title: Tip-to-nucleus migration dynamics of the asexual development regulator FlbB in vegetative cells.
abstract: In Aspergillus nidulans, asexual differentiation requires the presence of the transcription factor FlbB at the cell tip and apical nuclei. Understanding the relationship between these two pools is crucial for elucidating the biochemical processes mediating conidia production. Tip-to-nucleus communication was demonstrated by photo-convertible FlbB::Dendra2 visualization. Tip localization of FlbB depends on Cys382 in the C-terminus and the bZIP DNA-binding domain in the N-terminus. FlbE, a critical FlbB interactor, binds the bZIP domain. Furthermore, the absence of FlbE results in loss of tip localization but not nuclear accumulation. flbE deletion also abrogates transcriptional activity indicating that FlbB gains transcriptional competence from interactions with FlbE at the tip. Finally, a bipartite nuclear localization signal is required for nuclear localization of FlbB. Those motifs of FlbB may play various roles in the sequence of events necessary for the distribution and activation of this transcriptionally active developmental factor. The tip accumulation, FlbE-dependent activation, transport and nuclear import sketch out a process of relaying an environmentally triggered signal from the tip to the nuclei. As the first known instance of transcription factor-mediated tip-to-nucleus communication in filamentous fungi, this provides a general framework for analyses focused on elucidating the set of molecular mechanisms coupling apical signals to transcriptional events.
authors.affiliation: Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas (CSIC), Ramiro de Maeztu 9, 28040, Madrid, Spain.
authors.forename: Erika
authors.initials: E
authors.lastname: Herrero-Garcia
authors.affiliation: Biochemistry II laboratory, Department of Applied Chemistry, Faculty of Chemistry, University of The Basque Country, 20018, San Sebastian, Spain.
authors.forename: Elixabet
authors.initials: E
authors.lastname: Perez-de-Nanclares-Arregi
authors.affiliation: Biochemistry II laboratory, Department of Applied Chemistry, Faculty of Chemistry, University of The Basque Country, 20018, San Sebastian, Spain.
authors.forename: Marc S
authors.initials: MS
authors.lastname: Cortese
authors.affiliation: Biochemistry II laboratory, Department of Applied Chemistry, Faculty of Chemistry, University of The Basque Country, 20018, San Sebastian, Spain.
authors.forename: Ane
authors.initials: A
authors.lastname: Markina-Iñarrairaegui
authors.affiliation: Biochemistry II laboratory, Department of Applied Chemistry, Faculty of Chemistry, University of The Basque Country, 20018, San Sebastian, Spain.
authors.forename: Elixabet
authors.initials: E
authors.lastname: Oiartzabal-Arano
authors.affiliation: Biochemistry II laboratory, Department of Applied Chemistry, Faculty of Chemistry, University of The Basque Country, 20018, San Sebastian, Spain.
authors.forename: Oier
authors.initials: O
authors.lastname: Etxebeste
authors.affiliation: Biochemistry II laboratory, Department of Applied Chemistry, Faculty of Chemistry, University of The Basque Country, 20018, San Sebastian, Spain.
authors.forename: Unai
authors.initials: U
authors.lastname: Ugalde
authors.affiliation: Department of Cellular and Molecular Biology, Centro de Investigaciones Biológicas (CSIC), Ramiro de Maeztu 9, 28040, Madrid, Spain.
authors.forename: Eduardo A
authors.initials: EA
authors.lastname: Espeso
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001233:Aspergillus nidulans / Q000166:cytology / Q000235:genetics* / Q000254:growth & development* / Q000378:metabolism; D050976:Basic-Leucine Zipper Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D025301:Hyphae / Q000235:genetics / Q000254:growth & development; D019913:Nuclear Localization Signals; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013172:Spores, Fungal / Q000254:growth & development / Q000378:metabolism; D015533:Transcriptional Activation
chemical_list: D050976:Basic-Leucine Zipper Transcription Factors; D005656:Fungal Proteins; D019913:Nuclear Localization Signals