Unmasking the ancestral activity of integron integrases reveals a smooth evolutionary transition during functional innovation.

Unmasking the ancestral activity of integron integrases reveals a smooth evolutionary transition during functional innovation.

Escudero JA, Loot C, Parissi V, Nivina A, Bouchier C, Mazel D.
Nat Commun. 2016 Mar 10;7:10937. doi: 10.1038/ncomms10937.

Un cas d’innovation évolutive fonctionnelle sans à-coups : les intégrases d’intégrons

Nos travaux menés en collaboration avec l’équipe de Didier Mazel à l’Institut Pasteur, décrivent comment les intégrases des intégrons bactériens ont acquis, au cours de l’évolution, l’aptitude à reconnaître et recombiner des ADN simple brin tout en conservant leur capacité ancestrale canonique de recombiner des ADN double brin. Ceci prouve que les deux fonctions peuvent coexister, et fournit une illustration rarement observée dans les processus d’innovation évolutive, d’une étape intermédiaire bi-fonctionnelle.

Abstract:

Tyrosine (Y)-recombinases have evolved to deliver mechanistically different reactions on a variety of substrates, but these evolutionary transitions are poorly understood. Among them, integron integrases are hybrid systems recombining single- and double-stranded DNA partners. These reactions are asymmetric and need a replicative resolution pathway, an exception to the canonical second strand exchange model of Y-recombinases. Integron integrases possess a specific domain for this specialized pathway. Here we show that despite this, integrases are still capable of efficiently operating the ancestral second strand exchange in symmetrical reactions between double-stranded substrates. During these reactions, both strands are reactive and Holliday junction resolution can follow either pathway. A novel deep-sequencing approach allows mapping of the crossover point for the second strand exchange. The persistence of the ancestral activity in integrases illustrates their robustness and shows that innovation towards new recombination substrates and resolution pathways was a smooth evolutionary process.

Contact :

Vincent Parissi – UMR CNRS 3254 / vincent.parissi@u-bordeaux.fr

LOGO-UNIVERSITE-BORDEAUX inserm57x16mmHD logo cnrs chu bergoni
Mentions Légales