title: A neutral protease from Bacillus nematocida, another potential virulence factor in the infection against nematodes.
abstract: A neutral protease (npr) (designated Bae16) toxic to nematodes was purified to homogeneity from the strain Bacillus nematocida. The purified protease showed a molecular mass of approximately 40 kDa and displayed optimal activity at 55 degrees C, pH 6.5. Bioassay experiments demonstrated that this purified protease could destroy the nematode cuticle and its hydrolytic substrates included gelatin and collagen. The gene encoding Bae16 was cloned, and the deduced amino acid sequence showed 94% sequence identity with npr gene from B. amyloliquefaciens, but had low similarity (13-43%) with the previously reported virulence serine proteases from fungi or bacteria, which reflected their differences. Recombinant mature Bae16 (rm-Bae16) was expressed in Escherichia coli BL21 using pET30 vector system, and its nematicidal activity confirmed that Bae16 could be involved in the infection process. Our present study revealed that the npr besides the known alkaline serine protease could serve as a potential virulence factor in the infection against nematodes, furthermore, the two proteases with different characteristics produced by the same strain co-ordinated efforts to kill nematodes. These data helped to understand the interaction between this bacterial pathogen and its host.
authors.affiliation: Laboratory for Conservation and Utilization of Bio-resources, Yunnan University, Kunming, 650091, People's Republic of China.
authors.forename: Qiuhong
authors.initials: Q
authors.lastname: Niu
authors.forename: Xiaowei
authors.initials: X
authors.lastname: Huang
authors.forename: Lin
authors.initials: L
authors.lastname: Zhang
authors.forename: Yunxia
authors.initials: Y
authors.lastname: Li
authors.forename: Juan
authors.initials: J
authors.lastname: Li
authors.forename: Jinkui
authors.initials: J
authors.lastname: Yang
authors.forename: Keqin
authors.initials: K
authors.lastname: Zhang
mesh_terms: D000818:Animals; D000969:Antinematodal Agents / Q000494:pharmacology; D001407:Bacillus / Q000201:enzymology / Q000235:genetics* / Q000472:pathogenicity; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000494:pharmacology; D002852:Chromatography, Ion Exchange / Q000379:methods; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D004789:Enzyme Activation / Q000187:drug effects; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D009348:Nematoda / Q000187:drug effects / Q000382:microbiology; D010447:Peptide Hydrolases / Q000737:chemistry / Q000235:genetics* / Q000494:pharmacology; D011480:Protease Inhibitors / Q000494:pharmacology; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA; D020539:Sequence Analysis, Protein; D013696:Temperature; D014774:Virulence / Q000235:genetics
chemical_list: D000969:Antinematodal Agents; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D011480:Protease Inhibitors; D011994:Recombinant Proteins; D010447:Peptide Hydrolases