Question

The GATA family of transcription factors are important regulators of cell identity. The family member GATA1 is absolutely required for the switch from an immature erythroid cell into a mature red blood cell. As part of this switch, GATA1 binds to the consensus DNA sequence GATAAA through interactions with the DNA major groove. One of the results is the massive upregulation of globin mRNA. Design a set of experiments to demonstrate that GATA1 binds to GATAAA containing sequences and does so through major groove recognition/binding mechanisms.

Answer 1

• GATA1 organizes erythroid and megakaryocytic differentiation by orchestrating the expression of multiple genes that show diversified expression profiles. Demonstrate that GATA1 monovalently binds to single GATA motif while a monomeric GATA1 and homodimeric GATA1 bivalently binds to two GATA motifs in palindromic and direct-repeat arrangements.
• The amino terminal Zinc finger of GATA1 critically contributes high occupancy of GATA1 on PAL-GATA. GATA1 lacking the N finger DNA association fails to trigger a rate of target gene expression comparable to that seen with the wild type GATA1 target genes distinct from the response of single GATA.
• The binding member of the GATA family of transcription factors, which is composed of 6 members in vertebrates.
• GATA1 has four functional domains i.e., two transactivationdomains residing in amino and carboxyl termini, which transactivate GATA1 target genes redundantly and two zinc finger domains in the middle of the protein. The carboxyl terminal zinc finger retains insufficient binding activity to GATA motifs by itself but contributes to stabilize the binding of the C finger to a double GATA site arranged in a palindromic manner.
• It has been found that binding motifs for other transcription factors are differntially enriched adjacent to GATA motifs at both the GATA1 activated and repressed genes and this differential enrichment occurs at erythroid specific and megakaryocyte specific gene.