Energy status and cytochromes in isolated endophytic vesicle clusters of red alder root nodules

1983 ◽  
Vol 13 (5) ◽  
pp. 921-928 ◽  
Author(s):  
Te May Ching ◽  
Philip A. Monaco ◽  
Kim K. Ching
Keyword(s):  
Oxygen Uptake ◽  
Nitrogenase Activity ◽  
Root Nodules ◽  
Energy Charge ◽  
Energy Status ◽  
Red Alder ◽  
Cellular Energy ◽  
Adenylate Pool ◽  
39 B 22 ◽  
Cytochrome P 450

Anaerobically isolated endophytic vesicle clusters from root nodules of Alnusrubra Bong. were low in cellular energy charge (0.4 to 0.5), total adenylate pool (0.4 to 0.9 nmolùmg protein−1), and nitrogenase activity (0.1 to 0.3 nmolùmg protein−1). Upon addition of substrate (glucose, sucrose, isocitrate + isocitrate dehydrogenase + NADP), energy charge decreased by 2 to 20%, total adenylate pool increased by 3- to 11-fold, and nitrogenase activity increased by 50 to 500%. Only ATP and dithionite supported substantial nitrogenase activity and greatly elevated energy status. Treating vesicle clusters with macerase and cellulase to remove the host capsule facilitated substrate and oxygen uptake, resulting in a 240% increase in total adenylate pool, a 60% increase in energy charge, and a 730% increase in nitrogenase activity. Isolated vesicle clusters contained about 320 nmol cytochromes•g protein−1, with an average molar distribution of 17% cytochrome a-a3, 39% b, 22% c, and 21% o. No cytochrome P 450 was observed in vesicle clusters. The presence of cytochromes a-a3 and o may be a mechanism of oxygen tolerance whereby the nitrogenase in Frankia spp. can operate in an environment without the protection of leghaemoglobin.

The role of oxygen diffusion from the shoots and nodule roots in nitrogen fixation by root nodules of Myrica gale

1978 ◽  
Vol 56 (11) ◽  
pp. 1365-1371 ◽  
Author(s):  
John Tjepkema
Keyword(s):  
Nitrogen Fixation ◽  
Oxygen Uptake ◽  
Aqueous Phase ◽  
Acetylene Reduction ◽  
Nitrogenase Activity ◽  
Root Nodules ◽  
Myrica Gale ◽  
Before And After ◽  
Whole Plants

Nitrogenase activity (acetylene reduction) and oxygen uptake by root nodules of Myrica gale L. were measured before and after removal of nodule roots. There was no significant effect of nodule root removal when respiration was measured in the gas phase (0.05–0.2 atm pO2 (1 atm = 101.325 kPa)) or acetylene reduction in a stirred aqueous phase at 0.2 atm pO2. However, when acetylene reduction was measured in 0.05 atm pO2 in an unstirred aqueous phase, there was a 66 to 76% reduction in activity. These results indicate that nodule roots are important for oxygen uptake when the nodules are present in an aqueous phase at low pO2, which is probably the normal environmental conditions for many of the nodules. Other measurements showed that diffusion of oxygen from the shoot to the root nodules is not important for nitrogen fixation. These measurements were done on whole plants with the shoots in air (0.20 atm pO2) and the roots in water at the desired pO2 value. With 0.0 atmpO2 in the root environment, the rate of acetylene reduction was only 4% of the rate at 0.2 atmpO2. Thus, only small amounts of oxygen are transported from the shoot to the nodules.

scholarly journals Leucine or carbohydrate supplementation reduces AMPK and eEF2 phosphorylation and extends postprandial muscle protein synthesis in rats

2011 ◽  
Vol 301 (6) ◽  
pp. E1236-E1242 ◽  
Author(s):  
Gabriel J. Wilson ◽  
Donald K. Layman ◽  
Christopher J. Moulton ◽  
Layne E. Norton ◽  
Tracy G. Anthony ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Test Meal ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Adenosine Monophosphate ◽  
Energy Status ◽  
Sprague Dawley ◽  
Translation Elongation ◽  
Cellular Energy ◽  
Mtorc1 Signaling

