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Lv Q, Hong L, Qi L, Chen Y, Xie Z, Liao H, Li C, Li T, Meng X, Chen J, Bao J, Wei J, Han B, Shen Q, Weiss LM, Zhou Z, Long M, Pan G. Microsporidia dressing up: the spore polaroplast transport through the polar tube and transformation into the sporoplasm membrane. mBio 2024; 15:e0274923. [PMID: 38193684 PMCID: PMC10865828 DOI: 10.1128/mbio.02749-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Accepted: 11/30/2023] [Indexed: 01/10/2024] Open
Abstract
Microsporidia are obligate intracellular parasites that infect a wide variety of hosts including humans. Microsporidian spores possess a unique, highly specialized invasion apparatus involving the polar filament, polaroplast, and posterior vacuole. During spore germination, the polar filament is discharged out of the spore forming a hollow polar tube that transports the sporoplasm components including the nucleus into the host cell. Due to the complicated topological changes occurring in this process, the details of sporoplasm formation are not clear. Our data suggest that the limiting membrane of the nascent sporoplasm is formed by the polaroplast after microsporidian germination. Using electron microscopy and 1,1'-dioctadecyl-3,3,3',3' tetramethyl indocarbocyanine perchlorate staining, we describe that a large number of vesicles, nucleus, and other cytoplasm contents were transported out via the polar tube during spore germination, while the posterior vacuole and plasma membrane finally remained in the empty spore coat. Two Nosema bombycis sporoplasm surface proteins (NbTMP1 and NoboABCG1.1) were also found to localize in the region of the polaroplast and posterior vacuole in mature spores and in the discharged polar tube, which suggested that the polaroplast during transport through the polar tube became the limiting membrane of the sporoplasm. The analysis results of Golgi-tracker green and Golgi marker protein syntaxin 6 were also consistent with the model of the transported polaroplast derived from Golgi transformed into the nascent sporoplasm membrane.IMPORTANCEMicrosporidia, which are obligate intracellular pathogenic organisms, cause huge economic losses in agriculture and even threaten human health. The key to successful infection by the microsporidia is their unique invasion apparatus which includes the polar filament, polaroplast, and posterior vacuole. When the mature spore is activated to geminate, the polar filament uncoils and undergoes a rapid transition into the hollow polar tube that transports the sporoplasm components including the microsporidian nucleus into host cells. Details of the structural difference between the polar filament and polar tube, the process of cargo transport in extruded polar tube, and the formation of the sporoplasm membrane are still poorly understood. Herein, we verify that the polar filament evaginates to form the polar tube, which serves as a conduit for transporting the nucleus and other sporoplasm components. Furthermore, our results indicate that the transported polaroplast transforms into the sporoplasm membrane during spore germination. Our study provides new insights into the cargo transportation process of the polar tube and origin of the sporoplasm membrane, which provide important clarification of the microsporidian infection mechanism.
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Affiliation(s)
- Qing Lv
- State Key Laboratory of Resource Insects, Southwest University, Chongqing, China
- Chongqing Key Laboratory of Microsporidia Infection and Control, Southwest University, Chongqing, China
| | - Liuyi Hong
- State Key Laboratory of Resource Insects, Southwest University, Chongqing, China
- Chongqing Key Laboratory of Microsporidia Infection and Control, Southwest University, Chongqing, China
| | - Lei Qi
- Biomedical Research Center for Structural Analysis, Shandong University, Jinan, Shandong, China
| | - Yuqing Chen
- State Key Laboratory of Resource Insects, Southwest University, Chongqing, China
- Chongqing Key Laboratory of Microsporidia Infection and Control, Southwest University, Chongqing, China
| | - Zhengkai Xie
- State Key Laboratory of Resource Insects, Southwest University, Chongqing, China
- Chongqing Key Laboratory of Microsporidia Infection and Control, Southwest University, Chongqing, China
| | - Hongjie Liao
- State Key Laboratory of Resource Insects, Southwest University, Chongqing, China
- Chongqing Key Laboratory of Microsporidia Infection and Control, Southwest University, Chongqing, China
| | - Chunfeng Li
- State Key Laboratory of Resource Insects, Southwest University, Chongqing, China
- Chongqing Key Laboratory of Microsporidia Infection and Control, Southwest University, Chongqing, China
| | - Tian Li
- State Key Laboratory of Resource Insects, Southwest University, Chongqing, China
- Chongqing Key Laboratory of Microsporidia Infection and Control, Southwest University, Chongqing, China
| | - Xianzhi Meng
- State Key Laboratory of Resource Insects, Southwest University, Chongqing, China
- Chongqing Key Laboratory of Microsporidia Infection and Control, Southwest University, Chongqing, China
| | - Jie Chen
- State Key Laboratory of Resource Insects, Southwest University, Chongqing, China
- Chongqing Key Laboratory of Microsporidia Infection and Control, Southwest University, Chongqing, China
| | - Jialing Bao
- State Key Laboratory of Resource Insects, Southwest University, Chongqing, China
- Chongqing Key Laboratory of Microsporidia Infection and Control, Southwest University, Chongqing, China
| | - Junhong Wei
- State Key Laboratory of Resource Insects, Southwest University, Chongqing, China
- Chongqing Key Laboratory of Microsporidia Infection and Control, Southwest University, Chongqing, China
| | - Bing Han
- Department of Pathogenic Biology, School of Basic Medical Sciences, Shandong University, Jinan, Shandong, China
| | - Qingtao Shen
- School of Life Science, Southern University of Science and Technology, Shenzhen, Guangdong, China
| | - Louis M. Weiss
- Department of Pathology, Albert Einstein College of Medicine, New York, USA
| | - Zeyang Zhou
- State Key Laboratory of Resource Insects, Southwest University, Chongqing, China
- Chongqing Key Laboratory of Microsporidia Infection and Control, Southwest University, Chongqing, China
- College of Life Sciences, Chongqing Normal University, Chongqing, China
| | - Mengxian Long
- State Key Laboratory of Resource Insects, Southwest University, Chongqing, China
- Chongqing Key Laboratory of Microsporidia Infection and Control, Southwest University, Chongqing, China
| | - Guoqing Pan
- State Key Laboratory of Resource Insects, Southwest University, Chongqing, China
- Chongqing Key Laboratory of Microsporidia Infection and Control, Southwest University, Chongqing, China
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