Molecular basis for the distinct divalent cation requirement in the uridylylation of the signal transduction proteins GlnJ and GlnB from Rhodospirillum rubrum
Autor
Teixeira, Pedro Filipe
Nordlund, Stefan
Domínguez-Martín, María A.
Editor
BioMed CentralFecha
2012Materia
PII proteinsPost-translational modification
Uridylyltransferase
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Background: PII proteins have a fundamental role in the control of nitrogen metabolism in bacteria, through
interactions with different PII targets, controlled by metabolite binding and post-translational modification,
uridylylation in most organisms. In the photosynthetic bacterium Rhodospirillum rubrum, the PII proteins GlnB and
GlnJ were shown, in spite of their high degree of similarity, to have different requirements for post-translational
uridylylation, with respect to the divalent cations, Mg2+ and Mn2+.
Results: Given the importance of uridylylation in the functional interactions of PII proteins, we have hypothesized
that the difference in the divalent cation requirement for the uridylylation is related to efficient binding of Mg/Mn-ATP to
the PII proteins. We concluded that the amino acids at positions 42 and 85 in GlnJ and GlnB (in the vicinity of the ATP
binding site) influence the divalent cation requirement for uridylylation catalyzed by GlnD.
Conclusions: Efficient binding of Mg/Mn-ATP to the PII proteins is required for uridylylation by GlnD. Our results show
that by simply exchanging two amino acid residues, we could modulate the divalent cation requirement in the
uridylylation of GlnJ and GlnB.
Considering that post-translational uridylylation of PII proteins modulates their signaling properties, a different
requirement for divalent cations in the modification of GlnB and GlnJ adds an extra regulatory layer to the already
intricate control of PII function