5c21

Publication Abstract from PubMed

The protein toxin HlyA of Escherichia coli is exported without a periplasmic intermediate by the type I secretion system (T1SS). The T1SS is composed of an inner membrane ABC transporter HlyB, an outer-membrane channel protein TolC, and a membrane fusion protein HlyD. However, the assembly of the T1SS remains to be elucidated. In this study, we determine the crystal structure of a part of the C-terminal periplasmic domain of HlyD. The long alpha-helical domain consisting of three alpha helices and a lipoyl domain was identified in the crystal structure. Based on the HlyD structure, we modeled the hexameric assembly of HlyD with a long alpha-helical barrel, which formed a complex with TolC in an intermeshing cogwheel-to-cogwheel manner, as observed in tripartite RND-type drug efflux pumps. These observations provide a structural blueprint for understanding the type I secretion system in pathogenic Gram-negative bacteria.

Crystal Structure of a Soluble Fragment of the Membrane Fusion Protein HlyD in a Type I Secretion System of Gram-Negative Bacteria.,Kim JS, Song S, Lee M, Lee S, Lee K, Ha NC Structure. 2016 Jan 22. pii: S0969-2126(16)00005-8. doi:, 10.1016/j.str.2015.12.012. PMID:26833388^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.