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Infect Immun. 2017 Feb 23;85(3). pii: e00872-16. doi: 10.1128/IAI.00872-16. Print 2017 Mar.

Interaction between SWP9 and Polar Tube Proteins of the Microsporidian Nosema bombycis and Function of SWP9 as a Scaffolding Protein Contribute to Polar Tube Tethering to the Spore Wall.

Yang D1,2,3, Pan L4, Peng P1,5, Dang X6, Li C1,5, Li T1,5, Long M1,5, Chen J1,5, Wu Y1,5, Du H1,5, Luo B1,5, Song Y1,5, Tian R1,5, Luo J1,3,5, Zhou Z1,6,5, Pan G7,5.

Author information

1
State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, People's Republic of China.
2
International Academy of Targeted Therapeutics and Innovation, Chongqing Key Laboratory of Kinase Modulators as Innovative Medicine, Chongqing Engineering Laboratory of Targeted and Innovative Therapeutics, Chongqing University of Arts and Sciences, Chongqing, People's Republic of China.
3
College of Forestry and Life Sciences, Chongqing University of Arts and Sciences, Chongqing, People's Republic of China.
4
Foreign Language Department, Chongqing Water Resources and Electric Engineering College, Chongqing, People's Republic of China.
5
Key Laboratory for Sericulture Functional Genomics and Biotechnology of Agricultural Ministry, Southwest University, Chongqing, People's Republic of China.
6
College of Life Sciences, Chongqing Normal University, Chongqing, People's Republic of China.
7
State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing, People's Republic of China gqpan@swu.edu.cn.

Abstract

All microsporidia possess a unique, highly specialized invasion mechanism that involves the polar tube and spore wall. The interaction between spore wall proteins (SWPs) and polar tube proteins (PTPs) in the formation, arrangement, orderly orientation, and function of the polar tube and spore wall remains to be determined. This study was undertaken to examine the protein interactions of Nosema bombycis SWP7 (NbSWP7), NbSWP9, and PTPs. Coimmunoprecipitation, liquid chromatography-tandem mass spectrometry (LC-MS/MS), and yeast two-hybrid data demonstrated that NbSWP9, but not NbSWP7, interacts with NbPTP1 and NbPTP2. Furthermore, immunoelectron microscopy (IEM) showed that NbSWP9 was localized mainly in the developing polar tube of sporoblasts, while NbSWP7 was found randomly in the cytoplasm. However, both NbSWP9 and NbSWP7 were located in the polar tube and spore wall of N. bombycis mature spores. The reason why NbSWP7 was localized to the polar tube may be due to the interaction between NbSWP9 and NbSWP7. Interestingly, the majority of NbSWP9, but not NbSWP7, accumulated in the beginning part of the extruded polar tube and the ruptured spore wall called the anchoring disk (AD) when the mature spores germinated under weak-alkaline environmental stimulation. Additionally, anti-NbSWP9 antibody reduced spore germination in a dose-dependent manner. In conclusion, our study further confirmed that NbSWP9 is a scaffolding protein that not only anchors and holds the polar tube but also tethers the polar tube to the spore wall.

KEYWORDS:

germination; interaction; microsporidia; polar tube protein; spore wall protein

PMID:
28031263
PMCID:
PMC5328477
DOI:
10.1128/IAI.00872-16
[Indexed for MEDLINE]
Free PMC Article

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