Woronin body, a specialized peroxisome, is a unique organelle involved in septal pore sealing and protecting filamentous fungus from excessive cytoplasmic bleeding. We recently characterized the Aohex1 gene encoding the major protein of the Woronin body in the fungus Aspergillus oryzae. Although three-dimensional microscopy revealed plugging of the septal pore by Woronin body, the mechanism of its formation remains unknown. We report here a reduction in the oligomeric forms (dimeric and tetrameric) of AoHex1 upon λ-phosphatase treatment, which indicated that AoHex1 phosphorylation in vivo facilitates its oligomerization. Concomitant with the presence of a highly conserved predicted PKC (protein kinase C)-phosphorylatable site (Ser151), the recombinant AoHex1 was phosphorylated by PKC in vitro and the administration of the PKC inhibitors, bisindolylmaleimide I and chelerythrine, resulted in the reduction of the oligomeric forms of AoHex1 in vivo. While spherical dot-like Woronin bodies were visualized by expressing the dsred2–Aohex1 and egfp (enhanced green fluorescent protein)–Aohex1 constructs in A. oryzae, treatment with the PKC inhibitors caused an abnormal localization to ring-like structures. In addition to the reduced phosphorylation of the mutagenized recombinant AoHex1[S151A] (Ser151 to alanine substitution) by PKC in vitro, the overexpression of Aohex1[S151A] as dsred2 fusion against the wild-type background also showed reduction of the oligomeric forms of the endogenous AoHex1 and its perturbed localization to ring-like structures in vivo. In conclusion, the present study implicates the relevance of PKC-dependent phosphorylation of the Woronin body protein, AoHex1, for its multimerization and proper localization.
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Research Article|
July 13 2007
Phosphorylation of the Aspergillus oryzae Woronin body protein, AoHex1, by protein kinase C: evidence for its role in the multimerization and proper localization of the Woronin body protein
Praveen Rao Juvvadi;
Praveen Rao Juvvadi
1Department of Biotechnology, University of Tokyo, 1-1-1, Yayoi, Bunkyo-Ku, Tokyo 113-8657, Japan
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Jun-ichi Maruyama;
Jun-ichi Maruyama
1Department of Biotechnology, University of Tokyo, 1-1-1, Yayoi, Bunkyo-Ku, Tokyo 113-8657, Japan
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Katsuhiko Kitamoto
Katsuhiko Kitamoto
1
1Department of Biotechnology, University of Tokyo, 1-1-1, Yayoi, Bunkyo-Ku, Tokyo 113-8657, Japan
1To whom correspondence should be addressed (email akitamo@mail.ecc.u-tokyo.ac.jp).
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Publisher: Portland Press Ltd
Received:
November 08 2006
Revision Received:
April 03 2007
Accepted:
April 18 2007
Accepted Manuscript online:
April 18 2007
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© The Authors Journal compilation © 2007 Biochemical Society
2007
Biochem J (2007) 405 (3): 533–540.
Article history
Received:
November 08 2006
Revision Received:
April 03 2007
Accepted:
April 18 2007
Accepted Manuscript online:
April 18 2007
Citation
Praveen Rao Juvvadi, Jun-ichi Maruyama, Katsuhiko Kitamoto; Phosphorylation of the Aspergillus oryzae Woronin body protein, AoHex1, by protein kinase C: evidence for its role in the multimerization and proper localization of the Woronin body protein. Biochem J 1 August 2007; 405 (3): 533–540. doi: https://doi.org/10.1042/BJ20061678
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