Identification and characterization a novel polar tube protein (NbPTP6) from the microsporidian Nosema bombycis

  • PDF / 3,838,401 Bytes
  • 9 Pages / 595.276 x 790.866 pts Page_size
  • 73 Downloads / 197 Views

DOWNLOAD

REPORT


Parasites & Vectors Open Access

RESEARCH

Identification and characterization a novel polar tube protein (NbPTP6) from the microsporidian Nosema bombycis Qing Lv1,2, Lijun Wang1,2, Youpeng Fan1,2, Xianzhi Meng1,2, Keke Liu1,2, Bingqian Zhou1,2, Jie Chen1,2, Guoqing Pan1,2*, Mengxian Long1,2* and Zeyang Zhou1,2,3

Abstract  Background:  Microsporidians are opportunistic pathogens with a wide range of hosts, including invertebrates, vertebrates and even humans. Microsporidians possess a highly specialized invasion structure, the polar tube. When spores encounter an appropriate environmental stimulation, the polar tube rapidly everts out of the spore, forming a 50–500 µm hollow tube that serves as a conduit for sporoplasm passage into host cells. The polar tube is mainly composed of polar tube proteins (PTPs). So far, five major polar tube proteins have been isolated from microsporidians. Nosema bombycis, the first identified microsporidian, infects the economically important insect silkworm and causes heavy financial loss to the sericulture industry annually. Results:  A novel polar tube protein of N. bombycis (NbPTP6) was identified. NbPTP6 was rich in histidine (H) and serine (S), which contained a signal peptide of 16 amino acids at the N-terminus. NbPTP6 also had 6 potential O-glycosylation sites and 1 potential N-glycosylation site. The sequence alignment analysis revealed that NbPTP6 was homologous with uncharacterized proteins from other microsporidians (Encephalitozoon cuniculi, E. hellem and N. ceranae). Additionally, the NbPTP6 gene was expressed in mature N. bombycis spores. Indirect immunofluorescence analysis (IFA) result showed that NbPTP6 is localized on the whole polar tube of the germinated spores. Moreover, IFA, enzyme-linked immunosorbent (ELISA) and fluorescence-activated cell sorting (FACS) assays results revealed that NbPTP6 had cell-binding ability. Conclusions:  Based on our results, we have confirmed that NbPTP6 is a novel microsporidian polar tube protein. This protein could adhere with the host cell surface, so we speculated it might play an important role in the process of microsporidian infection. Keywords:  Nosema bombycis, Novel, Polar tube protein, Localization, Cell-binding ability Background Microsporidians are obligate, intracellular, spore-forming parasites and currently considered as a kind of fungi [1–4]. Since the discovery of the first microsporidian Nosema bombycis from silkworms in the 19th century, *Correspondence: [email protected]; [email protected] 1 State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400715, China Full list of author information is available at the end of the article

there are some microsporidians that infect immunocompromised humans such as Encephalitozoon hellem (Eh), E. cuniculi (Ec) and Enterocytozoon bieneusi (Eb) [1, 5]; other microsporidians are insect pathogens such as N. bombycis (Nb), N. ceranae (Nc), and Antonospora locustae (Al) [6–8]. Although microsporidians differ in host range and specificity, they all utilize