Improvement of Vitreoscilla hemoglobin function by Bacillus licheformis glutamate-specific endopeptidase treatment

Vitreoscilla hemoglobin (VHb) was widely used in metabolic engineering to improve oxygen utilization in the low oxygen environment. It is sometimes necessary to remove affinity tags because they may impede functions of target proteins. Here we report an efficient method employing Glutamate-specific endopeptidase from Bacillus licheformis (GSE-BL) to perform the cleavage between VHb and His-tag. The optimal length of GSE-BL treatment was 15 min. Results of SDS–PAGE and western blot demonstrated that the His-tag of VHb-His6 was nearly completely removed, the purity of VHb was enhanced from 74% to 99.5%, and the yield of tagless VHb from VHb-His6 was 92.2%. Results of CO difference spectrum suggested that tagless VHb was more prone to bind to CO compared with VHb-His6. It was observed that tagless VHb displayed higher catalase activity than VHb-His6. The enhancement of welan gum yield was more significant by addition of tagless VHb compared with addition of VHb-His6. This method can be utilized to mass-produce tagless VHb, thus widening the application of VHb in various industries.

► GSE-BL could remove His-tag of VHb-His6 nearly completely in 15 min.
► Tagless VHb was more prone to bind to CO compared with VHb-His6.
► Tagless VHb displayed higher catalase activity than VHb-His6.
► More significant enhancement of welan gum yield was observed for tagless VHb addition.