Estudio de la morfogénesis y empaquetamiento del DNA en el bacteriófago T7 mediante criomicroscopia electrónica y procesamiento de imagen
Author
Agirrezabala, XabierEntity
UAM. Departamento de Biología MolecularDate
2005-11-07Subjects
Microscopía electrónica - Tesis doctorales; Bacteriófagos - Genética - Tesis doctorales; ADN - Tesis doctorales; Biología y Biomedicina / BiologíaNote
Tesis Doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Biología Molecular. Fecha de lectura: 07-11-2005Abstract
The double-stranded (ds) DNA bacteriophages are good model systems to understand
basic biological processes such as the macromolecular interactions that take place
during the virus assembly and maturation, or the behaviour of molecular motors that
function during the DNA packaging process.
Using cryoeiechon microscopy and single-particle methodology, the structures of two
phage T7 assemblies produced during its morphogenetic process, the DNA-free prohead
and the mature virion have been determined. The first structure reveals a complex
assembly in the interior of the capsid, which involves the scaffolding, and the core
complex, which plays an important role in DNA packaging and it is located in one of
the phage vertex. The reconstruction of the mature virion reveals important changes in
the shell, now much larger and thinner, the disappearance of the scaffolding structure,
and important movements and rearrangements of the core complex, which now
protrudes the shell and interacts with the tail. Some of these changes must originate by
the pressure exerted by the DNA in the interior of the head.
Additionally, the three-dimensional structure of the connector of bacteriophage T7 has
been also obtained at 8 A resolution from purified connectors obtained afier overexpression
of the cloned gene. The comparison between the connectors of $29 and T7
shows interesting analogies and differences. The narrower part of the channel of the T7
connector is almost identical to the narrow domain in $29 (the region responsible for the
interaction with the DNA), while the rest of the volume, although exhibiting an overall
similarity, shows consistent differences compatible with the different mass of both
connector proteins. Docking of the atomic structure of the $29 connector into the T7
connector volume reconstructed by cryo-electron microscopy allows to propose the
presence of a ct 1 !3 module building an important region of the channel that might be
common to other DNA translocating connectors.
Files in this item
Google Scholar:Agirrezabala, Xabier
This item appears in the following Collection(s)
Related items
Showing items related by title, author, creator and subject.