Tesis doctoral de Daniel Badia Martinez
Summary: this work describes the structural determination by x-ray crystallography of the phi29 bacteriophage protein p4, both bound and unbound to dna. protein p4 is essential for the bateriophage infective step, as it regulates its genes transcription, thus establishing two clearly differentiated transcriptional phases. This allows temporal separation of the phage protein synthesis: the proteins involved in phage dna replication are synthesized first and the structural proteins that form the bacteriophage particle later. There are three p4 functional binding sites in phi29 genome, which are located in a 219bp long intergenic region where the three most important promoters (a2b, a2c and a3) are located. in p4 absence, a2b and a2c promoters are active, while a3 promoter, due to not having a -35 box in its sequence, is unable of binding rna polymerase and remains inactive. when p4 protein is synthesized, it binds to its binding sites, thus producing different effects depending on the promoter. In a2b promoter, protein p4 binding site encloses the promoter -35 box, thus preventing rna polymerase binding and transcription consequently. In a2c promoter, although protein p4 enhances rna polymerase binding, the enzyme is unable to perform its function because the complex is overstabilized and so rna polymerase cannot escape from the promoter. In a3 promotor, protein p4 recruits rna polymerase, thus allowing transcription initiation. protein p4 was crystallized in two different space groups, c2221 in presence of a platinum compost and p212121 in its absence. Phases were obtained by mad, collecting 3 data sets at different wavelengths to have differences in the symmetric reflections intensities due to the effect as an anomal dispersor of the platinium. The protein model was refined up to 3 í¥ in the c2221 space group, and this model was used to perform a molecular replacement in the p212121 crystal. In this former space group, the mod
Datos académicos de la tesis doctoral «Caracteritzacio estructural de la proteÁ¯na p4, un regulador de la transcripcio en el bacteriofag phi29«
- Título de la tesis: Caracteritzacio estructural de la proteÁ¯na p4, un regulador de la transcripcio en el bacteriofag phi29
- Autor: Daniel Badia Martinez
- Universidad: Politécnica de catalunya
- Fecha de lectura de la tesis: 22/07/2005
Dirección y tribunal
- Director de la tesis
- Miquel Coll
- Tribunal
- Presidente del tribunal: margarita Salas falgueras
- ignacio Fita rodriguez (vocal)
- Juan Aymami bofarull (vocal)
- Manuel Espinosa padrón (vocal)