Biology subjects

Wakabayashi, R.

Publications and source records attributed to Wakabayashi, R..

2 recordsLinked to original sources

bioRxiv2024

Exploring the molecular structure of lipids in the design of artificial lipidated antifungal proteins

Fungal infections have been a concern for decades, yet effective and approved antifungal agents are limited. We recently developed a potential method to enhance the antifungal activity of a small chitin-binding domain (LysM) from Pteris ryukyuensis chitinase A (PrChiA) by the site-specific introduction of a palmitoyl (C16) group catalyzed by microbial transglutaminase (MTG). Herein, we attempted the conjugation of a series of lipid-peptide substrates with LysM genetically fused with a C-terminal MTG-reactive Q-tag (LysM-Q) to yield LysM-lipid conjugates (LysM-lipids) with different lengths (LysM-C12, -C14, and -C16) and different numbers of alkyl chains [LysM-(C12)2, - (C14)2, and -(C16)2]. The enzymatic conjugation proceeded smoothly for all LysM-lipids, except for LysM-(C16)2 because of the low aqueous dispersibility of the hydrophobic (C16)2 lipid-peptide substrate. The combination of amphotericin B (AmB) with LysM-C14 or LysM-C16 exhibited the highest antifungal performance against Trichoderma viride whereas alterations in the number of alkyl chains were not effective in enhancing the antifungal activity of the LysM-lipids. Fluorescent microscopic analysis showed that the fungal cell wall was stained with C14- and C16-modified LysM-muGFP fusion proteins when combined with AmB, suggesting a synergistic action of AmB and LysM-lipids with a suitable lipid length. All LysM-lipids showed minimum cytotoxicity toward mammalian cells, suggesting that LysM-lipids could be a safe additive in the development of new antifungal formulations.

bioengineering↗

bioRxiv2023

Engineered Active Zymogen of Microbial Transglutaminase

Microbial transglutaminase (MTG) has shown to be a powerful biocatalytic glue for site-specific crosslinking of a range of biomolecules and synthetic molecules, those handled with an MTG-reactive moiety. The preparation of active recombinant MTG requires the posttranslational proteolytic digestion of propeptide working as an intramolecular chaperon to assist the correct folding of MTG zymogen (MTGz) in the biosynthesis. Herein, we propose an engineered active zymogen of MTG (EzMTG) that is expressed as soluble form in the host E. coli cytosol and exhibits the cross-linking activity without limited proteolysis. Based on the 3D structure of MTGz and serendipitous findings, saturated mutagenesis of K10 or Y12 in propeptide domain leads to generate several active MTGz mutants. In particular, K10D/Y12G mutant exhibited the catalytic activity comparable with a mature form. However, the expression level was low possibly due to the reduction of chaperone activity and/or the promiscuous substrate specificity of MTG, which is potentially harmful to the host cells. By contrast, soluble K10R/Y12A mutant is expressed in the cytosol of host E. coli and exhibited unique substrate-dependent reactivity toward peptidyl substrates. The quantitative analysis of the binding affinity of mutated propeptide to the active site suggested the trade-off relationship of EzMTGs between the binding affinity and the catalytic activity. Our proof-of-concept study provides insights into the design of a new biocatalyst by using the zymogen as a scaffold and will convey a potential route to the high-throughput screening of MTG mutants for bioconjugation applications.

biochemistry↗