title: GBF/Gea mutant with a single substitution sustains fungal growth in the absence of BIG/Sec7.
abstract: Golgi Arf1-guanine nucleotide exchange factors (GEFs) belong to two subfamilies: GBF/Gea and BIG/Sec7. Both are conserved across eukaryotes, but the physiological role of each is not well understood. Aspergillus nidulans has a single member of the early Golgi GBF/Gea-subfamily, geaA, and the late Golgi BIG/Sec7-subfamily, hypB. Both geaA and hypB are essential. hypB5 conditionally blocks secretion. We sought extragenic hypB5 suppressors and obtained geaA1. geaA1 results in Tyr1022Cys within a conserved GBF/Gea-specific S(Y/W/F)(L/I) motif in GeaA. This mutation alters GeaA localization. Remarkably, geaA1 suppresses hypBΔ, indicating that a single mutant Golgi Arf1-GEF suffices for growth.
authors.affiliation: Section of Microbiology, Department of Medicine, Imperial College London, London SW7 2AZ, United Kingdom; Centro de Investigaciones Biológicas, CSIC, Madrid 28040, Spain.
authors.forename: Herbert N
authors.initials: HN
authors.lastname: Arst
authors.affiliation: Centro de Investigaciones Biológicas, CSIC, Madrid 28040, Spain.
authors.forename: Miguel
authors.initials: M
authors.lastname: Hernandez-Gonzalez
authors.affiliation: Centro de Investigaciones Biológicas, CSIC, Madrid 28040, Spain.
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Peñalva
authors.affiliation: Centro de Investigaciones Biológicas, CSIC, Madrid 28040, Spain. Electronic address: apantazopoulou@cib.csic.es.
authors.forename: Areti
authors.initials: A
authors.lastname: Pantazopoulou
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001232:Aspergillus fumigatus / Q000166:cytology / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D020662:Guanine Nucleotide Exchange Factors / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D042541:Intracellular Space / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D021381:Protein Transport
chemical_list: D005656:Fungal Proteins; D020662:Guanine Nucleotide Exchange Factors
keywords: BIG/Sec7-subfamily; Fungal secretion; GBF/Gea-subfamily; Golgi Arf1-GEFs