Filamentation in <i>Escherichia coli</i> Induced by Recombinant Alcohol Dehydrogenase Accumulation

Heat shock proteins (Hsps) are co-expressed with recombinant proteins to facilitate proper protein folding and accumulation.However, Hsp co-expression often results in adverse side effects of reduced recombinant protein yield and solubility.In this study, we compared the recombinant alcohol dehydrogenase (ADH) accumulation in transformed Escherichia coli (E.coli) constitutively expressing carrot (Daucus carota L.) DcHsp17.7 or DcHsp70, whose genes were inserted into the bacterial genome, with that in the transformed E. coli expressing DcHsp17.7 or DcHsp70 upon the isopropyl -D-1-thiogalactopyranoside (IPTG) treatment.The constitutive DcHsp70 expression resulted in a 2.6-fold higher level of recombinant ADH accumulation than expressing recombinant ADH alone, while the IPTG-induced DcHsp70 expression reduced the ADH accumulation to 0.3-fold.In contrast, the constitutive expression of DcHsp17.7 only slightly increased ADH by 1.1-fold, but the IPTG-induced DcHsp17.7 expression increased the ADH level by 1.7-fold.In scanning electron microscopy, the two transformed cell lines with high levels of ADH accumulation, ADH_Hsp70HR and ADH_Hsp17.7P,showed filamentation, which is characteristic of retarded cell division.Our results showed that recombinant protein yield depends on the type and co-expression pattern of the Hsp chaperone.Filamentation can be advantageous for enhanced production of some recombinant proteins in E. coli.