Photosynthetic control of nitrate metabolism in Phormidium uncinatum, a cyanobacterium

The impact of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) was studied on growth, Hill reaction, nitrate uptake, enzymes of nitrate utilization, and of oxidative pentose pathway by phototrophically growing Phormidium uncinatum and its DCMU-resistant (DCMU-R) mutant. The growth-inhibitory action of...

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Bibliographic Details
Published in:Current microbiology 1989-09, Vol.19 (3), p.183-188
Main Authors: Bagchi, S.N. (University of Bayreuth, Bayreuth, FRG), Palod, A, Chauhan, V.S
Format: Article
Language:English
Subjects:
6-PHOSPHOGLUCONATE DEHYDROGENASE
ADENOSINE TRIPHOSPHATE
ADENOSINTRIFOSFATO
Bacteriology
Biological and medical sciences
CYANOPHYTA
FOTOSINTESIS
Fundamental and applied biological sciences. Psychology
GLUCOSE-6-PHOSPHATE DEHYDROGENASE
METABOLISM
Metabolism. Enzymes
METABOLISME
METABOLISMO
Microbiology
NITRATE
NITRATES
NITRATOS
NITRITE
NITRITES
NITRITOS
OXIDOREDUCTASES
OXIDORREDUCTASAS
OXYDOREDUCTASE
Phormidium uncinatum
PHOTOSYNTHESE
PHOTOSYNTHESIS
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Summary:The impact of 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) was studied on growth, Hill reaction, nitrate uptake, enzymes of nitrate utilization, and of oxidative pentose pathway by phototrophically growing Phormidium uncinatum and its DCMU-resistant (DCMU-R) mutant. The growth-inhibitory action of DCMU was apparently the consequence of an inactivation of photosystem II (PS II) reaction and of reduction of nitrate utilization owing to an inhibition of nitrite reductase (NiR) activity. Mutation rendered both the processes insensitive to DCMU. Nitrate transport, nitrate reduction to nitrite, and ammonia assimilation of both the strains remained rather unaffected by DCMU. Photosynthetically inactive cells of the two strains exhibited higher activity levels of glucose-6-phosphate dehydrogenase (G6PDH) and 6-phosphogluconate dehydrogenase (6PGDH) than their phototrophic cultures.
ISSN:0343-8651
1432-0991
DOI:10.1007/BF01568939