title: Molecular mechanism and structural basis of gain-of-function of STAT1 caused by pathogenic R274Q mutation.
abstract: Gain-of-function (GOF) mutations in theSTAT1gene are critical for the onset of chronic mucocutaneous candidiasis (CMC) disease. However, the molecular basis for the gain of STAT1 function remains largely unclear. Here, we investigated the structural features ofSTAT1GOF residues to better understand the impact of these pathogenic mutations. We constructedSTAT1alanine mutants of the α3 helix residues of the coiled-coil domain, which are frequently found in CMC pathogenic mutations, and measured their transcriptional activities. Most of the identified GOF residues were located inside the coiled-coil domain stem structure or at the protein surface of the anti-parallel dimer interface. Unlike those, Arg-274 was adjacent to the DNA-binding domain. In addition, Arg-274 was found to functionally interact with Gln-441 in the DNA-binding domain. Because Gln-441 is located at the anti-parallel dimer contact site, Gln-441 reorientation by Arg-274 mutation probably impedes formation of the dimer. Further, the statistical analysis of RNA-seq data with STAT1-deficient epithelial cells and primary T cells from a CMC patient revealed that the R274Q mutation affected gene expression levels of 66 and 76 non-overlapping RefSeq genes, respectively. Because their transcription levels were only slightly modulated by wild-type STAT1, we concluded that the R274Q mutation increased transcriptional activity but did not change dramatically the repertoire of STAT1 targets. Hence, we provide a novel mechanism ofSTAT1GOF triggered by a CMC pathogenic mutation.
authors.affiliation: From the Department of Technology Development, Kazusa DNA Research Institute, 2-6-7 Kazusa-Kamatari, Kisarazu-Shi, Chiba-Ken, 292-0818, fujiki@kazusa.or.jp.
authors.forename: Ryoji
authors.initials: R
authors.lastname: Fujiki
authors.affiliation: the Nagahama Institute of Bio-Science and Technology, 1266 Tamura, Nagahama-Shi, Shiga-Ken 526-0829, and.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Hijikata
authors.affiliation: the Nagahama Institute of Bio-Science and Technology, 1266 Tamura, Nagahama-Shi, Shiga-Ken 526-0829, and.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Shirai
authors.affiliation: the Graduate School of Biomedical and Health Science, Hiroshima University, 1-2-3, Kasumi, Minami-Ku, Hiroshima-Shi, Hiroshima-Ken 734-8551, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Okada
authors.affiliation: the Graduate School of Biomedical and Health Science, Hiroshima University, 1-2-3, Kasumi, Minami-Ku, Hiroshima-Shi, Hiroshima-Ken 734-8551, Japan.
authors.forename: Masao
authors.initials: M
authors.lastname: Kobayashi
authors.affiliation: From the Department of Technology Development, Kazusa DNA Research Institute, 2-6-7 Kazusa-Kamatari, Kisarazu-Shi, Chiba-Ken, 292-0818.
authors.forename: Osamu
authors.initials: O
authors.lastname: Ohara
mesh_terms: D019943:Amino Acid Substitution; D002178:Candidiasis, Chronic Mucocutaneous / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D057809:HEK293 Cells; D006801:Humans; D020125:Mutation, Missense; D000072417:Protein Domains; D055503:Protein Multimerization / Q000235:genetics*; D017433:Protein Structure, Secondary; D050794:STAT1 Transcription Factor / Q000096:biosynthesis / Q000235:genetics; D013601:T-Lymphocytes / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D050794:STAT1 Transcription Factor; C494079:STAT1 protein, human
keywords: Janus kinase (JAK); genetics; pathogenesis; signal transducers and activators of transcription 1 (STAT1); transcription regulation