This study investigated the involvement of Conserve d inner membrane protein (YcbC) in the regulation o f Enterobacterial Common Antigen (ECA) synthesis oper on and penicillin-binding protein (PBP1b) transcrip tion and thus in thecell wall assembly of Escherichia coli. WT cells and ∆ elyC, ∆ mrcB and ∆ rfE mutants were grown in LB medium. Cells were collected and RNA extraction and purification was achieved. Thereafter, transcripti onal analysis by RT-PCR was performed on genes ycbC enco ded for Polypeptide conserved inner membrane protei n, wecA,wzzE,wecB, rffH, rffT, wzyE and wecG genes enc oded for Enterobacterial Common Antigen (ECA) biosynthesis, colanic acid biosynthesis glycosyltra nsferase (wcaA) and undecaprenyl diphosphate syntha se (uppS) genes. Overexpression of ycbC and rffH, rffT, wzzE, wzyE and uppS genes was observed in WT cells grown at 22°C. Furthermore, ∆ elyC mutant grown at 37°C and 22°C revealed the ove rexpression of ECA biosynthesis genes (wecA, wzzE, wecB, rffH, rffT, wzyE, wecG), mrcB, wcaA gen es and the high expression of uppS gene compared to WT. Overexpression of ECA cluster, uppS and wcaA genes was also observed in ∆ mrcB. Furthermore, the absence of rfE gene displays the overexpression of uppS and mrcB g enes. Our results show the coordination between Ely C (YcbC) factor and ECA polysaccharide, peptidoglycan (PG) a nd colonic acid synthesis. These results confirm th e important role of YcbC protein in Gram-negative bacterial cel l wall assembly. So, the characterisation of new en velope biogenesis factors important for Gram-negative bact eria will broaden our understanding of the bacteria l cell envelope biogenesis and validate the new factors as antibacterial targets.