title: Purification and characterization of a neutral serine protease with nematicidal activity from Hirsutella rhossiliensis.
abstract: Serine protease plays an important role in fungal infection to invertebrate hosts. An extracellular protease (Hnsp) was detected in liquid culture of Hirsutella rhossiliensis OWVT-1 with nematodes (Panagrellus redivivus) as the unique nitrogen source and purified to homogeneity by ammonium sulphate precipitation, anion exchange chromatography and gel filtration. Its molecular mass was about 32 kDa, and the optimal reaction pH value and temperature were pH 7 and 40 degrees C, respectively. The Hnsp activity was stable at pH 6-8 and decreased radically at 50 degrees C for 10 min. Hnsp was highly sensitive to inhibitor of PMSF and well decomposed the substrate N-succinyl-Ala-Ala-Pro-Phe-p-nitroanilide, suggesting that it belonged to the chymotrypsin/subtilisin of serine proteases. The N-terminal amino acid sequence of Hnsp was SVTDQQGADCGLARISHRE, which showed high homology with other serine proteases from nematophagous fungi. Ability to kill nematode and degrade its cuticle in vitro indicated that Hnsp could be involved in the infection of nematode.
authors.affiliation: Key Laboratory of Systematic Mycology and Lichenology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, 100080, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Wang
authors.forename: Wenping
authors.initials: W
authors.lastname: Wu
authors.forename: Xingzhong
authors.initials: X
authors.lastname: Liu
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000969:Antinematodal Agents / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism / Q000494:pharmacology*; D006863:Hydrogen-Ion Concentration; D006999:Hypocreales / Q000201:enzymology*; D008969:Molecular Sequence Data; D009348:Nematoda / Q000187:drug effects*; D010664:Phenylmethylsulfonyl Fluoride / Q000494:pharmacology; D011480:Protease Inhibitors / Q000494:pharmacology; D020539:Sequence Analysis, Protein; D012697:Serine Endopeptidases / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism / Q000494:pharmacology*; D013379:Substrate Specificity; D013696:Temperature
chemical_list: D000969:Antinematodal Agents; D011480:Protease Inhibitors; D010664:Phenylmethylsulfonyl Fluoride; D012697:Serine Endopeptidases