Mechanism of translation control of the alternative Drosophila melanogaster Voltage Dependent Anion-selective Channel 1 mRNAs

L Leggio,A Messina,A Magrì,M F Tomasello,V Specchia,R Accardi-Gheit,S Reina,F Damiano,M Tommasino,F Guarino

doi:10.1038/s41598-018-23730-7

Abstract

The eukaryotic porin, also called the Voltage Dependent Anion-selective Channel (VDAC), is the main pore-forming protein of the outer mitochondrial membrane. In Drosophila melanogaster, a cluster of genes evolutionarily linked to VDAC is present on chromosome 2L. The main VDAC isoform, called VDAC1 (Porin1), is expressed from the first gene of the cluster. The porin1 gene produces two splice variants, 1A-VDAC and 1B-VDAC, with the same coding sequence but different 5′ untranslated regions (UTRs). Here, we studied the influence of the two 5′ UTRs, 1A-5′ UTR and 1B-5′ UTR, on transcription and translation of VDAC1 mRNAs. In porin-less yeast cells, transformation with a construct carrying 1A-VDAC results in the expression of the corresponding protein and in complementation of a defective cell phenotype, whereas the 1B-VDAC sequence actively represses VDAC expression. Identical results were obtained using constructs containing the two 5′ UTRs upstream of the GFP reporter. A short region of 15 nucleotides in the 1B-5′ UTR should be able to pair with an exposed helix of 18S ribosomal RNA (rRNA), and this interaction could be involved in the translational repression. Our data suggest that contacts between the 5′ UTR and 18S rRNA sequences could modulate the translation of Drosophila 1B-VDAC mRNA. The evolutionary significance of this finding is discussed.

Highlights

The voltage-dependent anion-selective channel (VDAC), known as mitochondrial porin, is the most abundant protein found in the outer mitochondrial membrane of all eukaryotes
No protein band was detected in fractions from cells transformed with 1B-Voltage Dependent Anion-selective Channel (VDAC) (Fig. 2F). These results indicate that 1A-VDAC mRNA is translated, and the protein is correctly targeted to mitochondria (Fig. 2F); this transformed strain complements the phenotype associated with the deletion of the yeast porin gene (Fig. 2A)
We focused on the regulation of expression of VDAC1 in D. melanogaster

Summary

Introduction

The voltage-dependent anion-selective channel (VDAC), known as mitochondrial porin, is the most abundant protein found in the outer mitochondrial membrane of all eukaryotes. Like the mouse and the human, three porin/VDAC proteins are expressed[28,29,30]. In Drosophila melanogaster, the genomic locus 2L 32B 3–4 displays a cluster of four spatially close genes that are evolutionarily linked to VDAC35. Drosophila transposable P elements, when inserted into the porin locus, abolished VDAC expression and were found to produce a lethal phenotype[35]. Imprecise excision of such P elements showed that deletion of exon 1B and of its flanking sequences apparently has no effect on normal fly development or on VDAC protein level, whereas deletion of exon 1A suppresses VDAC protein expression[35]. It was suggested that 1B-VDAC could be an unproductive transcript

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