Properties of a nitrate reductase of Chlorella

Solomonson, L P; Vennesland, Birgit

doi:10.1016/0005-2728(72)90183-1

Cited by 98 publications

(30 citation statements)

References 34 publications

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“…The activity was also assayed in the presence of varying nitrate concentrations (0.05-2.0 mM). Added nitrate did not cause detectable inhibition of NADH-CR component of the enzyme as was observed by Solomonson and Vennesland (14).…”

supporting

confidence: 73%

Effect of Inorganic Orthophosphate on in Vitro Activity of NADH-Nitrate Reductase Isolated from 2-Row Barley Leaves

Oji

Ryoma²,

Wakiuchi³

et al. 1987

Plant Physiol.

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supporting

confidence: 73%

Effect of Inorganic Orthophosphate on in Vitro Activity of NADH-Nitrate Reductase Isolated from 2-Row Barley Leaves

Oji

Ryoma²,

Wakiuchi³

et al. 1987

Plant Physiol.

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“…Such an optimum is much lower than that found for green algae and higher plants (e.g. Solomonson & Vennesland 1972, Solomonson & Barber 1990, Loppes et al 1996. This difference has been discussed in an evolutionary context (Gao et al 2000).…”

Section: Temperature Effects On Nitrate Metabolismmentioning

confidence: 85%

Effects of temperature on growth rate, cell composition and nitrogen metabolism in the marine diatom Thalassiosira pseudonana (Bacillariophyceae)

Berges¹,

Varela²,

Harrison³

2002

Mar. Ecol. Prog. Ser.

141

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Although temperature effects on phytoplankton growth and photosynthesis can be clearly demonstrated in the laboratory, their relevance in the field is much harder to establish. Recently, however, it has been recognized that temperature has a significant influence on nitrogen uptake. In particular, temperate marine diatom species may be limited by their ability to acquire nitrate at temperatures above approximately 16°C. In order to explore this idea, we grew the diatom Thalassiosira pseudonana at 8, 17 and 25°C, and compared cell composition, and rates of growth (µ), 15 N incorporation, calculated nitrate incorporation (the product of µ and cell N content), and the activity of nitrate reductase (NR), a key enzyme involved in nitrate incorporation. Cell N content, protein and volume remained relatively constant across different temperatures, but cell C, chlorophyll a (chl a), and C:N ratio increased with increasing temperature, suggesting that C metabolism was affected more strongly than N metabolism. Classical temperature models suggested that growth and various indices of nitrate metabolism all responded to temperature, with Q 10 values of close to 2 over the whole temperature range. However, Q 10 values over the interval from 8 to 17°C were higher than 2 and much lower than 2 between 17 and 25°C. Limitations to the Q 10 concept are considered. Temperature effects on different measures of nitrate metabolism were very similar, supporting the hypothesis that the effects of temperature on diatom nitrate metabolism are mediated at the level of NR activity. Recent biochemical data for NR also supports this idea.

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“…Ostensibly, NR reduces NO 3 Ϫ to NO 2 Ϫ , using electrons derived from NAD(P)H (Taiz and Zeiger 1991). In higher plants and algae, both soluble NR (Solomonson and Vennesland 1972;Redinbaugh and Campbell 1983;Castignetti and Smarrelli 1984) and plasmalemma bound NR (Jones et al 1987;Jones and Morel 1988;Corzo et al 1991;Stöhr et al 1993), can catalyze the reduction of Fe bound to organic complexes. In heterotrophic bacteria, mutants lacking NR are deficient in the Fe reductase pathway (Ottow 1968(Ottow , 1970.…”

Section: Reduction Of Fe(iii) Bound To Dtpa and Dfb-mentioning

confidence: 99%

Nitrate regulation of Fe reduction and transport by Fe‐limited Thalassiosira oceanica

Maldonado

Price

2000

Limnology & Oceanography

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Under Fe-limiting conditions, nitrate (NO 3 Ϫ )-grown marine diatoms have higher intracellular Fe requirements, but divide as fast or faster than ammonium (NH 4 ϩ )-grown cells by maintaining faster steady-state Fe uptake rates. Here we report that Thalassiosira oceanica, clone 1003, possesses an Fe reductase that reduces Fe(III) bound to a variety of organic ligands, including the siderophore desferrioxamine B (DFB), a high affinity, Fe(III)-specific ligand. Reduction is mediated extracellularly and is induced by Fe deficiency. Cellular rates of Fe(III) reduction are significantly faster in NO 3 Ϫ -than in NH 4 ϩ -grown cultures suggesting a link with N metabolism. At subsaturating Fe concentrations, short-and long-term Fe uptake rates are also significantly faster in NO 3 Ϫ -than in NH 4 ϩ -grown cells. The results suggest that when Fe is limiting, faster rates of reduction of organically bound Fe(III) by phytoplankton promote faster rates of Fe transport and growth. The implications of these findings could be significant for understanding phytoplankton Fe nutrition in oceanic waters where organic complexation dominates the speciation of Fe. We hypothesize that the reductive Fe transport pathway may enable phytoplankton to directly utilize Fe bound to strong organic ligands in the sea.Iron plays a catalytic role in many biochemical reactions as a cofactor of enzymes and proteins involved in chlorophyll synthesis, detoxification of reactive oxygen species, respiratory and photosynthetic electron transport, and N assimilation. Changes in the activity of these reactions or their replacement by functionally equivalent Fe-deficient pathways can greatly influence cellular Fe requirements of organisms. Because the NO 3 Ϫ assimilatory pathway is highly Fe dependent, utilization of NO 3 Ϫ by marine centric diatoms (Thalassiosira spp.) imparts a higher metabolic demand for Fe than the use of NH 4 ϩ . The demand for Fe is such that the Fe quotas (Fe : C) of NO 3 Ϫ -grown cells are 1.8 times higher than those of phytoplankton using NH 4 ϩ (Maldonado and Price 1996). Despite the higher Fe requirement for NO 3 Ϫ assimilation, under moderately Fe-limiting conditions (ca. 0.7-0.85 / max ), growth rates of NO 3 Ϫ -amended cultures are not slower than those of NH 4 ϩ -amended ones (Maldonado and Price 1996). Nitrate-grown cells apparently compensate for their extra Fe requirement by sustaining faster steadystate Fe uptake rates (Maldonado and Price 1996). The 1 To whom correspondence should be addressed. Present address: 5741 Libby Hall, School of Marine Sciences, University of Maine, Orono, ME 04469 (maria.maldonado@maine.edu). AcknowledgmentsWe thank P. Tortell, C. Payne, Z. Chase, and J. Granger for valuable discussions, suggestions, and comments on earlier versions of this manuscript. The help of E. Maldonado-Pareja and C. Molony in the lab was particularly appreciated. We are grateful to M. Soon (U. of British Columbia) for CHN analysis, to W. King (Colby College, ME) for guidance with the Fe(II) chemiluminescence ...

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Properties of a nitrate reductase of Chlorella

Cited by 98 publications

References 34 publications

Effect of Inorganic Orthophosphate on in Vitro Activity of NADH-Nitrate Reductase Isolated from 2-Row Barley Leaves

Effect of Inorganic Orthophosphate on in Vitro Activity of NADH-Nitrate Reductase Isolated from 2-Row Barley Leaves

Effects of temperature on growth rate, cell composition and nitrogen metabolism in the marine diatom Thalassiosira pseudonana (Bacillariophyceae)

Nitrate regulation of Fe reduction and transport by Fe‐limited Thalassiosira oceanica

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