A method for efficiently secreting and expressing transpeptidase sortase A
A technology of secretion expression and transpeptidase, which is applied in the field of genetic engineering, can solve the problems of the extracellular secretion of the target protein with added concentration and added time, inconsistent effects, inconsistent effects, etc., to shorten the fermentation time, realize industrial production, and save production costs Effect
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Embodiment 1
[0025] Example 1 Extracellular production of Sortase A by E. coli BL21 (DE3)
[0026] The construction method of the recombinant Escherichia coli for producing Sortase A used in the present invention is as follows: taking the genome of S. aureus as a template, and amplifying the N-terminal signal peptide (59 amino acids) with srt-F and srt-R (Table 1) primers The srt gene was ligated with the T vector and transformed into E.coli JM109. After the sequencing was verified to be correct, it was subcloned into plasmids pET22b and pET20b and transformed into E.coli expression host E.coli BL21 (DE3) respectively. The recombinant Escherichia coli (pET22b-srt and pET20b-srt) were induced to express in 250 mL of 25 mL of medium, the induction temperature was 30 °C, the rotational speed was 250 rpm, and the final concentrations of the inducer IPTG were 1 mM / L and 0.4 mM, respectively. / L. The fermentation results showed that the active Sortase A could be detected in the fermentation bro...
Embodiment 2
[0027] Comparative Screening of Different Additives in Example 2
[0028]In order to evaluate the effects of different additives on the extracellular production of Sortase A in Escherichia coli, the effects of different additives on the extracellular Sortase A activity were first screened. The additives were added together with IPTG during induction. Bacillus cell membrane or cell wall has a damaging effect. Considering the cost and toxicity of additives, SDS, glycine, Tween 80, and Triton X-100 were selected as additives in the preliminary test. The results ( figure 1 ) showed that the addition of 0.5% (m / v) glycine significantly promoted the extracellular enzyme activity during induction, while the addition of 5% Tween 80 or 0.5% triton 100 had a significant effect on the extracellular enzyme activity of Sortase A The facilitation effect is almost 0. Therefore, glycine was selected as the additive in the next experiment, and other additives will not be studied here.
Embodiment 3
[0029] Example 3 Screening of different concentrations of glycine
[0030] In order to compare the effects of adding different final concentrations (m / v) of glycine on the extracellular production of Sortase A in E. coli during induction, six addition levels of 0.5%, 0.75%, 1.0%, 1.5%, 2.0% and 2.5% were selected. result( figure 2 ) showed that 0.75% and 1.0% had more obvious promotion effects on the extracellular production of Sortase A, but considering the cost of additives and the growth of bacteria ( image 3 ), the addition concentration of 0.75% is preferred.
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