Site-Specific Reversible Protein and Peptide Modification: Transglutaminase-Catalyzed Glutamine Conjugation and Bioorthogonal Light-Mediated Removal
BIOCONJUGATE CHEMISTRY
Authors: Moulton, Kevin R.; Sadiki, Amissi; Koleva, Bilyana N.; Ombelets, Lincoln J.; Tran, Tina H.; Liu, Shanshan; Wang, Bryan; Chen, Hongyan; Micheloni, Emily; Beuning, Penny J.; O'Doherty, George A.; Zhou, Zhaohui Sunny
Abstract
Dynamic photoswitches in proteins that impart spatial and temporal control are important to manipulate and study biotic and abiotic processes. Nonetheless, approaches to install these switches into proteins site-specifically are limited. Herein we describe a novel site-specific method to generate photoremovable protein conjugates. Amine-containing chromophores (e.g., venerable o-nitrobenzyl and less-explored o-nitrophenylethyl groups) were incorporated via transamidation into a glutamine side chain of alpha-gliadin, LCMV, and TAT peptides, as well as beta-casein and UmuD proteins by transglutaminase (TGase, EC 2.3.2.13). Subsequently, photolysis regenerated the native peptides and proteins. When this modification leads to the reduction or abolishment of certain activities, the process is referred to as caging, as in the case for E. coli polymerase manager protein UmuD. Importantly, this method is simple, robust, and easily adaptable, e.g., all components are commercially available.
Development of the GlutEnSeq capture system for sequencing gluten gene families in hexaploid bread wheat with deletions or mutations induced by gamma-irradiation or CRISPR/Cas9
JOURNAL OF CEREAL SCIENCE
Authors: Jouanin, Aurelie; Borm, Theo; Boyd, Lesley A.; Cockram, James; Leigh, Fiona; Santos, Bruno A. C. M.; Visser, Richard G. F.; Smulders, Marinus J. M.
Abstract
We developed an in-solution gluten exome capture system called GlutEnSeq (Gluten gene Enrichment and Sequencing), covering the sequence variation of thousands of prolamin genes from various Triticeae species and cultivars. We assessed the efficacy of this capture system in hexaploid wheat (Triticum aestivum L.) using Illumina sequencing. On-target regions were determined based on the Chinese Spring (CS) reference genome sequence. Gluten gene sequences were generally enriched around 10,000-fold. The loss of gluten genes in CS deletion line 1BS-19/6DS-4 was detected as absence of gluten gene coverage on chromosomes 1B and Un (containing the Unmapped alpha-gliadin genes of chromosome 6D). Two gamma-irradiated lines of cultivar Paragon, shown to be affected in their gliadin protein profile, were found to contain homozygous deletions for the alpha-gliadins on 6A and the gamma-gliadins on 1B. Four Fielder CRISPR/Cas9 gliadin gene-edited lines revealed homozygous deletions of the gamma-gliadins on 1B and heterozygous deletions for the alpha-gliadins on 6A. We also detected a decrease of gluten gene coverage within some gluten genes. The bioinformatics pipeline developed here will be further optimised to enable characterisation of small indels within individual gluten genes, in order to fully analyse CRISPR/Cas9 mutant lines for their decrease in immunogenicity for Coeliac patients.