PLANT PROMOTERS
Guided By :
Mrs. Anupama
What are Promoters?
• It is a region of DNA that initiates
transcription of a particular gene.
• They are located near the transcription sites
of genes, on the same strand and upstream
on the DNA (towards the 5’ region of the
sense strand)
• Promoters can be about 100 – 1000 base
pairs long.
FUNCTIONS OF PROMOTERS :
• To turn a gene into a protein product, at least two
general steps are required:
1. the gene is transcribed, spliced and processed to form
mRNA, and
2. the mRNA is translated into a polypeptide.
• Transcription is a controlled process. While multiple DNA
regions are involved, the promoter is the main
determinant for the initiation of transcription and
modulation of levels and timing of gene expression.
1.
2.
3.
• Promoter contains specific DNA sequences that
are recognized by proteins known as
‘transcription factors’.
• Transcription factors bind to promoter
sequences and recruit RNA polymerase.
• Transcription is initiated. The transcription
process only takes place in the downstream
direction, from 5’ (left) to 3’ (right)
Types of promoters
Promoters
used in
biotechnology
Constitutive
Tissue specific
promoters
Inducible
Synthetic
Constitutive Promoters
• These promoters have direct expression in virtually
all tissues and are largely, if not entirely, independent
of environmental and developmental factors.
• As their expression is normally not conditioned by
endogenous factors, they are usually active across
species and even across kingdoms.
• EXAMPLE : Plant Pathogen promoters (CaMV 35S
promoter)
Tissue /organ specific Promoters
• These promoters enable the expression of concerned
genes in specific tissues/organs or during certain
stages of development.
• These promoters drive those genes, which are
expressed specifically in roots, tubers, vascular
bundles, seeds, etc.
• EXAMPLES : Tomato pz7 and pz130 gene promoters
(for ovary gene expression)
Inducible Promoters
• Promoters that are activated in response to a specific
physical factor, i.e., light, temperature, heat, cold,
etc., (physically regulated promoters) or a specific
chemical compound (chemically regulated
promoters) because their expression is normally
restricted to certain plant tissues only.
Synthetic Promoters
• Synthetic promoters are DNA sequences that do not
exist in nature and which are designed to regulate
the activity of genes, controlling a gene’s ability to
produce its own uniquely encoded protein.
• EXAMPLES : Cytomegalovirus (CMV) promoter, Maize
ubiquitin 1 gene (Ubi-1) core promoter
IMPORTANCE :
Thank You !!