Structural comparison of the transport units of type V secretion systems

Abstract

Pathogenic gram-negative bacteria have evolved several secretion mechanisms to translocate adhesins, enzymes, toxins, and other virulence factors across the inner and outer membranes. Currently, eight different secretion systems, type I-type VIII (T1SS-T8SS) plus the chaperone-usher (CU) pathway, have been identified, which act in one-step or two-step mechanisms to traverse both membrane barriers. The type V secretion system (T5SS) is dependent first on the Sec translocon within the inner membrane. The periplasmic intermediates are then secreted through aqueous pores formed by β-barrels in the outer membrane. Until now, transport across the outer membrane has not been understood on a molecular level. With respect to special characteristics revealed by crystal structure analysis, bioinformatic and biochemical data, five subgroups of T5SS were defined. Here, we compare the transport moieties of members of four subgroups based on X-ray crystal structures. For the fifth subgroup, which was identified only recently, no structures have thus far been reported. We also discuss different models for the translocation process across the outer membrane with respect to recent findings.

Co-expression of active human cytochrome P450 1A2 and cytochrome P450 reductase on the cell surface of Escherichia coli

“…It is controversially discussed whether a partially folded passenger can be translocated across the outer membrane. Two mechanisms for translocation—the hairpin model and the Omp85 model—have been proposed whereas only the latter would be compatible with partial protein folding [ 10 ]. We observed that heme derived from cells is way more effective for increasing CYP activity than externally added heme.…”

“…As a biotechnological tool for surface display of recombinant proteins so-called autotransporters have been widely employed [ 9 ]. They are derived from natural outer membrane proteins in gram-negative bacteria and their translocation mechanism and structure have been intensively studied [ 10 – 14 ]. The technique has been successfully applied for the display of a variety of enzymes such as nitrilase [ 15 ], lipase and foldase [ 16 ], protein kinase CK2 [ 17 ] as well as other proteins like V HH antibody fragments [ 18 ], affibodies [ 19 ] and peptides [ 20 ].…”

Highlight: NRW Research School BioStruct – Biological Structures in Molecular Medicine and Biotechnology

“…The reviews by Lenders et al (2013) and Gawarzewski et al (2013) summarize structural and functional data that provide molecular insights into the Type I and Type V secretion systems, respectively. Sch ü nke and Stoldt (2013) describe structural insights about cyclic nucleotide-binding induced conformational changes in cyclic nucleotidebinding domains (CNBDs) and their potential coupling with channel gating.…”

Diversity of secretion systems associated with virulence characteristics of the classical bordetellae

“…The T4SS has been shown to transport nucleic acids in addition to complex proteins (Christie et al, , 2014. T5SSs can be divided into five subclasses (a-e): the T5aSS is an autotransporter (AT), the T5bSS is a two-partner secretion (TPS) system, the T5cSS is the trimeric AT, the T5dSS is a fusion between AT and TPS, and finally the T5eSS is the inverted AT (Gawarzewski et al, 2013;Leo et al, 2012). They have been shown to be required for virulence in Haemophilus influenzae, Yersinia enterocolitica, Neisseria gonorrhoeae, Helicobacter pylori and Bordetella pertussis (Bernstein, 2007;Dautin & Bernstein, 2007;Henderson et al, 2004;Jacob-Dubuisson et al, 2004;Marr et al, 2008;Noofeli et al, 2011).…”