Abstract
The penultimate enzyme in melatonin synthesis is serotonin N-acetyltransferase (SNAT), which exists as a single copy in mammals and plants. Our recent studies of the Arabidopsis snat-knockout mutant and SNAT RNAi rice (Oryza sativa) plants predicted the presence of at least one other SNAT isogene in plants; that is, the snat-knockout mutant of Arabidopsis and the SNAT RNAi rice plants still produced melatonin, even in the absence or the suppression of SNAT expression. Here, we report a molecular cloning of an SNAT isogene (OsSNAT2) from rice. The mature amino acid sequences of SNAT proteins indicated that OsSNAT2 and OsSNAT1 proteins had 39% identity values and 60% similarity. The Km and Vmax values of the purified recombinant OsSNAT2 were 371 μm and 4700 pmol/min/mg protein, respectively; the enzyme's optimal activity temperature was 45°C. Confocal microscopy showed that the OsSNAT2 protein was localized to both the cytoplasm and chloroplasts. The in vitro enzyme activity of OsSNAT2 was severely inhibited by melatonin, but the activities of sheep SNAT (OaSNAT) and rice OsSNAT1 proteins were not. The enzyme activity of OsSNAT2 was threefold higher than that of OsSNAT1, but 232-fold lower than that of OaSNAT. The OsSNAT1 and OsSNAT2 transcripts were similarly suppressed in rice leaves during the melatonin induction after cadmium treatment. Phylogenetic analyses indicated that OsSNAT1 and OsSNAT2 are distantly related, suggesting that they evolved independently from Cyanobacteria prior to the endosymbiosis event.
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Claims 14
Claim · model-written summary
OsSNAT2 was cloned from rice.
- Taxon
- rice
Oryza sativae0 - Gene
- OsSNAT2e0
- Outcome
- molecular cloninge0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“we report a molecular cloning of an SNAT isogene (OsSNAT2) from rice”
Claim · model-written summary
OsSNAT2 and OsSNAT1 proteins had 39% sequence identity.
- Taxon
- riceOryza sativae1
- Gene
- OsSNAT2 and OsSNAT1e0
- Outcome
- identity valuese0
- Value
- 39%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“OsSNAT2 and OsSNAT1 proteins had 39% identity values and 60% similarity”
e1“from rice”
Claim · model-written summary
OsSNAT2 and OsSNAT1 proteins had 60% sequence similarity.
- Taxon
- riceOryza sativae1
- Gene
- OsSNAT2 and OsSNAT1e0
- Outcome
- similaritye0
- Value
- 60%e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“OsSNAT2 and OsSNAT1 proteins had 39% identity values and 60% similarity”
e1“from rice”
Claim · model-written summary
Purified recombinant OsSNAT2 had a Km of 371 μm.
- Taxon
- riceOryza sativae1
- Gene
- OsSNAT2e0
- Outcome
- Kme0
- Value
- 371 μme0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The Km and Vmax values of the purified recombinant OsSNAT2 were 371 μm and 4700 pmol/min/mg protein, respectively”
e1“from rice”
Claim · model-written summary
Purified recombinant OsSNAT2 had a Vmax of 4700 pmol/min/mg protein.
- Taxon
- riceOryza sativae1
- Gene
- OsSNAT2e0
- Outcome
- Vmaxe0
- Value
- 4700 pmol/min/mg proteine0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The Km and Vmax values of the purified recombinant OsSNAT2 were 371 μm and 4700 pmol/min/mg protein, respectively”
e1“from rice”
Claim · model-written summary
OsSNAT2 enzyme activity was optimal at 45°C.
- Taxon
- riceOryza sativae2
- Gene
- OsSNAT2e1
- Outcome
- optimal activity temperaturee0
- Value
- 45°Ce0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the enzyme's optimal activity temperature was 45°C”
e1“purified recombinant OsSNAT2”
e2“from rice”
Claim · model-written summary
OsSNAT2 localized to cytoplasm and chloroplasts.
- Taxon
- riceOryza sativae1
- Gene
- OsSNAT2e0
- Outcome
- localized to both the cytoplasm and chloroplastse0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“OsSNAT2 protein was localized to both the cytoplasm and chloroplasts”
e1“from rice”
Claim · model-written summary
Melatonin severely inhibited OsSNAT2 in vitro activity.
- Taxon
- riceOryza sativae1
- Treatment
- melatonine0
- Gene
- OsSNAT2e0
- Outcome
- in vitro enzyme activitye0
- Direction
- inhibitede0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The in vitro enzyme activity of OsSNAT2 was severely inhibited by melatonin”
e1“from rice”
Claim · model-written summary
Melatonin did not inhibit rice OsSNAT1 activity.
- Taxon
- riceOryza sativae0
- Treatment
- melatonine1
- Gene
- OsSNAT1e0
- Outcome
- activities of sheep SNAT (OaSNAT) and rice OsSNAT1 proteinse0
- Direction
- were note0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“the activities of sheep SNAT (OaSNAT) and rice OsSNAT1 proteins were not”
e1“was severely inhibited by melatonin”
Claim · model-written summary
OsSNAT2 activity was threefold higher than OsSNAT1 activity.
- Taxon
- riceOryza sativae1
- Gene
- OsSNAT2e0
- Outcome
- enzyme activitye0
- Direction
- highere0
- Value
- threefolde0
- Comparator
- OsSNAT1e0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The enzyme activity of OsSNAT2 was threefold higher than that of OsSNAT1”
e1“from rice”
Claim · model-written summary
OsSNAT2 activity was 232-fold lower than sheep OaSNAT activity.
- Taxon
- riceOryza sativae2
- Gene
- OsSNAT2e1
- Outcome
- enzyme activitye1
- Direction
- lowere0
- Value
- 232-folde0
- Comparator
- OaSNATe0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“232-fold lower than that of OaSNAT”
e1“The enzyme activity of OsSNAT2”
e2“from rice”
Claim · model-written summary
Cadmium treatment and melatonin induction similarly suppressed OsSNAT1 and OsSNAT2 transcripts in rice leaves.
- Taxon
- riceOryza sativae0
- Organ / stage
- rice leavese0
- Treatment
- cadmium treatmente0
- Gene
- OsSNAT1 and OsSNAT2e0
- Outcome
- transcriptse0
- Direction
- suppressede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The OsSNAT1 and OsSNAT2 transcripts were similarly suppressed in rice leaves during the melatonin induction after cadmium treatment”
Claim · model-written summary
Phylogenetic analysis placed OsSNAT1 and OsSNAT2 as distantly related.
- Taxon
- riceOryza sativae1
- Gene
- OsSNAT1 and OsSNAT2e0
- Outcome
- distantly relatede0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Phylogenetic analyses indicated that OsSNAT1 and OsSNAT2 are distantly related”
e1“from rice”
Claim · model-written summary
The authors infer independent evolution of OsSNAT1 and OsSNAT2 from Cyanobacteria before endosymbiosis.
- Taxon
- riceOryza sativae2
- Gene
- OsSNAT1 and OsSNAT2e1
- Outcome
- evolved independently from Cyanobacteriae0
- Qualifier
- prior to the endosymbiosis evente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“suggesting that they evolved independently from Cyanobacteria prior to the endosymbiosis event”
e1“OsSNAT1 and OsSNAT2 are distantly related”
e2“from rice”
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