MtvR affects E. coli Hfq translation.

(A) Western blot analysis of the levels of the 6×His-tagged Hfq_Ec protein in cells of the E. coli Δhfq mutant expressing only the tagged protein (left panel, Δhfq/phfq), or also expressing the MtvR transcript (Right panel, Δhfq/phfq+pMtvR). The GroEL levels were used as loading control. (B) β-galactosidase relative activity in cells of the E. coli strains WT (black bars), WT expressing MtvR (+pMtvR, white bars), or WT with the empty vector (pMLBAD, grey bars), harboring the hfq_Ec 5′-UTR-LacZ fusion (p_hfq-LacZ). C) β-galactosidase activity of the indicated E. coli strains, grown in solid LB media, supplemented with X-Gal and 0.1% L-arabinose. The WT strain transformed with pMLBAD was used as control.