Expression of genes involved in nitrogen assimilation and the C/N balance sensing in Prochlorococcus sp. strain SS120.
The expression of five genes involved in nitrogen assimilation in cyanobacteria, namely glnA, glsF, icd, ntcA, and glnB, encoding three key enzymes from that pathway (glutamine synthetase, glutamate synthase, isocitrate dehydrogenase) and two regulatory proteins (NtcA and PII), was studied in this work. Their changes under different conditions were analyzed by quantitative real-time RT-PCR. Nutrient limitation induced clear modifications on the expression of most studied genes: lack of nitrogen provoked an initial increase, followed by a marked decrease; in the cases of phosphorus and iron starvation, a general, stronger expression decrease was observed, particularly striking in the case of iron. Darkness and addition of the photosynthethic inhibitors DCMU and DBMIB also had a strong effect on gene expression. Methionine sulfoximine and azaserine, inhibitors of glutamine synthetase and glutamate synthase, respectively, provoked a sharp increase in icd expression. These results, together with previous studies, suggest that 2-oxoglutarate could be the molecule utilized by Prochlorococcus to sense the C/N balance. Besides, our results confirm the different regulation of nitrogen assimilation in Prochlorococcus with regard to other cyanobacteria.
López-Lozano
Antonio
A
Departamento de Bioquímica y Biología Molecular, Universidad de Córdoba, 14071-Córdoba, Spain.
Gómez-Baena
Guadalupe
G
Muñoz-Marín
Maria del Carmen
Mdel C
Rangel
Oriol Alberto
OA
Diez
Jesús
J
García-Fernández
Jose Manuel
JM
D002244:Carbon / Q000378:metabolism*; D004579:Electron Transport / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial / Q000502:physiology; D007501:Iron / Q000378:metabolism; D000090463:Iron Deficiencies; D008027:Light; D053858:Metabolic Networks and Pathways / Q000235:genetics; D009584:Nitrogen / Q000378:metabolism*; D010758:Phosphorus / Q000172:deficiency / Q000378:metabolism; D010788:Photosynthesis / Q000235:genetics; D048929:Prochlorococcus / Q000235:genetics* / Q000378:metabolism; D053038:Quorum Sensing / Q000235:genetics; D013045:Species Specificity; D013217:Starvation / Q000235:genetics / Q000378:metabolism
D010758:Phosphorus; D002244:Carbon; D007501:Iron; D009584:Nitrogen