Uridylylation of the P(II) protein in the photosynthetic bacterium Rhodospirillum rubrum.

AUTOR(ES)

Johansson, M

RESUMO

The regulatory protein P(II) has been studied in great detail in enteric bacteria; however, its function in photosynthetic bacteria has not been clearly established. As a number of these bacteria have been shown to regulate nitrogenase activity by a metabolic control system, it is of special interest to establish the role of P(II) in these diazotrophs. In this study, we show that P(II) in Rhodospirillum rubrum is modified in response to the N status in the cell and that addition of ammonium or glutamine leads to demodification. We also provide evidence that P(II) is uridylylated. In addition, we show that not only these compounds but also NAD+ promotes demodification of P(II), which is of particular interest as this pyridine nucleotide has been shown to act as a switch-off effector of nitrogenase. Demodification of P(II) by ammonium or NAD+ did not occur in cultures treated with an inhibitor of glutamine synthetase (methionine sulfoximine), whereas treatment with the glutamate synthase inhibitor 6-diazo-5-oxo-norleucine led to total demodification of P(II) without any other addition. The results indicate that P(II) probably is not directly involved in darkness switch-off of nitrogenase but that a role in ammonium switch-off cannot be excluded.

Documentos Relacionados

• Phototaxis and membrane potential in the photosynthetic bacterium Rhodospirillum rubrum.
• Efficiency of light-driven metabolite transport in the photosynthetic bacterium Rhodospirillum rubrum.
• Purification and characterization of the alternative nitrogenase from the photosynthetic bacterium Rhodospirillum rubrum.
• Evidence for two light-driven reactions in the purple photosynthetic bacterium, Rhodospirillum rubrum.
• The Effect of Light on the Oxygen Metabolism of the Photosynthetic Bacterium, Rhodospirillum rubrum. 12