AP2/EREBP Transcription Factor Family

Garen and Joanna

Transcription Factors

Transcription Factors (TF) are proteins that regulate the transcription of genes

Three general categories of TFs Bind to RNA Polymerase Bind to another TF Bind to specific DNA sequences

Most bind upstream of the target gene in the promoter sequence

What is AP2?

AP2 derives name from APETALA2 protein Domain sequence of 70 amino acids

Unique to Plants Contain either 1 or 2 AP2 Domains

EREBP and AP2 subfamilies Present during many stages of plant

development in all organs Our focus is seed development

3 Types of AP2 Proteins

Three classes of single AP2 repeat proteins Ethylene Response Elements Binding Proteins

(EREBPs) Dehydration Response Elements (DREs) RAV1 and RAV2

Sub-families of AP2

Sub-family EREBP RAV DRE

Binding

Sequence

TAAGAGCCG

CC CAACA+

CACCTG

[ag]CCGAC

What is its role in plants?

Are involved in various aspects of plant growth and development Flower Development Hormone signal transduction Cellular Differentiation

Responds to biotic and abiotic stresses Drought (DREs) Low Temperature Pathogens

More specifically…

Certain AP2 genes control seed mass and seed size in Arabidopsis.

May negatively affect gibberellin activity in regulating cell size and number during seed development

Large seed size correlates with deformed flowers

Mechanisms

Seed size affected two different ways when AP2-10 is non-functional

1) Seed cavity size enlarged This allows for extended growth of

cotyledons

2) Prolonged mitotic activity after torpedo stage leads results in extended growth of embryo

Wildtype Seed

Wildtype Seed Coat

Mutant Seed

Mutant Seed Coat

Conclusion

AP2 transcription factors are crucial to many plant processes

Its effects on seed development may have significant repercussions in other organs, as exemplified by deformed flowers

Masking? There’s still much we don’t know, but the

research continues