Replacement of the C-terminal tetrapeptide (314PAPV317 to 314SSSM317) in interferon regulatory factor-2 alters its N-terminal DNA-binding activity.
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2010-12
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Abstract
Interferon regulatory factor-2 (IRF-2) is an important transcription factor involved in cell growth regulation, immune
response and cancer. IRF-2 can function as a transcriptional repressor and activator depending on its DNA-binding
activity and protein–protein interactions. We compared the amino acid sequences of IRF-2 and found a C-terminal
tetrapeptide (314PAPV317) of mouse IRF-2 to be different (314SSSM317) from human IRF-2. Recombinant GST-IRF-2
with 314PAPV317 (wild type) and 314SSSM317 (mutant) expressed in Escherichia coli were assessed for DNA-binding
activity with 32P-(GAAAGT)
4
by electrophoretic mobility shift assay (EMSA). Wild type- and mutant GST-IRF-2
showed similar expression patterns and immunoreactivities but different DNA-binding activities. Mutant (mt) IRF-2
formed higher-molecular-mass, more and stronger DNA–protein complexes in comparison to wild type (wt) IRF-2.
Anti-IRF-2 antibody stabilized the DNA–protein complexes formed by both wt IRF-2 and mt IRF-2, resolving the
differences. This suggests that PAPV and SSSM sequences at 314-317 in the C-terminal region of mouse and human
IRF-2 contribute to conformation of IRF-2 and infl uence DNA-binding activity of the N-terminal region, indicating
intramolecular interactions. Thus, evolution of IRF-2 from murine to human genome has resulted in subtle differences
in C-terminal amino acid motifs, which may contribute to qualitative changes in IRF-2-dependent DNA-binding
activity and gene expression.
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Prakash Krishna, Rath Pramod C. Replacement of the C-terminal tetrapeptide (314PAPV317 to 314SSSM317) in interferon regulatory factor-2 alters its N-terminal DNA-binding activity. Journal of Biosciences. 2010 Dec; 35(4): 547-556.