43 research outputs found
Studies on CheA(B): Phosphorylation, methylation and behavioral control during chemotactic signal transduction in Bacillus subtilis
No full textChemotaxis in Bacillus subtilis is a prototypical behavior and signal transduction process, and CheA\sb{\rm B} plays an important role in it. The cheA\sb{\rm B} gene was isolated, sequenced, expressed and mutated. It encoded a large negatively charged protein with a molecular weight of approximately 74,000. The predicted protein sequence has 33% homology with the Escherichia coli and CheA\sb{\rm E}. Such proteins have been found to autophosphorylate and are members of the same histidine kinase signal modulating family. CheA\sb{\rm B} has several conserved regions (including the histidine that is phosphorylated in CheA\sb{\rm E}) that coincide with the other autophosphorylated signal transducers. In vitro experiments on partially purified CheA\sb{\rm B} indicates that it also appears to autophosphorylate. CheA\sb{\rm E} mediates the effect of binding of attractants or repellents at the MCPs (receptors) by altering its rate of autophosphorylation and subsequent phosphorylation of CheY, to bring about behavioral change, and CheB, to bring about adaptation. CheA\sb{\rm B} appears to play a similar central controlling role, for a null mutant and all point mutants tested were defective in attractant-induced methanol production and showed no behavioral response upon addition of chemoeffectors. Furthermore, methylation of the MCPs, in which methyl groups are transferred away to an acceptor and replaced by methyl groups from S-adenosylmethionine, is regulated by CheB\sb{\rm B}, whose activity is controlled by CheA\sb{\rm B}.Although the chemotactic mechanism in B. subtilis thus appears to involve phosphoryl transfer, it is significantly different from that in E. coli. First, the cheA\sb{\rm B} null mutant mostly tumbles, whereas cheA\sb{\rm E} mutants swim smoothly. Since the null mutant in cheY\sb{\rm B} also tumbles whereas that in cheY\sb{\rm E} swims smoothly, it is likely that CheY\sb{\rm B}-P causes smooth swimming, whereas CheY\sb{\rm E}-P is known to cause tumbling. Second, only in B. subtilis does excitation lead to methyl transfer and methanol formation, probably to help bring about adaptation, and CheA\sb{\rm B} controls this. It also is required for some, but not all, changes in methylation of MCPs following addition of the attractant aspartate. All of these experiments suggest a unique mechanism for chemotaxis in B. subtilis.Made available in DSpace on 2011-05-07T14:20:44Z (GMT). No. of bitstreams: 2
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Biochemistry and regulation of CheA in Bacillus subtilis chemotaxis
No full textBacterial chemotaxis is one of the most well understood signal transduction processes in biology. By controlling the direction of flagella rotation, this process allows the organism to sense changes in its surroundings and migrate toward more favorable environments. The process of chemotaxis is controlled by the activity of an autophosphorylating histidine kinase, CheA. The work described in this thesis shows that Bacillus subtilis CheA differs from other members of this family of bacterial histidine kinases in two respects: it is able to achieve its maximum phosphorylation potential at very low ATP concentrations, and the phosphorylated form of the enzyme is very stable in the presence of ADP and other potential phosphoryl group acceptors. We have long hypothesized that attractant-bound methyl-accepting chemotaxis proteins (MCPs) in B. subtilis increase the activity of CheA. Asparagine-bound McpB has been shown here to increase CheA activity in vitro, the first example of activation of a two-component signal transducing kinase by its proposed environmental ligand to date. Studies on the enteric chemotaxis system revealed that taxis toward certain sugars is mediated solely through a separate phosphoenolpyruvate-dependent phosphotransferase system (PTS), involved in sugar transport. In B. subtilis, we have determined that taxis toward PTS carbohydrates is mediated both by MCPs and the PTS. Finally, a restriction map of the distal end of the 26kb fla/che operon has been deduced, which will be of value in attempts to clone additional chemotaxis genes in B. subtilis.Made available in DSpace on 2011-05-07T12:51:56Z (GMT). No. of bitstreams: 2
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Genome sequence of Rhodobacter sphaeroides strain WS8N
No full textCopyright © 2011, American Society for MicrobiologyRhodobacter sphaeroides is a metabolically diverse photosynthetic alphaproteobacterium found ubiquitously in soil and freshwater habitats. Here we present the annotated genome sequence of R. sphaeroides WS8N.This research was funded by the UK Biotechnology and Biological Sciences Research Council
Resilience and Vulnerability Assessment as the Basis for Adaptation Dialogue in Information-Poor Environments: A Cambodian Example
No full text
Perspectivas interdisciplinarias: contribuciones significativas desde el campo editorial, la ilustración y el emprendimiento al medio cultural
No full textA lo largo de su trayectoria como diseñadora gráfica profesional, la
autora del presente informe incursiona en diversos sectores del mercado
laboral, destacándose especialmente en el diseño editorial y el branding. El
