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. 2017 Jun 8;8:962. doi: 10.3389/fmicb.2017.00962

FIGURE 1.

FIGURE 1

lmrB in Streptococcus mutans UA159 encoded an efflux transporter. (A) Domain architecture of LmrB. The conserved domain in the N-terminus of LmrB was found by searching CDD database on the National Center for Biotechnology Information (NCBI) website. The protein contains 13 transmembrane (TM) regions, a conserved sugar transporter domain and a MFS motif. (B) Separation of total cell lysate and isolated membrane proteins from Escherichia coli transformed with pET28a-lmrB with His-tag using SDS–PAGE profile. Lane 1: total protein of control group (E. coli cells transformed with pET28a); lane 2: membrane protein of E. coli transformed with pET28a–lmrB-His-tag; lanes 3 and 5: total protein of E. coli transformed with pET28a–lmrB-His-tag; lane 4: membrane protein of control group (E. coli cells transformed with pET28a). (C) Proteins were transferred to nitrocellulose membrane and probed with anti-His tag. The Western-blot analysis further confirmed that the recombinant protein was integrated into the membrane of E. coli. (D) The 3D model of LmrB using E. coli YajR transporter as template. (E) Fluorometric EtBr efflux assay. E. coli with pET28a-lmrB exhibited higher efflux activity characterized by the low fluorescence intensity.