title: Fis overexpression enhances Pseudomonas putida biofilm formation by regulating the ratio of LapA and LapF.
abstract: Bacteria form biofilm as a response to a number of environmental signals that are mediated by global transcription regulators and alarmones. Here we report the involvement of the global transcription regulator Fis in Pseudomonas putida biofilm formation through regulation of lapA and lapF genes. The major component of P. putida biofilm is proteinaceous and two large adhesive proteins, LapA and LapF, are known to play a key role in its formation. We have previously shown that Fis overexpression enhances P. putida biofilm formation. In this study, we used mini-Tn5 transposon mutagenesis to select potential Fis-regulated genes involved in biofilm formation. A total of 90 % of the studied transposon mutants carried insertions in the lap genes. Since our experiments showed that Fis-enhanced biofilm is mostly proteinaceous, the amounts of LapA and LapF from P. putida cells lysates were quantified using SDS-PAGE. Fis overexpression increases the quantity of LapA 1.6 times and decreases the amount of LapF at least 4 times compared to the wild-type cells. The increased LapA expression caused by Fis overexpression was confirmed by FACS analysis measuring the amount of LapA-GFP fusion protein. Our results suggest that the profusion of LapA in the Fis-overexpressed cells causes enhanced biofilm formation in mature stages of P. putida biofilm and LapF has a minor role in P. putida biofilm formation.
authors.affiliation: Institute of Molecular and Cell Biology, University of Tartu, Riia 23, 51010 Tartu, Estonia.
authors.forename: Hanna
authors.initials: H
authors.lastname: Moor
authors.affiliation: Institute of Molecular and Cell Biology, University of Tartu, Riia 23, 51010 Tartu, Estonia.
authors.forename: Annika
authors.initials: A
authors.lastname: Teppo
authors.affiliation: Institute of Molecular and Cell Biology, University of Tartu, Riia 23, 51010 Tartu, Estonia.
authors.forename: Andrio
authors.initials: A
authors.lastname: Lahesaare
authors.affiliation: Institute of Molecular and Cell Biology, University of Tartu, Riia 23, 51010 Tartu, Estonia.
authors.forename: Maia
authors.initials: M
authors.lastname: Kivisaar
authors.affiliation: Institute of Molecular and Cell Biology, University of Tartu, Riia 23, 51010 Tartu, Estonia.
authors.forename: Riho
authors.initials: R
authors.lastname: Teras
mesh_terms: D001426:Bacterial Proteins / Q000096:biosynthesis* / Q000235:genetics; D018441:Biofilms / Q000254:growth & development*; D004251:DNA Transposable Elements; D035021:Factor For Inversion Stimulation Protein / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D055786:Gene Knockout Techniques; D016254:Mutagenesis, Insertional; D016958:Pseudomonas putida / Q000235:genetics / Q000502:physiology*
chemical_list: D001426:Bacterial Proteins; D004251:DNA Transposable Elements; D035021:Factor For Inversion Stimulation Protein