objetivo principal de este informe es recapitular y respaldar su desempeño
profesional alineado con sus motivaciones personales. En el presente
documento se detallan, de manera concisa, tres proyectos seleccionados que
abarcan los últimos siete años de su carrera. En primer lugar, se analiza el rol
desempeñado en el diseño editorial para más de veinte publicaciones bajo el
sello editorial del Fondo de Cultura Económica (Perú), utilizando cuatro como
ejemplos, y se destaca cómo esta experiencia ha constituido una plataforma
de aprendizaje para proyectos futuros. Seguidamente, se explor en detalle su
contribución al diseño de marca, planificación, conceptualización y gestión de
contenido para el perfil de Instagram de Vuelo Ámbar Print Studio, espacio
especializado en grabado y letterpress y cofundado por la autora, Giselle
Adrianzén, junto con Diego Cabanillas, (grabador de la PUCP), resaltando
también su labor como directora artística para diversos proyectos. Por último,
se examina su aporte como ilustradora editorial para la reedición del libro
"Autobiografía de un Yogui" de Paramahansa Yogananda, destacando cómo
sus ilustraciones enriquecen la interpretación reflexiva del lector, según la
editora del proyecto, Cindy Torrejón. Cada proyecto está respaldado con
material gráfico que ilustra los resultados del diseño, detallando la
metodología empleada para fundamentar sus aspectos estéticos,
comunicacionales, técnicos y funcionales.Throughout her career as a professional graphic designer, the author of
this report has ventured into various sectors of the job market, particularly
excelling in editorial design and branding. The main objective of this report is
to recapitulate and support her professional performance aligned with her
personal motivations. This document will detail, concisely, three selected
projects spanning the last seven years of her career. Firstly, the role played in
editorial design for over twenty publications under the editorial imprint of Fondo
de Cultura Económica (Peru) will be analyzed, utilizing four as examples, and
emphasizing how this experience has served as a learning platform for future
projects. Subsequently, her contribution to brand design, planning,
conceptualization, and content management for the Instagram profile of Vuelo
Ámbar Print Studio, an studio specialized in engraving and letterpress cofounded by the author, Giselle Adrianzén, alongside Diego Cabanillas
(engraver from PUCP), will be explored in detail, also highlighting her role as
artistic director for various projects. Finally, her contribution as an editorial
illustrator for the reissue of "Autobiography of a Yogi" by Paramahansa
Yogananda will be examined, emphasizing how her illustrations enriched the
reflective interpretation of the reader, according to the project's editor, Cindy
Torrejón. Each project is supported by graphical material illustrating the design
results, detailing the methodology used to support its aesthetic,
communicational, technical, and functional aspects
Perspectivas interdisciplinarias: contribuciones significativas desde el campo editorial, la ilustración y el emprendimiento al medio cultural
No full textA lo largo de su trayectoria como diseñadora gráfica profesional, la
autora del presente informe incursiona en diversos sectores del mercado
laboral, destacándose especialmente en el diseño editorial y el branding. El
objetivo principal de este informe es recapitular y respaldar su desempeño
profesional alineado con sus motivaciones personales. En el presente
documento se detallan, de manera concisa, tres proyectos seleccionados que
abarcan los últimos siete años de su carrera. En primer lugar, se analiza el rol
desempeñado en el diseño editorial para más de veinte publicaciones bajo el
sello editorial del Fondo de Cultura Económica (Perú), utilizando cuatro como
ejemplos, y se destaca cómo esta experiencia ha constituido una plataforma
de aprendizaje para proyectos futuros. Seguidamente, se explor en detalle su
contribución al diseño de marca, planificación, conceptualización y gestión de
contenido para el perfil de Instagram de Vuelo Ámbar Print Studio, espacio
especializado en grabado y letterpress y cofundado por la autora, Giselle
Adrianzén, junto con Diego Cabanillas, (grabador de la PUCP), resaltando
también su labor como directora artística para diversos proyectos. Por último,
se examina su aporte como ilustradora editorial para la reedición del libro
"Autobiografía de un Yogui" de Paramahansa Yogananda, destacando cómo
sus ilustraciones enriquecen la interpretación reflexiva del lector, según la
editora del proyecto, Cindy Torrejón. Cada proyecto está respaldado con
material gráfico que ilustra los resultados del diseño, detallando la
metodología empleada para fundamentar sus aspectos estéticos,
comunicacionales, técnicos y funcionales.Throughout her career as a professional graphic designer, the author of
this report has ventured into various sectors of the job market, particularly
excelling in editorial design and branding. The main objective of this report is
to recapitulate and support her professional performance aligned with her
personal motivations. This document will detail, concisely, three selected
projects spanning the last seven years of her career. Firstly, the role played in
