Abstract
Mosquitocidal Bacillus thuringiensis (Bt) strain S2160-1 was proposed to be an alternative to Bacillus thuringiensis subsp. israelensis (Bti). Discovering and validating a toxic gene by experimentation was a complex and time-consuming task, which can benefit from high-throughput sequencing analysis. In this research, we predicted and identified toxic proteins in the strain S2160-1 based on the draft whole genome sequence data. Through a local BLASP, 46 putative toxins were identified in S2160-1 genome, by searching against a customized B. thuringiensis toxin proteins database containing 653 protein or peptide sequences retrieved from public accessible resources and PCR/clone results in our laboratory (e value = 1e − 5). These putative toxins consist of 42 to 1216 amino acids. The molecular weights are ranged from 4.86 to 137.28 kDa. The isoelectric point of these candidate toxins varied from 4.3 to 10.06, and 16 out of which had a pH greater than 7.0. The analysis of tertiary structure and PFAM domain showed that 12 potential plasmid toxins may share higher similarity (9/12 QMEAN4 score > 0.3) with known Bt toxins. In addition, functional annotation indicated that these 12 potential toxins were involved in “sporulation resulting in formation of a cellular spore” and “toxin activity”. Moreover, multiple alignment and phylogenetic analysis were carried out to elucidate the evolutionary relationship among 101 known crystal or toxin proteins from public database and them with MEGA 6.0. It indicated that PS2160P2_1 and PS2160P2_153 may be potential Cry4-like toxins in Bt S2160-1. This research may lay the foundation for future functional analysis of Bt S2160-1 toxin proteins to reveal their biological roles.
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Abbreviations
- CTGs:
-
Candidate toxin genes
- TER-CTGs:
-
Candidate toxin genes with tertiary structure
- CD-CTGs:
-
Candidate toxin genes with conserved domain
- GO-CTGs:
-
Candidate toxin genes with GO annotations
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Acknowledgements
This work was part of the project “China National Bt Strains Resource Initiative (BtSRI)” funded by Hainan Institute of Tropical Agricultural Resources in Hainan province (HITAR). All the intellectual property rights are owned by HITAR in Hainan province.
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Liu, P., Zhou, Y., Wu, Z. et al. Computational identification and evolutionary analysis of toxins in Mosquitocidal Bacillus thuringiensis strain S2160-1. 3 Biotech 8, 293 (2018). https://doi.org/10.1007/s13205-018-1313-0
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DOI: https://doi.org/10.1007/s13205-018-1313-0