Muscle protein synthesis (MPS) increases after consumption of a protein-containing meal but returns to baseline values within 3 h despite continued elevations of plasma amino acids and mammalian target of rapamycin (mTORC1) signaling. This study evaluated the potential for supplemental leucine (Leu), carbohydrates (CHO), or both to prolong elevated MPS after a meal. Male Sprague-Dawley rats (∼270 g) trained to consume three meals daily were food deprived for 12 h, and then blood and gastrocnemius muscle were collected 0, 90, or 180 min after a standard 4-g test meal (20% whey protein). At 135 min postmeal, rats were orally administered 2.63 g of CHO, 270 mg of Leu, both, or water (sham control). Following test meal consumption, MPS peaked at 90 min and then returned to basal ( time 0) rates at 180 min, although ribosomal protein S6 kinase and eIF4E-binding protein-1 phosphorylation remained elevated. In contrast, rats administered Leu and/or CHO supplements at 135 min postmeal maintained peak MPS through 180 min. MPS was inversely associated with the phosphorylation states of translation elongation factor 2, the “cellular energy sensor” adenosine monophosphate-activated protein kinase-α (AMPKα) and its substrate acetyl-CoA carboxylase, and increases in the ratio of AMP/ATP. We conclude that the incongruity between MPS and mTORC1 at 180 min reflects a block in translation elongation due to reduced cellular energy. Administering Leu or CHO supplements ∼2 h after a meal maintains cellular energy status and extends the postprandial duration of MPS.

scholarly journals Paraburkholderia phymatum Homocitrate Synthase NifV Plays a Key Role for Nitrogenase Activity during Symbiosis with Papilionoids and in Free-Living Growth Conditions

Cells ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 952
Author(s):  
Paula Bellés-Sancho ◽  
Martina Lardi ◽  
Yilei Liu ◽  
Sebastian Hug ◽  
Marta Adriana Pinto-Carbó ◽  
...  
Keyword(s):  
Nitrogenase Activity ◽  
Root Nodules ◽  
Growth Conditions ◽  
Lysine Biosynthesis ◽  
Metabolome Analysis ◽  
Plant Host ◽  
Free Living ◽  
Bacterial Enzyme ◽  
Homocitrate Synthase ◽  
Iron Molybdenum Cofactor

Homocitrate is an essential component of the iron-molybdenum cofactor of nitrogenase, the bacterial enzyme that catalyzes the reduction of dinitrogen (N2) to ammonia. In nitrogen-fixing and nodulating alpha-rhizobia, homocitrate is usually provided to bacteroids in root nodules by their plant host. In contrast, non-nodulating free-living diazotrophs encode the homocitrate synthase (NifV) and reduce N2 in nitrogen-limiting free-living conditions. Paraburkholderia phymatum STM815 is a beta-rhizobial strain, which can enter symbiosis with a broad range of legumes, including papilionoids and mimosoids. In contrast to most alpha-rhizobia, which lack nifV, P. phymatum harbors a copy of nifV on its symbiotic plasmid. We show here that P. phymatum nifV is essential for nitrogenase activity both in root nodules of papilionoid plants and in free-living growth conditions. Notably, nifV was dispensable in nodules of Mimosa pudica despite the fact that the gene was highly expressed during symbiosis with all tested papilionoid and mimosoid plants. A metabolome analysis of papilionoid and mimosoid root nodules infected with the P. phymatum wild-type strain revealed that among the approximately 400 measured metabolites, homocitrate and other metabolites involved in lysine biosynthesis and degradation have accumulated in all plant nodules compared to uninfected roots, suggesting an important role of these metabolites during symbiosis.

Discovery of InsP6-kinases as InsP6-dephosphorylating enzymes provides a new mechanism of cytosolic InsP6 degradation driven by the cellular ATP/ADP ratio

2014 ◽  
Vol 462 (1) ◽  
pp. 173-184 ◽  
Author(s):  
Torsten Wundenberg ◽  
Nicole Grabinski ◽  
Hongying Lin ◽  
Georg W. Mayr
Keyword(s):  
Energy Charge ◽  
Inositol Hexakisphosphate ◽  
Cellular Energy

Inositol hexakisphosphate (InsP6) kinases are identified as InsP6 phosphorylating and dephosphorylating enzymes synthesizing either 5PP-InsP5 or Ins(2,3,4,5,6)P5. Their respective activity for InsP6 is dependent on the ATP/ADP ratio, thus acting as a cellular energy charge sensor.

