The Prokaryotic expression of TasA protein of Bacillus subtilis strain A6 in Escherichia coli BL21(DE3)

TasA protein of Bacillus subtitlis was reported to have a broadspectrum of antibacterial activities. The TasA open reading frame (ORF) was PCR-amplified from A6, and cloned into pMD18-T. Sequence analysis of the clone indicated that the TasA ORF consists of 786 nucleotides, and shared 99.24% homology at nucleotide sequence, and 100% identitiy at amino acid sequence between it and the published gene TasA (corresponded with 143163~143948) from Bacillus subtilis (Accession No:Z99116). The nucleotide sequence variations were base transitions (A/G or C/T substitution), and occurred on their third base of the codons in the ORF. The second structure and the amino acid sequence of TasA protein were predicted by using the software (http://npsa-pbil.ibcp.fr/cgi-bin/secpred_mlr.pl). In order to understand the molecular function of TasA protein, the TasA gene was cloned into expression vector pET-TasA, and expressed in E. coli BL21. A unique 33kD fusion protein product was detected by SDS-PAGE, which indicated the TasA protein was expressed correctly in E. coli BL21.