Mitochondria and chloroplasts as the original sites of melatonin synthesis: a hypothesis related to melatonin's primary function and evolution in eukaryotes
Top Cited Papers
Open Access
- 12 October 2012
- journal article
- review article
- Published by Wiley in Journal of Pineal Research
- Vol. 54 (2), 127-138
- https://doi.org/10.1111/jpi.12026
Abstract
Mitochondria and chloroplasts are major sources of free radical generation in living organisms. Because of this, these organelles require strong protection from free radicals and associated oxidative stress. Melatonin is a potent free radical scavenger and antioxidant. It meets the criteria as a mitochondrial and chloroplast antioxidant. Evidence has emerged to show that both mitochondria and chloroplasts may have the capacity to synthesize and metabolize melatonin. The activity of arylalkylamine N‐acetyltransferase (AANAT), the reported rate‐limiting enzyme in melatonin synthesis, has been identified in mitochondria, and high levels of melatonin have also been found in this organelle. From an evolutionary point of view, the precursor of mitochondria probably is the purple nonsulfur bacterium, particularly, Rhodospirillum rubrum, and chloroplasts are probably the descendents of cyanobacteria. These bacterial species were endosymbionts of host proto‐eukaryotes and gradually transformed into cellular organelles, that is, mitochondria and chloroplasts, respectively, thereby giving rise to eukaryotic cells. Of special importance, both purple nonsulfur bacteria (R. rubrum) and cyanobacteria synthesize melatonin. The enzyme activities required for melatonin synthesis have also been detected in these primitive species. It is our hypothesis that mitochondria and chloroplasts are the original sites of melatonin synthesis in the early stage of endosymbiotic organisms; this synthetic capacity was carried into host eukaryotes by the above‐mentioned bacteria. Moreover, their melatonin biosynthetic capacities have been preserved during evolution. In most, if not in all cells, mitochondria and chloroplasts may continue to be the primary sites of melatonin generation. Melatonin production in other cellular compartments may have derived from mitochondria and chloroplasts. On the basis of this hypothesis, it is also possible to explain why plants typically have higher melatonin levels than do animals. In plants, both chloroplasts and mitochondria likely synthesize melatonin, while animal cells contain only mitochondria. The high levels of melatonin produced by mitochondria and chloroplasts are used to protect these important cellular organelles against oxidative stress and preserve their physiological functions. The superior beneficial effects of melatonin in both mitochondria and chloroplasts have been frequently reported.Keywords
This publication has 107 references indexed in Scilit:
- Melatonin protects against neurobehavioral and mitochondrial deficits in a chronic mouse model of Parkinson's diseasePharmacology Biochemistry and Behavior, 2011
- Melatonin and steroid hormones activate intermembrane Cu,Zn-superoxide dismutase by means of mitochondrial cytochrome P450Free Radical Biology & Medicine, 2011
- Melatonin protects lung mitochondria from agingAGE, 2011
- Circadian regulation of molecular, dietary, and metabolic signaling mechanisms of human breast cancer growth by the nocturnal melatonin signal and the consequences of its disruption by light at nightJournal of Pineal Research, 2011
- Melatonin as an antioxidant and its semi-lunar rhythm in green macroalga Ulva sp.Journal of Experimental Botany, 2011
- The role of mitochondrial complex III in melatonin-induced ROS production in cultured mesangial cellsJournal of Pineal Research, 2010
- Removal of Melatonin Receptor Type 1 Induces Insulin Resistance in the MouseObesity, 2010
- Metabolism of melatonin by cytochrome P450s in rat liver mitochondria and microsomesJournal of Pineal Research, 2008
- Melatonin maintains mitochondrial membrane potential and attenuates activation of initiator (casp‐9) and effector caspases (casp‐3/casp‐7) and PARP in UVR‐exposed HaCaT keratinocytesJournal of Pineal Research, 2007
- On the origin of mitosing cellsJournal of Theoretical Biology, 1967