octavio

Subjects
Klebsiella -- Genetic aspects, Genetic regulation -- Research, Biological sciences
Abstract

Research was conducted to identify the genes encoding microcine E492, a low-molecular-weight channel-forming bacteriocin generated by a strain of Klebsiella pneumoniae, and to study its properties and immunity protein. Results indicate that the immunity protein was associated with the inner membrane. Analysis of the DNA sequence suggests that the genes belong to the same family as microcin 24 and that they do not share structural motifs with any other known channel-forming bacteriocin.

Published
1999

19. Calcium and gadolinium ions stimulate the GTPase activity of purified chicken brain tubulin through a conformational change

Author

Soto, Claudio, Rodriguez, Patricio H., and Monasterio, Octavio

Subjects
Tubulins -- Research, Proteins -- Conformation, Enzyme activation -- Analysis, Polymerization -- Research, Biological sciences, Chemistry
Abstract

A conformational change mediates the suppression of tubulin polymerization and the stimulation of GTPase activity by Ca2+. GTPase activity exhibits a saturation point in the presence of Ca2+ and Gd3+ and varies directly with tubulin concentration between 0.9 and 31.8 micro-M in the presence of Ca2+. GTPase activity is related to the mechanism of suppression of tubulin assembly by Ca2+ though the activity has no involvement in the suppression. The inhibition is probably due to the formation by Ca2+ of a nonfunctional conformational state of tubulin that shows GTPase activity.

Published
1996

24. Evaluating Different Virulence Traits of Klebsiella pneumoniae Using Dictyostelium discoideum and Zebrafish Larvae as Host Models

Author

Marcoleta, Andrés E., primary, Varas, Macarena A., additional, Ortiz-Severín, Javiera, additional, Vásquez, Leonardo, additional, Berríos-Pastén, Camilo, additional, Sabag, Andrea V., additional, Chávez, Francisco P., additional, Allende, Miguel L., additional, Santiviago, Carlos A., additional, Monasterio, Octavio, additional, and Lagos, Rosalba, additional

Published
2018
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33. Tau induces ring and microtubule formation from alpha beta -tubulin dimers under nonassembly conditions

Author

Devred, Francois, Barbier, Pascale, Douillard, Soazig, Monasterio, Octavio, Andreu, Jose Manuel, and Peyrot, Vincent

Subjects
Binding proteins -- Chemical properties, Microtubules -- Influence, Chemistry, Analytic, Biological sciences, Chemistry
Abstract

Tau is a neuronal microtubule- associated protein that plays a central role in many cellular processes, both physiological and pathological, such as axons stabilization and Alzheimer's disease. A new insight into the mechanisms is gained by which tau binds to tubulin and induces microtubule formation.

Published
2004

39. Reversible unfolding of FtsZ cell division proteins from archaea and bacteria. Comparison with eukaryotic tubulin folding and assembly

Author

Andreu, José Manuel, Oliva, María A., Monasterio, Octavio, Comunidad de Madrid, Fondo Nacional de Desarrollo Científico y Tecnológico (Chile), Andreu, José Manuel, Oliva, María A., Andreu, José Manuel [0000-0001-8064-6933], and Oliva, María A. [0000-0002-2215-4639]

Subjects
Ring, Self-association, Methanococcus-jannaschii, bacteria, Alpha-beta-tubulin, Microtubule, macromolecular substances, Escherichia-coli, Binding, gtp hydrolysis, actin, Chaperonin
Abstract

10 p.-7 fig.1 tab., The stability, refolding, and assembly properties of FtsZ cell division proteins from Methanococcus jannaschii and Escherichia coli have been investigated. Their guanidinium chloride unfolding has been studied by circular dichroism spectroscopy. FtsZ from E. coli and tubulin released the bound guanine nucleotide, coinciding with an initial unfolding stage at low denaturant concentrations, followed by unfolding of the apoprotein. FtsZ from M. jannaschii released its nucleotide without any detectable secondary structural change. It unfolded in an apparently two-state transition at larger denaturant concentrations. Isolated FtsZ polypeptide chains were capable of spontaneous refolding and GTP-dependent assembly. The homologous eukaryotic tubulin monomers misfold in solution, but fold within the cytosolic chaperonin CCT. Analysis of the extensive tubulin loop insertions in the FtsZ/tubulin common core and of the intermolecular contacts in model microtubules and tubulin-CCT complexes shows a loop insertion present at every element of lateral protofilament contact and at every contact of tubulin with CCT (except at loop T7). The polymers formed by purified FtsZ have a distinct limited protofilament association in comparison with microtubules. We propose that the loop insertions of tubulin and its CCT-assisted folding coevolved with the lateral association interfaces responsible for extended two-dimensional polymerization into microtubule polymers., This work was supported in part by MCyT Grant BIO99-0859-C03-02/BIO2000-0748, the Programa de Grupos Estratégicos de la Comunidad de Madrid (to J. M. A.), an FPI predoctoral fellowship (to M. A. O.), and FONDECYT Grant 1010848 (to O. M.).

Published
2002

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