CaMV 35 S Promoter

cropped-picture1.jpgCaMV 35 S Promoter

The CaMV 35 S promoter, most commonly used for constitutive expression of foreign proteins in plants is a sequence of 528 base pairs. In the viral genome, the nucleotide sequence of CaMV P6 protein precedes the 35 S promoter sequence. However, the third part of P6 gene sequence overlaps the promoter sequence.

  1. The 35 S promoter sequence used in transgenic plants does not have ATG at 5’ end nor a translation start site which excludes the possibility of plant cells making the third domain of P6 protein.
  2. Expression of P6 sequence needs a plant active promoter of its own.
  3. No scientific literature has been reported on any allergenic properties of CaMV and no similarities have been shown to know allergens.
  4. Most likely the P6 protein is not an allergen as concluded by Podevin 2012.
  5. P35S variants do not contain ORFs that encode for proteins that have allergenic or toxic properties.
  6. These sequences/proteins (like P6) are ubiquitous in nature and have been part of mammalian diets even before human beings evolved.
  7. We find plant viral genomes in most crops and plant species.  This is because plants and viruses have been exchanging genes since millions of years.
  8. The cauliflower, broccoli, knoll-khol and cabbage we buy in local markets carry CaMV virus due to natural infestation and conatain P6 protein.
  9. There is a history of safe use of CaMV by humans both in rDNA form and in natural forms.
  10. Fifty four commercialized GM events (carrying CaMV 35 S Promoter) have passed biosafety tests.

Directions:

  1. The possibility of transgenic plants expressing P6 protein (third fragment)  can easily be checked by using monoclonal antibodies to P6 protein.
  2. The quantitative analysis to measure the amount of third fragment of P6 can be carried out.
  3. Even if the third domain/fragment of P6 is produced in plant cells, it needs to be checked if it is functional.
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Author: polumetla

I am a plant molecular biologist and biotechnologist. I worked as Director of National Research Centre on Plant Biotechnology, New Delhi, India; Director, Institute of Biotechnology, Acharya N.G. Ranga Agricultural University, Hyderabad, India; and Director, ICAR-Indian Institute of Rice Research, Hyderabad, India.

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