Replacement of 198MQMDII203 of mouse IRF-1 by 197IPVEVV202 of human IRF-1 abrogates induction of IFN-beta, iNOS, and COX-2 gene expression by IRF-1.
Interferon regulatory factor-1 (IRF-1) is a transcription factor exhibiting functional diversity because of its ability to activate transcription from promoters of several IRF-1-dependent genes. It is a modular protein, where the overall structure is not essential for function of its individual domains. A comparison of the mouse and human IRF-1 amino acid sequences enabled us to identify a stretch of six amino acids (198-203) within the transactivation domain of mouse IRF-1, 198MQMDII(203) to be different from that of the human IRF-1, 197IPVEVV(202). This indicated a possible functional significance of the six amino acid stretches in the two IRF-1 molecules. The murine IRF-1 sequence at 198-203 (MQMDII) was replaced by IPVEVV. Recombinant wild type mouse IRF-1 with 198MQMDII(203) and its mutant form with 198IPVEVV(203), expressed as GST-IRF-1-fusion proteins, showed similar DNA-binding activity. However, ectopic expression of the wild type and mutant IRF-1 in the human embryonic kidney (HEK-293) cells showed the effect of replacement of this region on expression of a few chromosomal genes that are transcriptionally activated by IRF-1 viz. IFN-beta, iNOS, and COX-2 genes. In our study, expression of wild type IRF-1 activated these genes as judged by RT-PCR but the mutant IRF-1 did not show this effect. Thus, the MQMDII (198-203 a.a.) region of mouse IRF-1 has a functional context in relation to expression of IRF-1-inducible genes.
Upreti
Meenakshi
M
Molecular Biology Laboratory, School of Life Sciences, Jawaharlal Nehru University, 110067, New Delhi, India.
Kumar
Sanjiv
S
Rath
Pramod C
PC
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D002460:Cell Line; D051546:Cyclooxygenase 2; D004247:DNA / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D004926:Escherichia coli / Q000378:metabolism; D005786:Gene Expression Regulation / Q000235:genetics*; D006801:Humans; D050856:Interferon Regulatory Factor-1; D016899:Interferon-beta / Q000096:biosynthesis* / Q000235:genetics; D007527:Isoenzymes / Q000096:biosynthesis* / Q000235:genetics; D008565:Membrane Proteins; D051379:Mice; D008969:Molecular Sequence Data; D019001:Nitric Oxide Synthase / Q000096:biosynthesis* / Q000235:genetics; D052247:Nitric Oxide Synthase Type II; D010750:Phosphoproteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D011451:Prostaglandin-Endoperoxide Synthases / Q000096:biosynthesis* / Q000235:genetics; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000032:analysis / Q000096:biosynthesis; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D015533:Transcriptional Activation / Q000235:genetics; D014162:Transfection
D004268:DNA-Binding Proteins; C494257:IRF1 protein, human; D050856:Interferon Regulatory Factor-1; C494258:Irf1 protein, mouse; D007527:Isoenzymes; D008565:Membrane Proteins; D010750:Phosphoproteins; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D016899:Interferon-beta; D004247:DNA; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases