title: Bacillus thuringiensis metalloproteinase Bmp1 functions as a nematicidal virulence factor.
abstract: Some Bacillus thuringiensis strains have high toxicity to nematodes. Nematicidal activity has been found in several families of crystal proteins, such as Cry5, Cry6, and Cry55. The B. thuringiensis strain YBT-1518 has three cry genes that have high nematicidal activity. The whole genome sequence of this strain contains multiple potential virulence factors. To evaluate the pathogenic potential of virulence factors, we focused on a metalloproteinase called Bmp1. It encompasses a consecutive N-terminal signal peptide, an FTP superfamily domain, an M4 neutral protease GluZincin superfamily, two Big-3 superfamily motifs, and a Gram-positive anchor superfamily motif as a C-terminal domain. Here, we showed that purified Bmp1 protein showed metalloproteinase activity and toxicity against Caenorhabditis elegans (the 50% lethal concentration is 610 ± 9.37 μg/ml). In addition, mixing Cry5Ba with Bmp1 protein enhanced the toxicity 7.9-fold (the expected toxicity of the two proteins calculated from their separate toxicities) against C. elegans. Confocal microscopic observation revealed that Bmp1 protein was detected from around the mouth and esophagus to the intestine. Striking microscopic images revealed that Bmp1 degrades intestine tissues, and the Cry5Ba causes intestinal shrinkage from the body wall. Thus, the B. thuringiensis Bmp1 metalloproteinase is a nematicidal virulence factor. These findings give a new insight into the relationship between B. thuringiensis and its host nematodes.
authors.affiliation: State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, China.
authors.forename: Xiaoxia
authors.initials: X
authors.lastname: Luo
authors.forename: Ling
authors.initials: L
authors.lastname: Chen
authors.forename: Qiong
authors.initials: Q
authors.lastname: Huang
authors.forename: Jinshui
authors.initials: J
authors.lastname: Zheng
authors.forename: Wei
authors.initials: W
authors.lastname: Zhou
authors.forename: Donghai
authors.initials: D
authors.lastname: Peng
authors.forename: Lifang
authors.initials: L
authors.lastname: Ruan
authors.forename: Ming
authors.initials: M
authors.lastname: Sun
mesh_terms: D000818:Animals; D000871:Anthelmintics / Q000302:isolation & purification / Q000378:metabolism; D001413:Bacillus thuringiensis / Q000201:enzymology* / Q000472:pathogenicity*; D017173:Caenorhabditis elegans / Q000187:drug effects* / Q000502:physiology; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D007422:Intestines / Q000473:pathology; D007928:Lethal Dose 50; D045726:Metalloproteases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D018613:Microscopy, Confocal; D008969:Molecular Sequence Data; D017422:Sequence Analysis, DNA; D016019:Survival Analysis; D037521:Virulence Factors / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D000871:Anthelmintics; D004269:DNA, Bacterial; D037521:Virulence Factors; D045726:Metalloproteases