5wc9
Human Pit-1 and 4xCATT DNA complex
Structural highlights
DiseasePIT1_HUMAN Hypothyroidism due to deficient transcription factors involved in pituitary development or function;Combined pituitary hormone deficiencies, genetic forms. The disease is caused by mutations affecting the gene represented in this entry. FunctionPIT1_HUMAN Transcription factor involved in the specification of the lactotrope, somatotrope, and thyrotrope phenotypes in the developing anterior pituitary. Specifically binds to the consensus sequence 5'-TAAAT-3'. Activates growth hormone and prolactin genes (PubMed:22010633, PubMed:26612202).[1] [2] Publication Abstract from PubMedOverexpression of the proinflammatory cytokine macrophage migration inhibitory factor (MIF) is linked to a number of autoimmune diseases and cancer. MIF production has been correlated to the number of CATT repeats in a microsatellite region upstream of the MIF gene. We have characterized the interaction of pituitary-specific positive transcription factor 1 (Pit-1) with a portion of the MIF promoter region flanking a microsatellite polymorphism (-794 CATT5-8). Using fluorescence anisotropy, we quantified tight complex formation between Pit-1 and an oligonucleotide consisting of eight consecutive CATT repeats (8xCATT) with an apparent Kd of 35 nM. Using competition experiments we found a 23 base pair oligonucleotide with 4xCATT repeats to be the minimum DNA sequence necessary for high affinity interaction with Pit-1. The stoichiometry of the Pit-1 DNA interaction was determined to be 2:1 and binding is cooperative in nature. We subsequently structurally characterized the complex and discovered a completely novel binding mode for Pit-1 in contrast to previously described Pit-1 complex structures. The affinity of Pit-1 for the CATT target sequence was found to be highly dependent on cooperativity. This work lays the groundwork for understanding transcriptional regulation of MIF and pursuing Pit-1 as a therapeutic target to treat MIF-mediated inflammatory disorders. Biochemical and structural characterization of a novel cooperative binding mode by Pit-1 with CATT repeats in the macrophage migration inhibitory factor promoter.,Agarwal S, Cho TY Nucleic Acids Res. 2017 Nov 23. pii: 4653535. doi: 10.1093/nar/gkx1183. PMID:29186613[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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