hex-1, a gene unique to filamentous fungi, encodes the major protein of the Woronin body and functions as a plug for septal pores

Tenney, K., Hunt, I., Sweigard, J., Pounder, J., McClain, C., Bowman, E, J, , and Bowman, B, 2000. hex-1, a gene unique to filamentous fungi, encodes t he major protein of the Woronin body and functions as a plug for septal por es, Fungal Genetics and Biology 31, 205-217. We have identified a gene, nam ed hex-l, that encodes the major protein in the hexagonal crystals, or Woro nin bodies, of Neurospora crassa. Analysis of a strain with a null mutation in the hex-1 gene showed that the septal pores in this organism were not p lugged when hyphae were damaged, leading to extensive loss of cytoplasm. Wh en grown on agar plates containing sorbose, the hex-1(-) strain showed exte nsive lysis of hyphal tips. The HEX-1 protein was predicted to be 19,125 Da . Analysis of the N-terminus of the purified protein indicated that 16 resi dues are cleaved, yielding a protein of 17,377 Da. A polyclonal antibody ra ised to the HEX-1 protein recognized multiple forms of the protein, apparen tly dimers and tetramers that were resistant to solubilization by sodium do decyl sulfate and reducing reagents, Treatment of the protein with phosphat ase caused dissociation of these oligomers. Preparations enriched in Woroni n bodies contained catalase activity, which was not detected in comparable fractions from the hex-1(-) mutant strain. These results support the hypoth esis that the Woronin body is a specialized peroxisome that functions as a plug for septal pores, (C) 2000 Academic Press.