title: The kfrA gene is the first in a tricistronic operon required for survival of IncP-1 plasmid R751.
abstract: The kfrA gene of the IncP-1 broad-host-range plasmids is the best-studied member of a growing gene family that shows strong linkage to the minimal replicon of many low-copy-number plasmids. KfrA is a DNA binding protein with a long, alpha-helical, coiled-coil tail. Studying IncP-1beta plasmid R751, evidence is presented that kfrA and its downstream genes upf54.8 and upf54.4 were organized in a tricistronic operon (renamed here kfrA kfrB kfrC), expressed from autoregulated kfrAp, that was also repressed by KorA and KorB. KfrA, KfrB and KfrC interacted and may have formed a multi-protein complex. Inactivation of either kfrA or kfrB in R751 resulted in long-term accumulation of plasmid-negative bacteria, whereas wild-type R751 itself persisted without selection. Immunofluorescence studies showed that KfrA(R751) formed plasmid-associated foci, and deletion of the C terminus of KfrA caused plasmid R751DeltaC2kfrA foci to disperse and mislocalize. Thus, the KfrABC complex may be an important component in the organization and control of the plasmid clusters that seem to form the segregating unit in bacterial cells. The studied operon is therefore part of the set of functions needed for R751 to function as an efficient vehicle for maintenance and spread of genes in Gram-negative bacteria.
authors.affiliation: Central Institute of Labour Protection, National Research Institute, 00-701 Warsaw, Czerniakowska 16, Poland.|The Institute of Biochemistry and Biophysics, Polish Academy of Sciences (PAS), 02-106 Warsaw, Pawinskiego 5A, Poland.
authors.forename: Malgorzata
authors.initials: M
authors.lastname: Adamczyk
authors.affiliation: The Institute of Biochemistry and Biophysics, Polish Academy of Sciences (PAS), 02-106 Warsaw, Pawinskiego 5A, Poland.
authors.forename: Patrycja
authors.initials: P
authors.lastname: Dolowy
authors.affiliation: The Institute of Biochemistry and Biophysics, Polish Academy of Sciences (PAS), 02-106 Warsaw, Pawinskiego 5A, Poland.
authors.forename: Michal
authors.initials: M
authors.lastname: Jonczyk
authors.affiliation: School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Thomas
authors.affiliation: The Institute of Biochemistry and Biophysics, Polish Academy of Sciences (PAS), 02-106 Warsaw, Pawinskiego 5A, Poland.
authors.forename: Grazyna
authors.initials: G
authors.lastname: Jagura-Burdzy
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D003227:Conjugation, Genetic; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D048168:Escherichia coli K12 / Q000235:genetics* / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D009876:Operon; D010957:Plasmids / Q000235:genetics / Q000502:physiology*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D014170:Transformation, Genetic
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins