Conditional gene silencing in the Antarctic bacterium Pseudoalteromonas haloplanktis TAC125.

Since the release in 2005 of the genome sequence and annotation of the first Antarctic marine bacterium, the number of genomes of psychrophilic microorganisms in public databases has steadily increased. Unfortunately, the lack of effective molecular tools for the manipulation of these environmental strains still hampers our understanding of their peculiar strategies to thrive in freezing conditions, limiting the functional genomics approaches to differential analyses only. Over the past two decades, our research group established the first effective gene cloning/expression technology in the Antarctic Gram-negative marine bacterium Pseudoalteromonas haloplanktis TAC125. The setup of a genome mutagenesis technique (based on homologous recombination and counterselection events) further supported the use of this strain, which became an attractive model for studying microbial adaptations to freezing lifestyle. Moreover, to further extend the functional analyses to its essential genes, the set-up of a conditional gene silencing approach is desirable. In this paper, we report the development of an asRNA regulatory system in the Antarctic bacterium, testing the feasibility of Hfq-dependent and PTasRNA strategies previously developed in Escherichia coli. Stable and efficient silencing of two chromosomal genes was obtained by using PTasRNAs, reaching very high levels of downregulation.