Ribosomal protein relocation through recombineering: assessing evolutionary meaning of a precise genomic position.

SOLER BISTUE A; MONDOTTE JA; VAL ME; BLAND MJ

Leipzig

Congreso; IV Congress of Eurpean Microbiologists; 2013

Federation of European Microbiological Societies

Background and aims:Comparative genomics revealed a conservedtrend in genome organization of fast-growing bacteria: position of ribosomalprotein genes is biased towards origin of replication (oriC). This location would allow increased gene dosage during earlyexponential phase. However experimental evidence for this hypothesis islacking. Vibrio cholerae, a bichromosomalfast-growing pathogen is an experimental model genetically well characterizedand easy to handle. As S10-spc-α(S10) encodes half of the ribosomal protein genes we tested relocation effectsof this is a highly conserved locus.Methods:Transpositions were achieved by transientexpression of lamboid phage recombinases after insertion of phage attL and attRsites flanking S10.Results:Recombinogenic tools allowed the precise S10movement along the genome to analyze re-positioning effects. Movement from itsoriginal location is well tolerated. Relocation within chromosome 1 delaysgeneration time (GT) in fast growing conditions. Variation on GT correlateswith distance from its original position. Transposition to chromosome 2displayed similar effects but, interestingly, orientation also plays a role.Infection tests on the model organism Drosophilamelanogaster showed that mutants are highly delayed in host invasion.Conclusions:S10 can be moved along Vibrio cholerae?s genome. Downstream relocation of S10-spec-α showed longer GT.Re-positioning effects on chromosome 2 might go beyond oriC-linked gene dosage. S10 movement strongly impaired infection.Our observations show how strong selective pressure drove this locus near oriC. Understanding how genome structureinfluences bacterial physiology will contribute to the field of syntheticbiology and might allow rational GT reprogramming in bacteria.