title: Timely septation requires SNAD-dependent spindle pole body localization of the septation initiation network components in the filamentous fungus Aspergillus nidulans.
abstract: In the filamentous fungus Aspergillus nidulans, cytokinesis/septation is triggered by the septation initiation network (SIN), which first appears at the spindle pole body (SPB) during mitosis. The coiled-coil protein SNAD is associated with the SPB and is required for timely septation and conidiation. We have determined that SNAD acted as a scaffold protein that is required for the localization of the SIN proteins of SIDB and MOBA to the SPB. Another scaffold protein SEPK, whose localization at the SPB was dependent on SNAD, was also required for SIDB and MOBA localization to the SPB. In the absence of either SEPK or SNAD, SIDB/MOBA successfully localized to the septation site, indicating that their earlier localization at SPB was not essential for their later appearance at the division site. Unlike their functional counterparts in fission yeast, SEPK and SNAD were not required for vegetative growth but only for timely septation. Furthermore, down-regulation of negative regulators of the SIN suppressed the septation and conidiation phenotypes due to the loss of SNAD. Therefore, we conclude that SPB localization of SIN components is not essential for septation per se, but critical for septation to take place in a timely manner in A. nidulans.
authors.affiliation: Department of Plant Biology, College of Biological Sciences, University of California, Davis, CA 95616, USA.
authors.forename: Jung-Mi
authors.initials: JM
authors.lastname: Kim
authors.forename: Cui Jing Tracy
authors.initials: CJ
authors.lastname: Zeng
authors.forename: Tania
authors.initials: T
authors.lastname: Nayak
authors.forename: Rongzhong
authors.initials: R
authors.lastname: Shao
authors.forename: An-Chi
authors.initials: AC
authors.lastname: Huang
authors.forename: Berl R
authors.initials: BR
authors.lastname: Oakley
authors.forename: Bo
authors.initials: B
authors.lastname: Liu
mesh_terms: D000205:Actomyosin / Q000378:metabolism; D001233:Aspergillus nidulans / Q000166:cytology* / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000378:metabolism*; D048749:Cytokinesis; D015536:Down-Regulation; D005656:Fungal Proteins / Q000378:metabolism*; D020690:GTPase-Activating Proteins / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D021381:Protein Transport; D017386:Sequence Homology, Amino Acid; D008941:Spindle Apparatus / Q000378:metabolism*; D013997:Time Factors
chemical_list: D018797:Cell Cycle Proteins; D005656:Fungal Proteins; D020690:GTPase-Activating Proteins; C409364:SNAD protein, Aspergillus nidulans; D000205:Actomyosin