Figure 7

Screening for the production of for other human proteins using Erv1p plus a disulfide isomerase pre-expression system. Panel A) Coomassie stained reducing SDS-PAGE analysis of mature human proteins produced in the cytoplasm of BL21 (DE3) pLysS with different growth media. T = total E. coli lysate S = soluble fraction. The positions of the proteins are marked with arrows. The data shown is from Ero1α with pre-expression of Erv1p and mature PDI; MBP-tagged CSF3 with pre-expression of Erv1p and mature DsbC and co-expression of Erv1p and mature PDI; MBPx-tagged BMP4 with pre-and co-expression of Erv1p and DsbC; MBPx-light chain of enterokinase Cys896Ser with pre-expression of Erv1p and DsbC. Many other variants and combinations of pre- and co-expression conditions have been tested (see additional file 2: Table of vectors used in this study). For all four of these proteins under all conditions tested there is a concomitant increase in the number of disulfide bonds and yields of monomeric protein upon co- or pre-expression of Erv1p and a disulfide isomerase. Panel B) Reducing SDS-PAGE analysis of mature human proteins produced in the cytoplasm of origami in EnBase media with pre-expression of Erv1p and DsbC. T = total E. coli lysate, S = soluble fraction, P = protein purified using an NTA-spin column or amylose column. The molecular weights (in kDa) of the markers (mw) are indicated.