title: C-terminal motif within Sec7 domain regulates guanine nucleotide exchange activity via tuning protein conformation.
abstract: ADP-ribosylation factors (Arfs) play key roles in controlling membrane traffic and organelle structures. The activation of Arfs from GDP to GTP binding form is triggered by the guanine exchange factors (GEFs). There are six families of Arf-GEFs with a common guanine exchange catalytic domain (Sec7 domain) and various mechanisms of guanine exchange activity regulation. A loop region (loop>J motif) just following the helix J of Sec7 domain was found conserved and important for the catalytic activity regulation of Arf-GEFs. However, the molecular detail of the role the loop>J motif plays has been yet unclear. Here, we studied the catalytic domain of Sec7p, a yeast trans-Golgi network membrane localized Arf-GEFs, and found that the loop>J motif is indispensible for its GEF catalytic activity. Crystallographic, NMR spectrum and mutagenesis studies suggested that the loop>J motif with a key conserved residue Ile1010 modulates the fine conformation of Sec7 domain and thereby regulates its guanine exchange activity.
authors.affiliation: National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; Graduate School of the Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Biao
authors.initials: B
authors.lastname: Qiu
authors.affiliation: National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; Graduate School of the Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Kai
authors.initials: K
authors.lastname: Zhang
authors.affiliation: National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; Graduate School of the Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Shengliu
authors.initials: S
authors.lastname: Wang
authors.affiliation: National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China. Electronic address: feisun@ibp.ac.cn.
authors.forename: Fei
authors.initials: F
authors.lastname: Sun
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001665:Binding Sites / Q000235:genetics; D017124:Conserved Sequence; D018360:Crystallography, X-Ray; D020662:Guanine Nucleotide Exchange Factors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D019906:Nuclear Magnetic Resonance, Biomolecular; D011487:Protein Conformation; D055550:Protein Stability; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D055672:Static Electricity; D040681:Structural Homology, Protein
chemical_list: D020662:Guanine Nucleotide Exchange Factors; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; C066755:Sec7 guanine nucleotide exchange factors
keywords: Crystal structure; Guanine exchange factors; Loop>J motif; Sec7p; Structural stability