In vitro Tn7 mutagenesis of Haemophilus influenzae Rd and characterization of the role of atpA in transformation.
Haemophilus influenzae Rd is a gram-negative bacterium capable of natural DNA transformation. The competent state occurs naturally in late exponential growth or can be induced by a nutritional downshift or by transient anaerobiosis. The genes cya, crp, topA, and sxy (tfoX) are known to function in the regulation of competence development. The phosphoenolpyruvate:carbohydrate phosphotransferase system functions to maintain levels of cyclic AMP necessary for competence development but is not directly involved in regulation. The exact signal(s) for competence and the genes that mediate the signal(s) are still unknown. In an effort to find additional regulatory genes, H. influenzae Rd was mutated by using an in vitro Tn7 system and screened for mutants with a reduced ability to induce the competence-regulatory gene, comA. Insertions in atpA, a gene coding for the alpha subunit of the F1 cytoplasmic domain of the ATP synthase, reduce transformation frequencies about 20-fold and cause a significant reduction in expression of competence-regulatory genes, while the expression of constitutive competence genes is only minimally affected. In addition, we found that an insertion in atpB, which encodes the a subunit of the F0 membrane-spanning domain, has a similar effect on transformation frequencies.
Gwinn
M L
ML
Department of Molecular Biology and Genetics, Johns Hopkins University, School of Medicine, Baltimore, Maryland 21205, USA. mlgwinn@tigr.org
Stellwagen
A E
AE
Craig
N L
NL
Tomb
J F
JF
Smith
H O
HO
D001426:Bacterial Proteins / Q000235:genetics; D004251:DNA Transposable Elements; D004268:DNA-Binding Proteins / Q000235:genetics; D005798:Genes, Bacterial; D006193:Haemophilus influenzae / Q000201:enzymology / Q000235:genetics*; D007658:Ketone Oxidoreductases / Q000235:genetics; D016254:Mutagenesis, Insertional; D010641:Phenotype; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000235:genetics; D017852:Phosphotransferases (Nitrogenous Group Acceptor) / Q000235:genetics; D006180:Proton-Translocating ATPases / Q000235:genetics*; D050743:Pyruvate Synthase; D012641:Selection, Genetic; D014170:Transformation, Genetic
D001426:Bacterial Proteins; C061262:ComA protein, Bacteria; D004251:DNA Transposable Elements; D004268:DNA-Binding Proteins; D007658:Ketone Oxidoreductases; D050743:Pyruvate Synthase; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; D017852:Phosphotransferases (Nitrogenous Group Acceptor); C022360:phosphoenolpyruvate-protein phosphotransferase; D006180:Proton-Translocating ATPases