Designed by: Fazilet Guler   Group: iGEM11_FAGEM   (2011-07-19)

Reflectin1A from Cephalopod

Reflectin is a self-assembling protein that has the ability to reflect the sun light which depends on the thickness of the protein layer. Therefore, we thought that this ability could be used as a novel reporter for B.subtilis and E.coli.

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

[2] Atrouli Chatterjee et al. (2020) Cephalopod-inspired optical engineering of human cells

[3] Wendy J. Crookes et al. (2004) Reflectins: The Unusual Proteins of Squid Reflective Tissues

[4] Amitabh Ghoshal et al. (2014) Experimental determination of refractive index of condensed reflectin in squid iridocytes

Sequence and Features

Assembly Compatibility:
  • 10
  • 12
  • 21
  • 23
  • 25
  • 1000

Functional Parameters: Austin_UTexas

BBa_K541506 parameters

Burden Imposed by this Part:

Burden Value: -1.8 ± 1.2%

Burden is the percent reduction in the growth rate of E. coli cells transformed with a plasmid containing this BioBrick (± values are 95% confidence limits). This BioBrick did not exhibit a burden that was significantly greater than zero (i.e., it appears to have little to no impact on growth). Therefore, users can depend on this part to remain stable for many bacterial cell divisions and in large culture volumes. Refer to any one of the BBa_K3174002 - BBa_K3174007 pages for more information on the methods, an explanation of the sources of burden, and other conclusions from a large-scale measurement project conducted by the 2019 Austin_UTexas team.

This functional parameter was added by the 2020 Austin_UTexas team.