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mosquito

 

The Mosquito Net (1912) by John Singer Sargent. Licensed under Public Domain via Wikimedia Commons

The Mosquito Net (1912) by John Singer Sargent. Licensed under Public Domain via Wikimedia Commons

 

We all know how pesky mosquitoes can be. Did you know that the ability of a mosquito to find a suitable host to feed is due to thermotaxis? This behavior, being attracted/repelled due to high/low temperature, is seen in other organisms as well such as Drosophila melanogaster and Caenorhabditis elegans. 

However, the behaviour is more pronounced among blood-feeding pests (kissing bugs, bedbugs, Ticks, and mosquitoes including Aedes aegypti). Aedes aegypti is a vector for many flaviviral diseases (Dengue fever, Yellow fever, etc.) Until now, it was well established that thermotaxis requires specific thermosensors that activate the sensory signals for a subsequent flight response in a mosquito. However, how exactly they function was not resolved.

ResearchBlogging.orgIn a recent paper by Corfas and Vosshall [1] describe the use of zinc-finger nuclease-mediated genome editing method to identify the role of two receptors TRPA1 and GR19 in Aedes aegypti‘s attraction to heat. It was found that these receptors help the mosquito to identify the host for feeding (in the temperature range of 43-50 deg Celcius), however they avoid surfaces that exhibit above 50 deg Celcius. [Read the recent editorial on genome editing in Genome Biology]

The sequence (923 residues long) of this receptor (Uniprot id: Q0IFQ4) has at least five transmembrane regions that are approximately 20-25 residues long. A cursory glance at homologous sequences shows that it shares 37% sequence identity with the a de novo designed protein (PDB id:2xeh).

The homology modeled structure showing coiled coil region (residues 189-338). Although, the eLife paper does not talk about structure, I felt that this paper deserves a mention here. The reason is the structural biology/bioinformatics possibilities with this novel target. It is a suitable target for designing inhibitors that would potentially act as mosquito repellents.

Also, combined with the method described in my previous post on mutating transmembrane proteins as a method of making them crystallize, I guess the 3D structure of this important protein will come to light sooner!

Homology modeled region of TRPA1, from ModBase

Homology modeled region of TRPA1 (189-338), from ModBase

 

References:

  1. Corfas RA, & Vosshall LB (2015). The cation channel TRPA1 tunes mosquito thermotaxis to host temperatures. eLife, 4 PMID: 26670734
  2. Greppi, Chloe and Budelli, Gonzalo and Garrity, Paul A (2015). Some like it hot, but not too hot. eLife, 4
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