The nitrogen assimilation control (Nac) protein represses asnC and asnA transcription in Escherichia coli.
In this work, we show that the expression of the asnA and asnC genes is regulated by the availability of ammonium in the growth medium. Our results suggest that, under nitrogen-limiting growth conditions, the nitrogen assimilation control (Nac) protein is involved in the repression of the asnC gene, whose product is required to activate the transcription of asnA. We also show that asparagine negatively affects the expression of asnA, independently of the presence of Nac. These results allow us to conclude that asnA transcription is regulated by two different mechanisms that respond to different effectors: nitrogen and asparagine availability.
Poggio
Sebastian
S
Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ap. Postal 70-228, 04510, México, D.F., Mexico.
Domeinzain
Clelia
C
Osorio
Aurora
A
Camarena
Laura
L
D001216:Asparagine / Q000378:metabolism; D001217:Aspartate-Ammonia Ligase / Q000235:genetics*; D001426:Bacterial Proteins; D019733:Carbon-Nitrogen Ligases with Glutamine as Amide-N-Donor / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004794:Enzyme Repression; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D009584:Nitrogen / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism*
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C072712:NAC protein, bacteria; C489526:Nac protein, E coli; D014157:Transcription Factors; D001216:Asparagine; D001217:Aspartate-Ammonia Ligase; D019733:Carbon-Nitrogen Ligases with Glutamine as Amide-N-Donor; C019742:asparagine synthetase (glutamine-hydrolyzing); D009584:Nitrogen