Publication: Organización bioquímica del proto-anillo de división bacteriano en sistemas mínimos de membrana: impacto del sistema MinCDE de selección del sitio de división
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2019-01-10
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Universidad Complutense de Madrid
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Abstract
La división celular bacteriana en E. coli está mediada por una maquinaría multiproteica (divisoma) cuyos componentes se ensamblan dinámicamente en el punto medio de la célula para formar el anillo de división, el cual desencadena la citocinesis bacteriana. El primer complejo macromolecular del divisoma es el proto-anillo constituido por tres proteínas, FtsZ, FtsA y ZipA, que se asocian a la membrana citoplasmática formando la estructura de andamiaje a la que se incorporan el resto de las proteínas esenciales de división. FtsZ es una GTPasa y su mecanismo de polimerización está estrechamente relacionado con la unión e hidrólisis de GTP. ZipA se estructura en un dominio transmembrana amino-terminal y un dominio globular C-terminal (zona de interacción con el central hub de FtsZ), conectados ambos por un segmento flexible. La proteína FtsA presenta homología estructural con la actina y consta de una corta hélice anfipática que permite su anclaje a la membrana. El posicionamiento del anillo Z está estrechamente regulado mediante varios sistemas de control negativo, con el fin de inhibir su incorrecta localización en la membrana bacteriana. Uno de ellos es el complejo de proteínas MinCDE, el cual oscila de polo a polo de la célula, bloqueando la polimerización de FtsZ en dichos polos...
Bacterial cell division in E. coli is mediated by a multiprotein machine whose elements interact dynamically at midcell to form the division ring, a structure that drives cytokinesis forming part of the divisome. The first macromolecular assembly of the divisome is the proto-ring, comprising three proteins – FtsZ, FtsA, and ZipA – that associate at the cytoplasmic membrane forming the scaffold structure into which the rest of the essential division proteins are incorporated. FtsZ is a GTPase and its polymerization is closely related to the binding and hydrolysis of GTP. ZipA contains a short amino-terminal region integrated in the membrane and connected to the globular carboxy-terminal domain (through which it interacts with the FtsZ central hub) by a flexible, unstructured linker region. FtsA is an actin-like protein, with a short amphipathic helix that mediates its association to the membrane. The position of the ring at midcell is highly regulated by several negative control systems that inhibit its incorrect formation. One of them involves the self-oscillating MinCDE protein complex, which oscillates from pole to pole, blocking polymerization of FtsZ at both poles.As the assembly of the proto-ring complex in vivo takes place at the inner bacterial membrane, a considerable effort has been (and is being) made to study the assembly properties of FtsZ and its interaction with companion proteins in reconstructions of the proto-ring structured as biomimetic membrane systems. Among them, supported lipid bilayers (SLBs) are well suited to investigate the reactivity (i.e. dynamic interactions) and the membrane structural organization of division proteins by surface sensitive imaging techniques, under biochemically controlled and well-defined experimental conditions...
Bacterial cell division in E. coli is mediated by a multiprotein machine whose elements interact dynamically at midcell to form the division ring, a structure that drives cytokinesis forming part of the divisome. The first macromolecular assembly of the divisome is the proto-ring, comprising three proteins – FtsZ, FtsA, and ZipA – that associate at the cytoplasmic membrane forming the scaffold structure into which the rest of the essential division proteins are incorporated. FtsZ is a GTPase and its polymerization is closely related to the binding and hydrolysis of GTP. ZipA contains a short amino-terminal region integrated in the membrane and connected to the globular carboxy-terminal domain (through which it interacts with the FtsZ central hub) by a flexible, unstructured linker region. FtsA is an actin-like protein, with a short amphipathic helix that mediates its association to the membrane. The position of the ring at midcell is highly regulated by several negative control systems that inhibit its incorrect formation. One of them involves the self-oscillating MinCDE protein complex, which oscillates from pole to pole, blocking polymerization of FtsZ at both poles.As the assembly of the proto-ring complex in vivo takes place at the inner bacterial membrane, a considerable effort has been (and is being) made to study the assembly properties of FtsZ and its interaction with companion proteins in reconstructions of the proto-ring structured as biomimetic membrane systems. Among them, supported lipid bilayers (SLBs) are well suited to investigate the reactivity (i.e. dynamic interactions) and the membrane structural organization of division proteins by surface sensitive imaging techniques, under biochemically controlled and well-defined experimental conditions...
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Tesis de la Universidad Complutense de Madrid, Facultad de Ciencias Químicas, Departamento de Bioquímica y Biología Molecular, leída el 02-07-2018