Function of the chloroplastic malate valve for respiration during photosynthesis

1996 ◽  
Vol 24 (3) ◽  
pp. 761-766 ◽  
Author(s):  
S. Krömer ◽  
R. Scheibe
Keyword(s):  
Malate Valve

scholarly journals Multiple strategies to prevent oxidative stress in Arabidopsis plants lacking the malate valve enzyme NADP-malate dehydrogenase

2011 ◽  
Vol 63 (3) ◽  
pp. 1445-1459 ◽  
Author(s):  
Inga Hebbelmann ◽  
Jennifer Selinski ◽  
Corinna Wehmeyer ◽  
Tatjana Goss ◽  
Ingo Voss ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Malate Dehydrogenase ◽  
Multiple Strategies ◽  
Malate Valve

scholarly journals Putative role of the malate valve enzyme NADP–malate dehydrogenase in H 2 O 2 signalling in Arabidopsis

2014 ◽  
Vol 369 (1640) ◽  
pp. 20130228 ◽  
Author(s):  
Eiri Heyno ◽  
Gilles Innocenti ◽  
Stéphane D. Lemaire ◽  
Emmanuelle Issakidis-Bourguet ◽  
Anja Krieger-Liszkay
Keyword(s):  
Malate Dehydrogenase ◽  
Catalase Activity ◽  
Redox State ◽  
Electron Flow ◽  
Light Stress ◽  
Reversible Inactivation ◽  
Photosynthetic Organisms ◽  
Cell Compartments ◽  
Malate Valve

In photosynthetic organisms, sudden changes in light intensity perturb the photosynthetic electron flow and lead to an increased production of reactive oxygen species. At the same time, thioredoxins can sense the redox state of the chloroplast. According to our hypothesis, thioredoxins and related thiol reactive molecules downregulate the activity of H 2 O 2 -detoxifying enzymes, and thereby allow a transient oxidative burst that triggers the expression of H 2 O 2 responsive genes. It has been shown recently that upon light stress, catalase activity was reversibly inhibited in Chlamydomonas reinhardtii in correlation with a transient increase in the level of H 2 O 2 . Here, it is shown that Arabidopsis thaliana mutants lacking the NADP–malate dehydrogenase have lost the reversible inactivation of catalase activity and the increase in H 2 O 2 levels when exposed to high light. The mutants were slightly affected in growth and accumulated higher levels of NADPH in the chloroplast than the wild-type. We propose that the malate valve plays an essential role in the regulation of catalase activity and the accumulation of a H 2 O 2 signal by transmitting the redox state of the chloroplast to other cell compartments.

scholarly journals The chloroplastic 2-oxoglutarate/malate transporter has dual function as the malate valve and in carbon/nitrogen metabolism

2010 ◽  
Vol 65 (1) ◽  
pp. 15-26 ◽  
Author(s):  
Hiromu Kinoshita ◽  
Junko Nagasaki ◽  
Nanako Yoshikawa ◽  
Aya Yamamoto ◽  
Shizuka Takito ◽  
...  
Keyword(s):  
Nitrogen Metabolism ◽  
Dual Function ◽  
Malate Valve ◽  
Malate Transporter

scholarly journals The Complementary Roles of Chloroplast Cyclic Electron Transport and Mitochondrial Alternative Oxidase to Ensure Photosynthetic Performance

2021 ◽  
Vol 12 ◽  
Author(s):  
Avesh Chadee ◽  
Nicole A. Alber ◽  
Keshav Dahal ◽  
Greg C. Vanlerberghe
Keyword(s):  
Electron Transport ◽  
Alternative Oxidase ◽  
Carbon Fixation ◽  
Electron Flux ◽  
Adenine Nucleotide ◽  
Cyclic Electron Transport ◽  
Transport Pathways ◽  
Production Ratio ◽  
Malate Valve ◽  
Adenine Nucleotide Pool

Chloroplasts use light energy and a linear electron transport (LET) pathway for the coupled generation of NADPH and ATP. It is widely accepted that the production ratio of ATP to NADPH is usually less than required to fulfill the energetic needs of the chloroplast. Left uncorrected, this would quickly result in an over-reduction of the stromal pyridine nucleotide pool (i.e., high NADPH/NADP+ ratio) and under-energization of the stromal adenine nucleotide pool (i.e., low ATP/ADP ratio). These imbalances could cause metabolic bottlenecks, as well as increased generation of damaging reactive oxygen species. Chloroplast cyclic electron transport (CET) and the chloroplast malate valve could each act to prevent stromal over-reduction, albeit in distinct ways. CET avoids the NADPH production associated with LET, while the malate valve consumes the NADPH associated with LET. CET could operate by one of two different pathways, depending upon the chloroplast ATP demand. The NADH dehydrogenase-like pathway yields a higher ATP return per electron flux than the pathway involving PROTON GRADIENT REGULATION5 (PGR5) and PGR5-LIKE PHOTOSYNTHETIC PHENOTYPE1 (PGRL1). Similarly, the malate valve could couple with one of two different mitochondrial electron transport pathways, depending upon the cytosolic ATP demand. The cytochrome pathway yields a higher ATP return per electron flux than the alternative oxidase (AOX) pathway. In both Arabidopsis thaliana and Chlamydomonas reinhardtii, PGR5/PGRL1 pathway mutants have increased amounts of AOX, suggesting complementary roles for these two lesser-ATP yielding mechanisms of preventing stromal over-reduction. These two pathways may become most relevant under environmental stress conditions that lower the ATP demands for carbon fixation and carbohydrate export.

Flux Control of the Malate Valve in Leaf Cells

1998 ◽  
Vol 349 (2) ◽  
pp. 290-298 ◽  
Author(s):  
Leonid E. Fridlyand ◽  
Jan E. Backhausen ◽  
Renate Scheibe
Keyword(s):  
Flux Control ◽  
Malate Valve
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