A Switch Controlling Biomolecular Reconfigurability
Abstract
Major Goals: The major goal of this project was to combine biophysical and genetic engineering approaches to identify the molecular mechanisms by which the reflectin protein transduces neuronal signals to the precisely calibrated finely tuned control of color and brightness of light reflected from intracellular Bragg reflectors in specialized skin cells of squids. We also proposed to develop techniques to genetically couple reflectin to other, non-tunable proteins, and demonstrate that such linkage will allow extension of tunable control to the conjugated carrier proteins. Accomplishments: Reflectin A1 (henceforth referred to simply as reflectin unless otherwise specified) is a cationic, block copolymeric, initially disordered protein that mediates the neuronally triggered, osmotically mediated, dynamic fine-tuning of the color and brightness of light reflected from nanostructured Bragg reflectors in specialized skin cells of squids. Its structure consists of a peptide chain of ca. 350 amino acids, with 6 blocks of unique and highly conserved (essentially identical) sequence alterating with cationic linkers. In our ARO-supported research (1-17), we discovered that progressive charge-neutralization of reflectin - either by neurotransmitter-activated phosphorylation in vivo, or by pH-titration, genetic engineering or anionic screening of the purified recombinant protein in vitro - drives its condensation, folding and hierarchical assembly to form liquid-liquid phase-separated particles of precisely calibrated size exponentially proportional to the extent of charge-neutralization. This assembly triggers the osmotic efflux of water from the Bragg lamellae, shrinking their thickness and spacing, while increasing their refractive index contrast - thus dynamically tuning the color while simultaneously increasing the intensity of the reflected light.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 03, 2021
- Accession Number
- AD1205144
Entities
People
- Daniel E Morse
Organizations
- University of California, Santa Barbara