editorial design for over twenty publications under the editorial imprint of Fondo
de Cultura Económica (Peru) will be analyzed, utilizing four as examples, and
emphasizing how this experience has served as a learning platform for future
projects. Subsequently, her contribution to brand design, planning,
conceptualization, and content management for the Instagram profile of Vuelo
Ámbar Print Studio, an studio specialized in engraving and letterpress cofounded by the author, Giselle Adrianzén, alongside Diego Cabanillas
(engraver from PUCP), will be explored in detail, also highlighting her role as
artistic director for various projects. Finally, her contribution as an editorial
illustrator for the reissue of "Autobiography of a Yogi" by Paramahansa
Yogananda will be examined, emphasizing how her illustrations enriched the
reflective interpretation of the reader, according to the project's editor, Cindy
Torrejón. Each project is supported by graphical material illustrating the design
results, detailing the methodology used to support its aesthetic,
communicational, technical, and functional aspects
Author response
No full textMost motile bacteria sense and respond to their environment through a transmembrane chemoreceptor array whose structure and function have been well-studied, but many species also contain an additional cluster of chemoreceptors in their cytoplasm. Although the cytoplasmic cluster is essential for normal chemotaxis in some organisms, its structure and function remain unknown. Here we use electron cryotomography to image the cytoplasmic chemoreceptor
cluster in Rhodobacter sphaeroides and Vibrio cholerae. We show that just like transmembrane arrays, cytoplasmic clusters contain trimers-of-receptor-dimers organized in 12-nm hexagonal arrays. In contrast to transmembrane arrays, however, cytoplasmic clusters comprise two CheA/
CheW baseplates sandwiching two opposed receptor arrays. We further show that cytoplasmic fragments of normally transmembrane E. coli chemoreceptors form similar sandwiched structures in the presence of molecular crowding agents. Together these results suggest that the 12-nm
hexagonal architecture is fundamentally important and that sandwiching and crowding can replace the stabilizing effect of the membrane
Gender Equity: Employment and Performance
No full textGender performativity refers to the productivity of labor based on worker gender. Performativity affects employability and can be categorized into various aspects for study based on age group, gender, job type, and other factors. Gender performativity can indirectly refer to ability and opportunities based on performance. Gender inequality issues have been on the map as a global concern raised in international talks, in forums, and by delegates around the world. The question of equality treatment between genders has become more evident over recent years because of modernization and the era of globalization (Cailin and Leanne 2015). The significant role and contribution of women cannot be ignored, because they do significantly increase the wealth and assist the growth of a household, a firm, and even a country. As a group, women work as much as men, if not more. When both paid and unpaid work such as household chores and caring for children are taken into account, women work... (Abstract by author
Using structural information to change the phosphotransfer specificity of a two-component chemotaxis signalling complex.
No full textaddresses: Oxford Centre for Integrative Systems Biology, Department of Biochemistry, University of Oxford, Oxford, United Kingdom.notes: PMCID: PMC2817712types: Journal Article; Research Support, Non-U.S. Gov'tCopyright: © 2010 Bell et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Two-component signal transduction pathways comprising histidine protein kinases (HPKs) and their response regulators (RRs) are widely used to control bacterial responses to environmental challenges. Some bacteria have over 150 different two-component pathways, and the specificity of the phosphotransfer reactions within these systems is tightly controlled to prevent unwanted crosstalk. One of the best understood two-component signalling pathways is the chemotaxis pathway. Here, we present the 1.40 A crystal structure of the histidine-containing phosphotransfer domain of the chemotaxis HPK, CheA(3), in complex with its cognate RR, CheY(6). A methionine finger on CheY(6) that nestles in a hydrophobic pocket in CheA(3) was shown to be important for the interaction and was found to only occur in the cognate RRs of CheA(3), CheY(6), and CheB(2). Site-directed mutagenesis of this methionine in combination with two adjacent residues abolished binding, as shown by surface plasmon resonance studies, and phosphotransfer from CheA(3)-P to CheY(6). Introduction of this methionine and an adjacent alanine residue into a range of noncognate CheYs, dramatically changed their specificity, allowing protein interaction and rapid phosphotransfer from CheA(3)-P. The structure presented here has allowed us to identify specificity determinants for the CheA-CheY interaction and subsequently to successfully reengineer phosphotransfer signalling. In summary, our results provide valuable insight into how cells mediate specificity in one of the most abundant signalling pathways in biology, two-component signal transduction
