Artículo
The heterocyst differentiation transcriptional regulator HetR of the filamentous cyanobactrium Anabaena forms tetramers and can be regulated by phosphorylation
Autor/es | Valladares Ruiz, Ana
Flores García, Enrique Herrero Moreno, Antonia |
Departamento | Universidad de Sevilla. Departamento de Bioquímica Vegetal y Biología Molecular |
Fecha de publicación | 2016 |
Fecha de depósito | 2018-01-03 |
Publicado en |
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Resumen | Many filamentous cyanobacteria respond to the external cue of nitrogen scarcity by the differentiation of heterocysts, cells specialized in the fixation of atmospheric nitrogen in oxic environments. Heterocysts follow a ... Many filamentous cyanobacteria respond to the external cue of nitrogen scarcity by the differentiation of heterocysts, cells specialized in the fixation of atmospheric nitrogen in oxic environments. Heterocysts follow a spatial pattern along the filament of two heterocysts separated by ca. 10–15 vegetative cells performing oxygenic photosynthesis. HetR is a transcriptional regulator that directs heterocyst differentiation. In the model strain Anabaena sp. PCC 7120, the HetR protein was observed in various oligomeric forms in vivo, including a tetramer that peaked with maximal hetR expression during differentiation. Tetramers were not detected in a hetR point mutant incapable of differentiation, but were conspicuous in an over-differentiating strain lacking the PatS inhibitor. In differentiated filaments the HetR tetramer was restricted to heterocysts, being undetectable in vegetative cells. HetR co-purified with RNA polymerase from Anabaena mainly as a tetramer. In vitro, purified recombinant HetR was distributed between monomers, dimers, trimers and tetramers, and it was phosphorylated when incubated with (γ-32P)ATP. Phosphorylation and PatS hampered the accumulation of HetR tetramers and impaired HetR binding to DNA. In summary, tetrameric HetR appears to represent a functionally relevant form of HetR, whose abundance in the Anabaena filament could be negatively regulated by phosphorylation and by PatS. |
Agencias financiadoras | Gobierno de España |
Identificador del proyecto | BFU2010-17980
BFU2013-44686-P |
Cita | Valladares Ruiz, A., Flores García, E. y Herrero Moreno, A. (2016). The heterocyst differentiation transcriptional regulator HetR of the filamentous cyanobactrium Anabaena forms tetramers and can be regulated by phosphorylation. Molecular Microbiology, 99 (4), 808-819. |
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