Carbon Costs of Nitrogenase Activity in Legume Root Nodules determined using Acetylene and Oxygen

1983 ◽  
Vol 34 (8) ◽  
pp. 951-963 ◽  
Author(s):  
J. F. WITTY ◽  
F. R. MINCHIN ◽  
J. E. SHEEHY
Keyword(s):  
Nitrogenase Activity ◽  
Root Nodules ◽  
Carbon Costs

Seasonal pattern of energy use, respiration, and nitrogenase activity in root nodules of Myrica gale

1983 ◽  
Vol 61 (11) ◽  
pp. 2937-2942 ◽  
Author(s):  
Christa R. Schwintzer ◽  
John D. Tjepkema
Keyword(s):  
Energy Cost ◽  
Energy Use ◽  
Nitrogenase Activity ◽  
Root Nodules ◽  
Seasonal Pattern ◽  
Uptake Ratio ◽  
Experimental Conditions ◽  
Myrica Gale ◽  
Net Production ◽  
N Requirement

Annual CO2 evolution, H2 evolution, and C2H2 reduction were measured in root nodules from a vigorous Myrica gale stand in a Massachusetts peatland at 3-week intervals in 1980. Nodule activity was approximately the same under the experimental conditions (excised nodules reducing C2H2) as in nature (attached nodules reducing N2) and the CO2 evolution to O2 uptake ratio averaged 1.07. Nitrogenase activity was first detectable in late May, reached its maximum [Formula: see text] in mid-July, and disappeared in late October. The seasonal pattern of CO2 evolution was similar except that it continued at low rates when nitrogenase activity was absent. Hydrogen evolution was barely detectable. The energy cost of nitrogen fixation, expressed as the molar CO2:C2H4 ratio, was relatively low [Formula: see text] throughout the period of substantial nitrogenase activity and had a mean annual value of 4.9. Annual N2 fixation was estimated to be 2.8 g N m−2year−1, contributing about 33% of the annual N requirement measured in 1979. Annual C use by nodules was about 21.0 g C m−2 year−1. If this C were available for additional net production, it would increase it by about 5.5%.

scholarly journals LKB1 and AMPK maintain epithelial cell polarity under energetic stress

2007 ◽  
Vol 177 (3) ◽  
pp. 387-392 ◽  
Author(s):  
Vincent Mirouse ◽  
Lance L. Swick ◽  
Nevzat Kazgan ◽  
Daniel St Johnston ◽  
Jay E. Brenman
Keyword(s):  
Tumor Suppressor ◽  
Cell Polarity ◽  
Growth Control ◽  
Epithelial Polarity ◽  
Energy Status ◽  
Ampk Signaling ◽  
Cellular Energy ◽  
Energetic Stress ◽  
Stress Dependent

LKB1 is mutated in both familial and spontaneous tumors, and acts as a master kinase that activates the PAR-1 polarity kinase and the adenosine 5′monophosphate–activated kinase (AMPK). This has led to the hypothesis that LKB1 acts as a tumor suppressor because it is required to maintain cell polarity and growth control through PAR-1 and AMPK, respectively. However, the genetic analysis of LKB1–AMPK signaling in vertebrates has been complicated by the existence of multiple redundant AMPK subunits. We describe the identification of mutations in the single Drosophila melanogaster AMPK catalytic subunit AMPKα. Surprisingly, ampkα mutant epithelial cells lose their polarity and overproliferate under energetic stress. LKB1 is required in vivo for AMPK activation, and lkb1 mutations cause similar energetic stress–dependent phenotypes to ampkα mutations. Furthermore, lkb1 phenotypes are rescued by a phosphomimetic version of AMPKα. Thus, LKB1 signals through AMPK to coordinate epithelial polarity and proliferation with cellular energy status, and this might underlie the tumor suppressor function of LKB1.

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