Eye patches: Protein assembly of index-gradient squid lenses.

Cai J, Townsend JP, Dodson TC, Heiney PA, Sweeney AM, Science 2017 Aug 11;357(6351):564-569 PubMed

SASDCQ5 – SAXS on intact Doryteuthis squid lens 100% layer

S-crystallin, Q25367_DOROP
MWexperimental 50 kDa
MWexpected 55 kDa
log I(s)
S-crystallin, Q25367_DOROP small angle scattering data  s, nm-1
S-crystallin, Q25367_DOROP Kratky plot 0 3 sRg

Fits and models

log I(s)
 s, nm-1
S-crystallin, Q25367_DOROP DAMMIF model
This dataset is SAXS characterization of the peripheral region (tissue from radial positions of 100%–80% of the total lens radius) of the intact Doryteuthis squid eye lens tissue. The lens contains about 40 unique S-crystallins isoforms that vary in molecular weight due to length variation in a disordered region encoded in the central exon of the coding sequence such that loops form protruding from the folded protein. S-crystallins are dimeric and globular, such that each dimer has two of these disordered loops, which form linking structures between particles in the system. Because the proteins link to form extended materials, even at very low concentration, the parameter Rg does not apply here. Similarly, because this is a measurement of intact biological tissue, there is no experimental buffer per se to subtract, and accordingly, raw data without buffer subtraction are reported here. The pair-distance distribution function (p(r)) was calculated based on unsubtracted data (refer to the full entry zip archive for the p(r) profile). The full set of sequences describing the protein polydispersity in this system is available at GenBank BioProject PRJNA386124. Synchrotron SAXS data were collected on the X9A beam line of the National Synchrotron Light Source (NSLS; Brookhaven, NY, USA) using a 20Hz Pilatus 300K detector at a wavelength of λ = 0.103318 nm (I(s) vs s, where s = 4πsinθ/λ and 2θ is the scattering angle). The sample measurement (1 x 60 s exposure) was performed at at 10°C.

S-crystallin, Q25367_DOROP (S-crystallin, Q25367)
Mol. type   Protein
Organism   Doryteuthis pealeii
Olig. state   Dimer
Mon. MW   27.3 kDa
UniProt   Q25367_DOR (1-232)
Sequence   FASTA