Non-viability of Haemophilus parasuis fur-defective mutants.
By complementation of an Escherichia coli fur mutant, the Haemophilus parasuis fur gene has been isolated from a genomic library of this organism. The H. parasuis fur gene is the distal one of a three-gene operon. Two genes placed upstream of the H. parasuis fur open-reading frame encode for a hypothetical protein and a flavodoxin, respectively. Attempts performed to isolate an H. parasuis fur-defective mutant either through manganese-resistance selection or exchange markers were unsuccessful. Likewise, anaerobic growth conditions do not enable the attainment of H. parasuis fur-defective mutants either. Nevertheless, H. parasuis clones carrying a knockout mutation in the chromosomal fur gene by insertion of a KmR cassette were obtained when a stable plasmid, containing an additional copy of the transcriptional unit to which the fur gene belongs, was present. Likewise, the presence of a plasmid in which the H. parasuis fur gene is under the control of the Escherichia coli tac promoter allows for the isolation of fur::Km mutants of this organism. Nonetheless, no fur-defective mutants may be isolated from H. parasuis cells harbouring a stable plasmid in which only the single fur gene is contained. These data clearly indicate that H. parasuis cell viability requires the presence of a wild-type fur gene.
Bigas
Anna
A
Department of Genetics and Microbiology, Universitat Autònoma de Barcelona, Bellaterra, 08193 Barcelona, Spain.
Garrido
M A Elena
MA
Badiola
Ignacio
I
Barbé
Jordi
J
Llagostera
Montserrat
M
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D005809:Genes, Regulator; D044137:Haemophilus parasuis / Q000235:genetics* / Q000254:growth & development* / Q000302:isolation & purification / Q000378:metabolism; D007501:Iron / Q000378:metabolism*; D008345:Manganese / Q000494:pharmacology; D016296:Mutagenesis; D016366:Open Reading Frames; D010957:Plasmids; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D014170:Transformation, Genetic; D037521:Virulence Factors
D001426:Bacterial Proteins; D012097:Repressor Proteins; D037521:Virulence Factors; C068477:ferric uptake regulating proteins, bacterial; D008345:Manganese; D007501:Iron