Synthesis of ureido thioglycosides as novel insect β‑N‑acetylhexosaminidase OfHex1 inhibitors

Molecular Design Strategy of Protein Isoform-Specific Fluorescent Probes by Considering Molecule in Its Entirety

Generally, different isoforms of proteins exert separate biological functions. However, due to similar structures and identical catalysis functions, distinguishing isoforms is challenging. Summarizing a molecular design strategy has great significance in developing a protein-specific fluorescent probe. Usually, recognition of a group was deemed to be the key to a protein isoform-specific response. However, some novel literature reported that fluorophore could play a vital role in the protein isoform-specific response. It means that any part of the fluorescent probe could affect the detected properties. In this work, we report the generation of the first probe to specifically recognize HexA(β-N-acetylhexosaminidase A), Hex-C4, by adjusting the length of the linker. Hex-C4 exhibits specific recognition of HexA both in vitro and in living cells. The integration of the fluorescent spectrum and the MD (molecular dynamics) results provide two factors for the molecular design of isoform-specific fluorescent probes. One is the interaction between tetraphenyl ethylene (AIE fluorogen) and amino acid residues, and the other is the interaction between amino acid residues and the binding group. In this work, a powerful tool to detect HexA in living cells is reported for the first time. Further, a workable molecular design strategy for protein isoform-specific fluorescent probes is summarized.

The Role of Chitooligosaccharidolytic β-N-Acetylglucosamindase in the Molting and Wing Development of the Silkworm Bombyx mori

The insect glycoside hydrolase family 20 β-N-acetylhexosaminidases (HEXs) are key enzymes involved in chitin degradation. In this study, nine HEX genes in Bombyx mori were identified by genome-wide analysis. Bioinformatic analysis based on the transcriptome database indicated that each gene had a distinct expression pattern. qRT-PCR was performed to detect the expression pattern of the chitooligosaccharidolytic β-N-acetylglucosaminidase (BmChiNAG). BmChiNAG was highly expressed in chitin-rich tissues, such as the epidermis. In the wing disc and epidermis, BmChiNAG has the highest expression level during the wandering stage. CRISPR/Cas9-mediated BmChiNAG deletion was used to study the function. In the BmChiNAG-knockout line, 39.2% of female heterozygotes had small and curly wings. The ultrastructure of a cross-section showed that the lack of BmChiNAG affected the stratification of the wing membrane and the formation of the correct wing vein structure. The molting process of the homozygotes was severely hindered during the larva to pupa transition. Epidermal sections showed that the endocuticle of the pupa was not degraded in the mutant. These results indicate that BmChiNAG is involved in chitin catabolism and plays an important role in the molting and wing development of the silkworm, which highlights the potential of BmChiNAG as a pest control target.

Discovery of Biphenyl-Sulfonamides as Novel β-N-Acetyl-d-Hexosaminidase Inhibitors via Structure-Based Virtual Screening

Novel insecticidal targets are always in demand due to the development of resistance. OfHex1, a β-N-acetyl-d-hexosaminidase identified in Ostrinia furnacalis (Asian corn borer), is involved in insect chitin catabolism and has proven an ideal target for insecticide development. In this study, structure-based virtual screening, structure simplification, and biological evaluation are used to show that compounds with a biphenyl-sulfonamide skeleton have great potential as OfHex1 inhibitors. Specifically, compounds 10k, 10u, and 10v have K_i values of 4.30, 3.72, and 4.56 μM, respectively, and thus, they are more potent than some reported nonglycosyl-based inhibitors such as phlegmacin B₁ (K_i = 26 μM), berberine (K_i = 12 μM), 2 (K_i = 11.2 μM), and 3 (K_i = 28.9 μM). Furthermore, inhibitory kinetic assessments reveal that the target compounds are competitive inhibitors with respect substrate, and based on toxicity predictions, most of them have potent drug properties. The obtained results indicate that the biphenyl-sulfonamide skeleton characterized by simple chemical structure, synthetic tractability, potent activity, and low toxicity has potential for further development in pest management targeting OfHex1.