Integrating Vectors for Genetic Studies in the Rare ActinomyceteAmycolatopsis marina

Abstract

Few natural product pathways from rare Actinomycetes have been studied due to the difficulty in applying molecular approaches in these genetically intractable organisms. In this study, we sought to identify integrating vectors, derived using phage int/attP loci, that would efficiently integrate site-specifically in the rare Actinomycete, Amycolatopsis marina DSM45569. Analysis of the genome of A. marina DSM45569 indicated the presence of attB-like sequences for TG1 and R4 integrases. The TG1 and R4 attBs were active in in vitro recombination assays with their cognate purified integrases and attP loci. Integrating vectors containing either the TG1 or R4 int/attP loci yielded exconjugants in conjugation assays from E. coli to A. marina DSM45569. Site-specific recombination of the plasmids into the host TG1 or R4 attB sites was confirmed by sequencing. The presence of homologous TG1 and R4 attB sites in other species of this genus indicates that vectors based on TG1 and R4 integrases could be widely applicable.ImportanceRare Actinomycetes have the same potential of natural product discovery as Streptomyces, but the potential has not been fully explored due to the lack of efficient molecular biology tools. In this study, we identified two serine integrases, TG1 and R4, which could be used in the rare Actinomycetes species, Amycolatopsis marina, as tools for genome integration. The high level of conservation between the attB sites for TG1 and R4 in a number of Amycolatopsis species suggested that plasmids with the integration systems from these phages should be widely useful in this genus.