title: Purification and characterization of an extracellular serine protease from the nematode-trapping fungus Dactylella shizishanna.
abstract: OBJECTIVE
  To evaluate the production of an extracellular serine protease by Dactylella shizishanna and its potential as a pathogenesis factor.
  
  
  RESULTS
  An extracellular alkaline serine protease (Ds1) was purified and characterized from the nematode-trapping fungus D. shizishanna using cation-exchange chromatography and hydrophobic interaction chromatography. The molecular mass of the protease was approximately 35 kDa estimated by SDS-PAGE. The optimum activity of Ds1 was at pH 10 and 55 degrees C (over 30 min). The purified protease could degrade purified cuticle of Penagrellus redivivus and a broad range of protein substrates. The purified protease was highly sensitive to phenylmethyl sulfonyl fluoride (PMSF) (0.1 mmol l(-1)), indicating it belonged to the serine protease family. The N-terminal amino acid residues of Ds1 are AEQTDSTWGL and showed a high homology with Aozl and PII, two serine proteases purified from the nematode-trapping fungus Arthrobotrys oligospora.
  
  
  CONCLUSIONS
  Nematicidal activity of D. shizishanna was partly related to its ability to produce extracellular serine protease.
  
  
  CONCLUSIONS
  In this report, we purified a new serine protease from D. shizishanna and provided a good foundation for future research on infection mechanism.
authors.affiliation: Laboratory for Conservation and Utilization of Bio-resources, Yunnan University, Kunming, China.
authors.forename: R B
authors.initials: RB
authors.lastname: Wang
authors.forename: J K
authors.initials: JK
authors.lastname: Yang
authors.forename: C
authors.initials: C
authors.lastname: Lin
authors.forename: Y
authors.initials: Y
authors.lastname: Zhang
authors.forename: K Q
authors.initials: KQ
authors.lastname: Zhang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D005656:Fungal Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D005658:Fungi / Q000201:enzymology* / Q000472:pathogenicity*; D006863:Hydrogen-Ion Concentration; D009348:Nematoda / Q000378:metabolism / Q000382:microbiology*; D012697:Serine Endopeptidases / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D013696:Temperature
chemical_list: D005656:Fungal Proteins; D012697:Serine Endopeptidases