CAMP protein kinase phosphorylates the Mos1 transposase and regulates its activity: evidences from mass spectrometry and biochemical analyses.

Nicolas Bouchet,Jérôme Jaillet,Martine Cadene,Benjamin Brillet,Guillaume Gabant,Corinne Augé-Gouillou,Luis Briseño-Roa

doi:10.1093/nar/gkt874

Abstract

Genomic plasticity mediated by transposable elements can have a dramatic impact on genome integrity. To minimize its genotoxic effects, it is tightly regulated either by intrinsic mechanisms (linked to the element itself) or by host-mediated mechanisms. Using mass spectrometry, we show here for the first time that MOS1, the transposase driving the mobility of the mariner Mos1 element, is phosphorylated. We also show that the transposition activity of MOS1 is downregulated by protein kinase AMP cyclic-dependent phosphorylation at S170, which renders the transposase unable to promote Mos1 transposition. One step in the transposition cycle, the assembly of the paired-end complex, is specifically inhibited. At the cellular level, we provide evidence that phosphorylation at S170 prevents the active transport of the transposase into the nucleus. Our data suggest that protein kinase AMP cyclic-dependent phosphorylation may play a double role in the early stages of genome invasion by mariner elements.

Highlights

The transposition of genetic elements is potentially genotoxic for the host cell despite being an essential tool for perpetuating genome plasticity, and for its evolutionary potential
We identified the mechanism by which phosphorylation at residue S170 (pS170) prevents transposition, and showed that it impairs the assembly of the paired-end complex (PEC), probably by steric hindrance and/or charge repulsion
We expressed Mos1 transposase (MOS1) using a baculovirus/insect cell system, as this involves the expression of MOS1 in a cellular context similar to that of the native host (Drosophila species)

Summary

Introduction

The transposition of genetic elements is potentially genotoxic for the host cell despite being an essential tool for perpetuating genome plasticity, and for its evolutionary potential. This means that tight regulation of transposition is essential to maintain the balance between maintaining active transposons in host genomes and preventing the damage they could cause by potentially lethal DNA rearrangements. Little is known about host-mediated regulatory mechanisms, which are triggered when a transposon invades a naive genome that may be nonspecialized mechanisms widely used by eukaryotic cells. They could consist of posttranslational modifications (PTMs), which are often found to drive the regulation of protein activity. PTM could directly alter protein activity, making it unable to promote any biochemical process

Methods

Results

Conclusion