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Trimethylation of the R5 Silica‐Precipitating Peptide Increases Silica Particle Size by Redirecting Orthosilicate Binding
Author(s) -
Buckle Erika L.,
Sampath Janani,
Michael Nina,
Whedon Samuel D.,
Leonen Calvin J. A.,
Pfaendtner Jim,
Drobny Gary P.,
Chatterjee Champak
Publication year - 2020
Publication title -
chembiochem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.05
H-Index - 126
eISSN - 1439-7633
pISSN - 1439-4227
DOI - 10.1002/cbic.202000264
Subject(s) - tetraethyl orthosilicate , peptide , orthosilicate , lysine , chemistry , side chain , aqueous solution , biophysics , biochemistry , chemical engineering , stereochemistry , crystallography , amino acid , organic chemistry , biology , polymer , engineering
The unmodified R5 peptide from silaffin in the diatom Cylindrotheca fusiformis rapidly precipitates silica particles from neutral aqueous solutions of orthosilicic acid. A range of post‐translational modifications found in R5 contribute toward tailoring silica morphologies in a species‐specific manner. We investigated the specific effect of R5 lysine side‐chain trimethylation, which adds permanent positive charges, on silica particle formation. Our studies revealed that a doubly trimethylated R5K3,4me3 peptide has reduced maximum activity yet, surprisingly, generates larger silica particles. Molecular dynamics simulations of R5K3,4me3 binding by the precursor orthosilicate anion revealed that orthosilicate preferentially associates with unmodified lysine side‐chain amines and the peptide N terminus. Thus, larger silica particles arise from reduced orthosilicate association with trimethylated lysine side chains and their redirection to the N terminus of the R5 peptide.