Lipopolysaccharide (LPS) is essential for most Gram-negative bacteria and has crucial roles in protection of the bacteria from harsh environments and toxic compounds, including antibiotics. This family includes members such as LPTD found in Shigella flexneri and Yersinia pestis. Structural analysis indicates that LptD forms a novel 26-stranded beta-barrel. It interacts with LPTE where LptE adopts a roll-like structure located inside the barrel of LptD. The LPS translocon LptD is unable to fold properly in the absence of LptE and the two proteins form a unique barrel and plug architecture for LPS transport and insertion [1] [2]. LptD is an essential outer membrane protein that mediates the final transport of lipopolysaccharide (LPS) to outer leaflet. It has been suggested that LptD is a promising target for the development of effective vaccines and antibody-based therapies to control Vibrio infection [3].

1: Structural basis for outer membrane lipopolysaccharide insertion. Dong H, Xiang Q, Gu Y, Wang Z, Paterson NG, Stansfeld PJ, He C, Zhang Y, Wang W, Dong C; Nature. 2014;511:52-56. PMID:24990744

2: Structural and Functional Characterization of the LPS Transporter LptDE from Gram-Negative Pathogens. Botos I, Majdalani N, Mayclin SJ, McCarthy JG, Lundquist K, Wojtowicz D, Barnard TJ, Gumbart JC, Buchanan SK; Structure. 2016;24:965-976. PMID:27161977

3: LptD is a promising vaccine antigen and potential immunotherapeutic target for protection against Vibrio species infection. Zha Z, Li C, Li W, Ye Z, Pan J; Sci Rep. 2016;6:38577. PMID:27922123