Type 3 Fimbriae Encoded on Plasmids Are Expressed from a Unique Promoter without Affecting Host Motility, Facilitating an Exceptional Phenotype That Enhances Conjugal Plasmid Transfer.
Horizontal gene transfer (HGT), the transmission of genetic material to a recipient that is not the progeny of the donor, is fundamental in bacterial evolution. HGT is often mediated by mobile genetic elements such as conjugative plasmids, which may be in conflict with the chromosomal elements of the genome because they are independent replicons that may petition their own evolutionary strategy. Here we study differences between type 3 fimbriae encoded on wild type plasmids and in chromosomes. Using known and newly characterized plasmids we show that the expression of type 3 fimbriae encoded on plasmids is systematically different, as MrkH, a c-di-GMP dependent transcriptional activator is not needed for strong expression of the fimbriae. MrkH is required for expression of type 3 fimbriae of the Klebsiella pneumoniae chromosome, wherefrom the fimbriae operon (mrkABCDF) of plasmids is believed to have originated. We find that mrkABCDFs of plasmids are highly expressed via a unique promoter that differs from the original Klebsiella promoter resulting in fundamental behavioral consequences. Plasmid associated mrkABCDFs did not influence the swimming behavior of the host, that hereby acquired an exceptional phenotype being able to both actively swim (planktonic behavior) and express biofilm associated fimbriae (sessile behavior). We show that this exceptional phenotype enhances the conjugal transfer of the plasmid.
Department of Biology, University of Copenhagen, Copenhagen, Denmark.
Jonas Stenløkke
JS
Madsen
Department of Biology, University of Copenhagen, Copenhagen, Denmark.
Leise
L
Riber
Department of Environmental Sciences, Aarhus University, Aarhus, Denmark.|Department of Biology, University of Copenhagen, Copenhagen, Denmark.
Witold
W
Kot
Max Planck Research Group Chromosome Organization and Dynamics, Max Planck Institute of Biochemistry, Martinsried, Germany.|Department of Biology, University of Copenhagen, Copenhagen, Denmark.
Alrun
A
Basfeld
Department of Biology, University of Copenhagen, Copenhagen, Denmark.
Mette
M
Burmølle
Department of Environmental Sciences, Aarhus University, Aarhus, Denmark.|Department of Biology, University of Copenhagen, Copenhagen, Denmark.
Lars Hestbjerg
LH
Hansen
Department of Biology, University of Copenhagen, Copenhagen, Denmark.
Søren Johannes
SJ
Sørensen
D018441:Biofilms; D010861:Fimbriae, Bacterial / Q000378:metabolism*; D022761:Gene Transfer, Horizontal; D010641:Phenotype; D010957:Plasmids; D011401:Promoter Regions, Genetic