Abstract
Rieske iron-sulfur protein (RISP) is a key protein subunit of mitochondrial complex III which plays an important role in the respiratory electron transport chain. The complete cDNA of RISP was cloned from Spodoptera exigua by real time quantitative PCR and rapid-amplification of cDNA ends (RACE) technology and named as SeRISP (GenBank Accession Number: JN992290). Multiple alignments and the creation of a phylogenetic tree revealed that RISPs are highly conserved among different insects, and the highly conserved region of RISPs is mainly located at the C-terminal which serves as the functional domain. Expression pattern analysis demonstrated that SeRISP is expressed in all developmental stages of S. exigua; the expression levels increased during larval growth, remained stable during development from fourth instar to pupa and reached a peak in the adult. In addition, SeRISP was significantly suppressed at both the mRNA and protein levels by feeding the instar stage with dsRNA; levels of suppression increased with increasing dsRNA concentration and continuous treatment time. The silencing of SeRISP in larvae led to the significant inhibition of ATP synthesis and larval growth, which could result in energy reserve deficiency in pupae and the suppression of fecundity and hatchability in adults. Our findings confirmed that it is possible to silence target genes in S. exigua by simple dsRNA feeding, and provided evidence of the essential role of RISP in the process of ATP synthesis, growth and reproduction.
Highlights
Mitochondria are vital for an extensive number of cellular processes, yet hundreds of proteins involved in this process lack precise identification and robust functional annotation (Floyd Brendan et al, 2016; Li et al, 2017)
A 702 bp fragment was amplified from the cDNA of S. exigua using the degenerate primers SeRISPDF and SeRISPDR
Our results demonstrated that the full sequence of SeRISP shared 96.0% identity with the Rieske iron-sulfur protein (RISP) gene from S. litura at the amino acid level (GenBank Accession Number: HQ599193.1).We called this sequence SeRISP and submitted to GenBank (Accession Number: JN992290)
Summary
Mitochondria are vital for an extensive number of cellular processes, yet hundreds of proteins involved in this process lack precise identification and robust functional annotation (Floyd Brendan et al, 2016; Li et al, 2017). Protein complex III, consisting of cytochrome c1, two forms of cytochrome b (b562 and b566) and a rieske iron-sulfur protein (RISP) containing a high potential rieske [2Fe-2S] cluster, is known to play an important role in the function of ATP synthase (Moghaddam et al, 2017). It does this, by Functional Analysis of Rieske Iron-Sulfur Protein generating an electrochemical potential on both sides of the mitochondrial inner membrane for ATP synthesis (Heinrich et al, 2017). The α-subunit of ATP synthase could be considered as a potential target for insect pest control (Hu and Xia, 2016)
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