My recombinant protein is transmembrane protein that cloned into pET-22b that contain PelB signaling peptide at the N-terminal. 

I need to express recombinant protein in a secretion form that secreted to periplasmic space of host.

I try to express at 25'C with 0.1mM IPTG in E. coli BL21(DE3) but it still express in inclusion bodies.

I think this protein toxic to host or not? 

I should change host from BL21(DE3) to Lemo21(DE3)?

Thank you for your suggestion