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Molecular architecture of the Mos1 paired-end complex: the structural basis of DNA transposition in a eukaryote.

ABSTRACT: A key step in cut-and-paste DNA transposition is the pairing of transposon ends before the element is excised and inserted at a new site in its host genome. Crystallographic analyses of the paired-end complex (PEC) formed from precleaved transposon ends and the transposase of the eukaryotic element Mos1 reveals two parallel ends bound to a dimeric enzyme. The complex has a trans arrangement, with each transposon end recognized by the DNA binding region of one transposase monomer and by the active site of the other monomer. Two additional DNA duplexes in the crystal indicate likely binding sites for flanking DNA. Biochemical data provide support for a model of the target capture complex and identify Arg186 to be critical for target binding. Mixing experiments indicate that a transposase dimer initiates first-strand cleavage and suggest a pathway for PEC formation.

SUBMITTER: Richardson JM

PROVIDER: S-EPMC3977044 | biostudies-literature | 2009 Sep

REPOSITORIES: biostudies-literature

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Molecular architecture of the Mos1 paired-end complex: the structural basis of DNA transposition in a eukaryote.

Richardson Julia M JM Colloms Sean D SD Finnegan David J DJ Walkinshaw Malcolm D MD

Cell 20090901 6

A key step in cut-and-paste DNA transposition is the pairing of transposon ends before the element is excised and inserted at a new site in its host genome. Crystallographic analyses of the paired-end complex (PEC) formed from precleaved transposon ends and the transposase of the eukaryotic element Mos1 reveals two parallel ends bound to a dimeric enzyme. The complex has a trans arrangement, with each transposon end recognized by the DNA binding region of one transposase monomer and by the activ ...[more]

PMID: 19766564

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Project description:BackgroundMariner elements represent the most successful family of autonomous DNA transposons, being present in various plant and animal genomes, including humans. The introduction and co-evolution of mariners within host genomes imply a strict regulation of the transposon activity. Biochemical data accumulated during the past decade have led to a convergent picture of the transposition cycle of mariner elements, suggesting that mariner transposition does not rely on host-specific factors. This model does not account for differences of transposition efficiency in human cells between mariners. We thus wondered whether apparent similarities in transposition cycle could hide differences in the intrinsic parameters that control mariner transposition.Principal findingsWe find that Mos1 transposase concentrations in excess to the Mos1 ends prevent the paired-end complex assembly. However, we observe that Mos1 transposition is not impaired by transposase high concentration, dismissing the idea that transposase over production plays an obligatory role in the down-regulation of mariner transposition. Our main finding is that the paired-end complex is formed in a cooperative way, regardless of the transposase concentration. We also show that an element framed by two identical ITRs (Inverted Terminal Repeats) is more efficient in driving transposition than an element framed by two different ITRs (i.e. the natural Mos1 copy), the latter being more sensitive to transposase concentration variations. Finally, we show that the current Mos1 ITRs correspond to the ancestral ones.ConclusionsWe provide new insights on intrinsic properties supporting the self-regulation of the Mos1 element. These properties (transposase specific activity, aggregation, ITR sequences, transposase concentration/transposon copy number ratio...) could have played a role in the dynamics of host-genomes invasion by Mos1, accounting (at least in part) for the current low copy number of Mos1 within host genomes.

Dataset Information

Molecular architecture of the Mos1 paired-end complex: the structural basis of DNA transposition in a eukaryote.

Publications

Molecular architecture of the Mos1 paired-end complex: the structural basis of DNA transposition in a eukaryote.

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