Dynamic distribution of BIMG(PP1) in living hyphae of Aspergillus indicates a novel role in septum formation.
Mutation of bimG, the major protein phosphatase 1 gene in Aspergillus nidulans, causes multiple cell cycle and hyphal growth defects that are associated with overphosphorylation of subcellular components. We have used functional translational fusions with the green fluorescent protein (GFP) to show that BIMG has at least four discrete locations within growing hyphae. Three of these locations, the hyphal tip, the spindle pole body and the nucleus, correlate with previously known requirements for bimG(PP1) in mitosis and hyphal growth and are highly dynamic. BIMG-GFP in the hyphal tip seemed to be associated with the plasma membrane and formed a collar of fluorescence within the apical dome. The distribution of nuclear BIMG-GFP varied depending on nutritional conditions; on poor medium, it concentrated more in the nucleolus than in the nucleoplasm, whereas on rich medium, it was more evenly distributed between the two nuclear regions. The association of BIMG-GFP with developing septa was transient, and we present evidence that BIMG phosphatase plays a direct role in septum formation, distinct from its role in mitosis. We conclude that, by being physically present at several sites, the BIMG phosphatase has roles in multiple cellular processes.
Fox
H
H
John Innes Centre, Colney Lane, Norwich NR4 7UH, UK.
Hickey
P C
PC
Fernández-Abalos
J M
JM
Lunness
P
P
Read
N D
ND
Doonan
J H
JH
D001233:Aspergillus nidulans / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development*; D002467:Cell Nucleus / Q000201:enzymology; D002473:Cell Wall / Q000201:enzymology; D003470:Culture Media; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D005800:Genes, Fungal; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D010749:Phosphoprotein Phosphatases / Q000235:genetics / Q000378:metabolism*; D054645:Protein Phosphatase 1; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism
D003470:Culture Media; D005656:Fungal Proteins; D008164:Luminescent Proteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1