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Wang J, Hu H, Pang S, Yin X, Cao B, Huang J, Xu X, Weng Q, Hu Q. Destruxin A inhibits the hemocytin-mediated hemolymph immunity of host insects to facilitate Metarhizium infection. Cell Rep 2024; 43:113686. [PMID: 38219149 DOI: 10.1016/j.celrep.2024.113686] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Revised: 11/07/2023] [Accepted: 01/02/2024] [Indexed: 01/16/2024] Open
Abstract
Insects have an effective innate immune system to protect themselves against fungal invasion. Metarhizium employs a toxin-based strategy using a nonribosomal peptide called destruxin A (DA) to counteract the host immune response. However, the mechanism by which DA inhibits insect immunity is still unclear. Here, we identified 48 DA-binding proteins in silkworm hemolymph, with the binding affinity (KD) ranging from 2 to 420 μM. Among these proteins, hemocytin, an important immune factor, was determined to be the strongest DA-binding protein. DA binds to hemocytin and regulates its conformation in a multisite manner. Furthermore, DA exerts a significant inhibitory effect on hemocytin-mediated hemocyte aggregation. By disrupting the interaction between hemocytin, actin A3, and gelsolin, DA prevents the transformation of granules into vesicles in hemocytes. These vesicles are responsible for storing, maturing, and exocytosing hemocytin. Therefore, hemocytin secretion is reduced, and the formation of structures that promote aggregation in outer hemocytes is inhibited.
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Affiliation(s)
- Jingjing Wang
- College of Plant Protection, South China Agricultural University, Wushan RD483, Tianhe, Guangzhou, China; College of Horticulture, South China Agricultural University, Wushan RD483, Tianhe, Guangzhou, China
| | - Hongwang Hu
- College of Plant Protection, South China Agricultural University, Wushan RD483, Tianhe, Guangzhou, China
| | - Suyun Pang
- College of Plant Protection, South China Agricultural University, Wushan RD483, Tianhe, Guangzhou, China
| | - Xuyu Yin
- College of Plant Protection, South China Agricultural University, Wushan RD483, Tianhe, Guangzhou, China
| | - Bihao Cao
- College of Horticulture, South China Agricultural University, Wushan RD483, Tianhe, Guangzhou, China
| | - Jilei Huang
- Instrumental Analytical and Research Center, South China Agricultural University, Wushan RD483, Tianhe, Guangzhou, China
| | - Xiaoli Xu
- Instrumental Analytical and Research Center, South China Agricultural University, Wushan RD483, Tianhe, Guangzhou, China
| | - Qunfang Weng
- College of Plant Protection, South China Agricultural University, Wushan RD483, Tianhe, Guangzhou, China
| | - Qiongbo Hu
- College of Plant Protection, South China Agricultural University, Wushan RD483, Tianhe, Guangzhou, China.
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Hu H, Yin X, Pang S, Jiang Y, Weng Q, Hu Q, Wang J. Mechanism of destruxin a inhibits juvenile hormone binding protein transporting juvenile hormone to affect insect growth. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2023; 197:105654. [PMID: 38072529 DOI: 10.1016/j.pestbp.2023.105654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Revised: 09/22/2023] [Accepted: 10/17/2023] [Indexed: 12/18/2023]
Abstract
Destruxin A, a non-ribosomal peptide toxin produced by Metarhizium, exhibits potent insecticidal activity by targeting various tissues, organs, and cells of insects. Our previous research has revealed that DA possesses the ability to bind to multiple proteins. In this study, we aimed to identify the most sensitive binding proteins of DA and investigate the physiological processes in which DA regulated. Through RNAi technology, we screened 22 binding proteins of DA in silkworm hemolymph. Among them, the juvenile hormone binding protein (JHBP), a hormone transport protein crucial for growth and development regulation, exhibited the highest sensitivity to DA. Subsequent experiments demonstrated that DA could inhibit the body weight gain of silkworm larvae, accelerate the pupation occurrence, and modulate the content of free juvenile hormone (JH) in the hemolymph. We also observed that DA could induce conformational changes in both the JHBP and the JHBP-JH binding complex. Notably, at low dosage, DA influenced the binding of JHBP to JH, while at high dosage, it irreversibly affected the binding of JHBP to JH. Molecular docking and point-mutant experiments suggested that DA might affect the N-arm of JHBP, which is responsible for JH binding. Additionally, we discovered that JHBP is widely distributed in various tissues of the silkworm, including the epidermis, gut, fat body, Malpighian tubule, gonad, muscle, trachea, and hemocyte. This study provides novel insights into the insecticidal mechanism of DA and enhances our understanding of the pathogenic process of Metarhizium.
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Affiliation(s)
- Hongwang Hu
- College of Plant Protection, South China Agricultural University, Guangzhou 510642, China.
| | - Xuyu Yin
- College of Plant Protection, South China Agricultural University, Guangzhou 510642, China.
| | - Suyun Pang
- College of Plant Protection, South China Agricultural University, Guangzhou 510642, China.
| | - Yali Jiang
- College of Plant Protection, South China Agricultural University, Guangzhou 510642, China.
| | - Qunfang Weng
- College of Plant Protection, South China Agricultural University, Guangzhou 510642, China.
| | - Qiongbo Hu
- College of Plant Protection, South China Agricultural University, Guangzhou 510642, China.
| | - Jingjing Wang
- College of Plant Protection, South China Agricultural University, Guangzhou 510642, China; College of Horticulture, South China Agricultural University, Guangzhou 510642, China.
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