Difference between revisions of "Part:BBa K638001"

Revision as of 12:11, 28 September 2020

Reflectin A1 from Loligo

This is the coding region for [http://www.ncbi.nlm.nih.gov/nuccore/FJ824804.1 Reflectin A1 protein] (originally found in the mantle of squid Loligo pealeii) codon optimised for E. coli. [http://2011.igem.org/Team:Cambridge Cambridge 2011] overexpressed it for purification using the his-tagged generator BBa_K638202 . We also exported it as a TorA fusion.

Usage and Biology

In the squid this protein is believed to self assemble with membranes to form iridophore platelets - stacks of protein ultrastructure evenly spaced to form a Bragg stack. This creates living structural colour from thin film interference effects. In L. pealeii reflectins are phosphorylated, with [http://www.ncbi.nlm.nih.gov/pubmed/19776150 changes in phosphorylation status correlating with changes in tissue colour]. Read more about [http://2011.igem.org/Team:Cambridge/Project/Background the background to this protein].

Reflectin Proteins

Many cephalopods (octopuses, squids, cuttlefish, etc.) demonstrate camouflage capabilities by adaptive transparency. Some chalepods can even vanish from the environment by performing these capabilities. These animals can change the optical properties of their skin, how their skin transmits, absorbs, and reflects light [3]. Reflectivity in these animal tissues is achieved by stacking flat, insoluble, structural platelets by alternating layers of high and low refractive index in iridocytes [4]. This alternate arrangement, called a Bragg reflector, creates a thin-film interference pattern which is the reason for reflection of incident light from the tissue [3]. In aquatic animals, reflector platelets generally consist of purine crystals, particularly guanine and hypoxanthine. However, cephalopod reflector platelets contain reflectin proteins instead of these purine crystals. Reflectin proteins found in cephalopods are responsible for transparency abilities by employing structural coloration and iridescence [1, 2].

Optical characterization of these proteins is an important work for studies using reflectin proteins. However, it is hard to characterize the refractive index of these proteins since there are multiple Bragg stacks with unknown variation in spacings, refractive indices and orientations in a typical tissue of a chalepod. Ghoshal et al (2014) employed a microspectroscopy procedure to investigate these properties. They found a progressively higher refractive index from 1.33 to 1.43 from the same Bragg stack as they immersed these Bragg stacks in solutions of different reflectivities. [1] Junko Ogawa et al. (2020) Genetic manipulation of the optical refractive index in living cells https://doi.org/10.1101/2020.07.09.196436 [2] Atrouli Chatterjee et al. (2020) Cephalopod-inspired optical engineering of human cells https://doi.org/10.1038/s41467-020-16151-6 [3] Wendy J. Crookes et al. (2004) Reflectins: The Unusual Proteins of Squid Reflective Tissues https://doi.org/10.1126/science.1091288 [4] Amitabh Ghoshal et al. (2014) Experimental determination of refractive index of condensed reflectin in squid iridocytes http://dx.doi.org/10.1098/rsif.2014.0106

Safety

The protein coding sequence for reflectin originally came from cells of an edible squid. There have been no reported safety issues for reflectins, so we do not anticipate the need for extra precautions when using this BioBrick part. See our [http://2011.igem.org/Team:Cambridge/Safety safety page] for more information.

Sequence and Features