Difference between revisions of "Part:BBa K554008"

Revision as of 09:30, 20 October 2020

Hemolysin D - HlyD

HlyD is part of the hemolysin secretion system ([http://2011.igem.org/Team:UNICAMP-EMSE_Brazil/Project#Device_3:_Secretion_system Device 3, Protein Secretion System]), very important to export the proteins produced inside bacteria and that must act in targets outside (such as IL-12 and IL-10). HlyD acts as a membrane fusion or adaptor protein, consisting of a short cytoplasmic domain at the N-terminus followed by a membrane anchor and a large periplasmic domain; it is believed to establish specific links between the outer and the inner membrane components of the system. This system is composed of 4 essential parts: the C-terminal signal sequence of alpha-hemolysin (HlyA, which will be linked to the export target protein), the two specific translocator proteins HlyB and HlyD and the outer membrane protein [BBa_K554009 TolC].

Sequence and Features

Usage and Biology

You can see a representation of this device acting in the schema below: HlyB gene and product are shown as a symbolic cilinder in orange.

Representation of device 3, the protein secretion system, in a Jedi bacteria that contains Device 1 (Adrenaline sensor/IL-12 producer). To export a protein, the bacteria must have the HlyD, HlyB and TolC proteins and the target protein must have a signal sequence (HlyA tail). In this case, the target protein to be secreted is IL-12.

A more realistic schema of ABC transport system is shown below:

MIT MAHE 2020

Useage and Biology HlyD is part of the hemolysin secretion system, very important to export the proteins produced inside bacteria and that must act in targets outside. HlyD acts as a membrane fusion or adaptor protein, consisting of a short cytoplasmic domain at the N-terminus followed by a membrane anchor and a large periplasmic domain; it is believed to establish specific links between the outer and the inner membrane components of the system. As part of its molecular function, it acts as a toxin transmembrane transporter. While, the biological functions include hemolysis in other organism, protein secretion and toxin transport.

HlyD forms a continuous channel by docking to the outer-membrane protein, TolC. This ternary complex spans the entire cell envelope including two membranes and the periplasm (Thanabalu et al., 1998). HylD is predicted to have a small N-terminal cytoplasmic tail, a transmembrane region, and a C-terminal large periplasmic domain, whose three-dimensional structure remains mostly unknown (Balakrishnan et al., 2001).

In a recent study the sensitivity range and linearity of amplification of qPCR was determined using primers and a probe targeting hlyD. The primary outcome of this study showed the successful development of an efficient qPCR assay based on hlyD, a gene that is absent in most commensal E. coli but present in most Uropathogenic Escherichia coli (UPEC), and particularly pyelonephritis-causing UPEC strains (Michelle N. Chamoun et al., 2018).

References

Thanabalu, T., Koronakis, E., Hughes, C., & Koronakis, V. (1998). Substrate-induced assembly of a contiguous channel for protein export from E. coli: reversible bridging of an inner-membrane translocase to an outer membrane exit pore. The EMBO journal, 17(22), 6487–6496. https://doi.org/10.1093/emboj/17.22.6487

Balakrishnan, L., Hughes, C., & Koronakis, V. (2001). Substrate-triggered recruitment of the TolC channel-tunnel during type I export of hemolysin by Escherichia coli. Journal of molecular biology, 313(3), 501–510. https://doi.org/10.1006/jmbi.2001.5038

Chamoun, M. N., Sullivan, M. J., & Ulett, G. C. (2018). Quantification of bacteriuria caused by Hemolysin-positive Escherichia coli in human and mouse urine using quantitative polymerase chain reaction (qPCR) targeting hlyD. Journal of microbiological methods, 152, 173–178. https://doi.org/10.1016/j.mimet.2018.08.004

Structure:

https://www.rcsb.org/structure/5C21