Xinglong Wang , Kangjie Xu , Haoran Fu , Qiming Chen , Beichen Zhao , Xinyi Zhao , Jingwen Zhou
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引用次数: 0
Abstract
Streptomyces mobaraenesis transglutaminase (smTG) can be used for site-specific labeling of proteins with chemical groups. Here, we explored the use of modified smTG for the biosynthesis of nanobody-fluorophore conjugates (NFC). smTG catalyzes the conjugation of acyl donors containing glutamine with lysine-containing acceptors, which can lead to non-specific cross-linking. To achieve precise site-specific labeling, we employed molecular docking and virtual mutagenesis to redesign the enzyme's substrate specificity towards the peptide GGGGQR, a non-preferred acyl donor for smTG. Starting with a thermostable and highly active smTG variant (TGm2), we identified that single mutations G250H and Y278E significantly enhanced activity against GGGGQR, increasing it by 41 % and 1.13-fold, respectively. Notably, the Y278E mutation dramatically shifted the enzyme's substrate preference, with the activity ratio against GGGGQR versus the standard substrate CBZ-Gln-Gly rising from 0.05 to 0.93. In case studies, we used nanobodies 1C12 and 7D12 as labeling targets, catalyzing their conjugation with a synthetic fluorophore via smTG variants. Nanobodies fused with GGGGQR were successfully site-specifically labeled by TGm2-Y278E, in contrast to non-specific labeling observed with other variants. These results suggest that engineering smTG for site-specific labeling is a promising approach for the biosynthesis of antibody-drug conjugates.
期刊介绍:
Synthetic and Systems Biotechnology aims to promote the communication of original research in synthetic and systems biology, with strong emphasis on applications towards biotechnology. This journal is a quarterly peer-reviewed journal led by Editor-in-Chief Lixin Zhang. The journal publishes high-quality research; focusing on integrative approaches to enable the understanding and design of biological systems, and research to develop the application of systems and synthetic biology to natural systems. This journal will publish Articles, Short notes, Methods, Mini Reviews, Commentary and Conference reviews.