Identification and subcellular colocalization of protein transport protein Sec61α and Sec61γ in Nosema bombycis

The main function of Sec61 complex is participating in the transport of polypeptide chains across the endo-plasmic reticulum. The Sec61 alpha subunit is the largest subunit of the Sec61 complex and shows high degree of conservation. In this study, we identified the NbSec61 alpha and NbSec61 gamma genes in the microsporidian Nosema bombycis for the first time. Multiple sequence alignment showed that the sequence similarity between NbSec61 alpha and homologous proteins of other microsporidia was greater than 48 %. NbSec61 alpha contains a plug domain (amino acids 40-74) unique to the Sec61/SecY complex. Phylogenetic analysis based on NbSec61 alpha and NbSec61 gamma indicated that the N. bombycis was closely related to Nosema granulosis, Nosema ceranae and Nosema apis. Indirect immunfluorescence assay showed that NbSec61 alpha and NbSec61 gamma were mainly distributed in the perinuclear re-gion of N. bombycis in different developmental phases. qRT-PCR results revealed that the expression level of NbSec61 alpha gene increased in the early stage and reached the highest at 48 h, then decreased in the late stages. After knockdown of NbSec61 alpha, the expression of NbSec61 alpha, NbSec61 gamma and NbssrRNA genes were all significantly down-regulated. These results suggest that the NbSec61 alpha and NbSec61 gamma may play an important role in the intracellular development of N. bombycis.

Automated summary

In this study, the NbSec61 alpha and NbSec61 gamma genes were identified in the microsporidian Nosema bombycis for the first time. These genes were found to play important roles in the transport across the endoplasmic reticulum and intracellular development of N. bombycis.