A light-sensitive mechanism differently regulates transcription and transcript stability of omega3 fatty-acid desaturases (FAD3, FAD7 and FAD8) in soybean photosynthetic cell suspensions.
The omega3 fatty-acid desaturases: FAD7 and FAD8 (plastid) and FAD3 (reticular) are responsible for trienoic fatty-acid (TA) production in plants. The expression of these enzymes seemed to be regulated differently in response to light. Darkness leads to a decrease in total TA level. Under such conditions, FAD3 and FAD8 transcript levels were undetectable but increased after re-illumination concomitant with TA levels, indicating a transcriptional control. On the contrary, FAD7 transcript levels were similar to illuminated control cells, suggesting the presence of a post-transcriptional control mechanism. Furthermore, FAD7 mRNA stability increased dramatically in darkness. Analysis of FAD7 protein accumulation using specific antibodies revealed that FAD7 was very stable whatever the light or darkness conditions. These results indicate that FAD7 enzyme availability is not limiting for 18:3 production in darkness. Our data point to an additional post-translational regulatory mechanism that controls the activity of FAD7 in response to light.
Collados
Raquel
R
Department of Plant Nutrition, Estación Experimental de Aula Dei (CSIC), Apdo. 202, 50080 Zaragoza, Spain.
Andreu
Vanesa
V
Picorel
Rafael
R
Alfonso
Miguel
M
D000595:Amino Acid Sequence; D000906:Antibodies / Q000378:metabolism; D002478:Cells, Cultured; D003624:Darkness; D004795:Enzyme Stability; D044943:Fatty Acid Desaturases / Q000235:genetics / Q000378:metabolism; D015525:Fatty Acids, Omega-3 / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D008027:Light; D008969:Molecular Sequence Data; D010788:Photosynthesis / Q000502:physiology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D020871:RNA Stability; D016415:Sequence Alignment; D013025:Glycine max / Q000166:cytology / Q000201:enzymology*; D014158:Transcription, Genetic
D000906:Antibodies; D015525:Fatty Acids, Omega-3; D007527:Isoenzymes; D010940:Plant Proteins; D044943:Fatty Acid Desaturases