title: Mining new crystal protein genes from Bacillus thuringiensis on the basis of mixed plasmid-enriched genome sequencing and a computational pipeline.
abstract: We have designed a high-throughput system for the identification of novel crystal protein genes (cry) from Bacillus thuringiensis strains. The system was developed with two goals: (i) to acquire the mixed plasmid-enriched genomic sequence of B. thuringiensis using next-generation sequencing biotechnology, and (ii) to identify cry genes with a computational pipeline (using BtToxin_scanner). In our pipeline method, we employed three different kinds of well-developed prediction methods, BLAST, hidden Markov model (HMM), and support vector machine (SVM), to predict the presence of Cry toxin genes. The pipeline proved to be fast (average speed, 1.02 Mb/min for proteins and open reading frames [ORFs] and 1.80 Mb/min for nucleotide sequences), sensitive (it detected 40% more protein toxin genes than a keyword extraction method using genomic sequences downloaded from GenBank), and highly specific. Twenty-one strains from our laboratory's collection were selected based on their plasmid pattern and/or crystal morphology. The plasmid-enriched genomic DNA was extracted from these strains and mixed for Illumina sequencing. The sequencing data were de novo assembled, and a total of 113 candidate cry sequences were identified using the computational pipeline. Twenty-seven candidate sequences were selected on the basis of their low level of sequence identity to known cry genes, and eight full-length genes were obtained with PCR. Finally, three new cry-type genes (primary ranks) and five cry holotypes, which were designated cry8Ac1, cry7Ha1, cry21Ca1, cry32Fa1, and cry21Da1 by the B. thuringiensis Toxin Nomenclature Committee, were identified. The system described here is both efficient and cost-effective and can greatly accelerate the discovery of novel cry genes.
authors.affiliation: State Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China.
authors.forename: Weixing
authors.initials: W
authors.lastname: Ye
authors.forename: Lei
authors.initials: L
authors.lastname: Zhu
authors.forename: Yingying
authors.initials: Y
authors.lastname: Liu
authors.forename: Neil
authors.initials: N
authors.lastname: Crickmore
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: D001413:Bacillus thuringiensis / Q000235:genetics* / Q000378:metabolism; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D019295:Computational Biology / Q000379:methods*; D004731:Endotoxins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D016680:Genome, Bacterial; D006460:Hemolysin Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D059014:High-Throughput Nucleotide Sequencing / Q000379:methods*; D010957:Plasmids / Q000235:genetics*; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA / Q000379:methods*
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D004731:Endotoxins; D006460:Hemolysin Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis