Abstract:
:We have previously shown that in the human pathogen Neisseria meningitidis group B (MenB) more than 200 genes are regulated in response to growth with iron. Among the Fur-dependent, upregulated genes identified by microarray analysis was a putative operon constituted by three genes, annotated as NMB1436, NMB1437 and NMB1438 and encoding proteins with so far unknown function. The operon was remarkably upregulated in the presence of iron and, on the basis of gel retardation analysis, its regulation was Fur dependent. In this study, we have further characterized the role of iron and Fur in the regulation of the NMB1436-38 operon and we have mapped the promoter and the Fur binding site. We also demonstrate by mutant analysis that the NMB1436-38 operon is required for protection of MenB to hydrogen peroxide-mediated killing. By using both microarray analysis and S1 mapping, we demonstrate that the operon is not regulated by oxidative stress signals. We also show that the deletion of the NMB1436-38 operon results in an impaired capacity of MenB to survive in the blood of mice using an adult mouse model of MenB infection. Finally, we show that the NMB1436-38 deletion mutant exhibits increased susceptibility to the killing activity of polymorphonuclears (PMNs), suggesting that the 'attenuated' phenotype is mediated in part by the increased sensitivity to reactive oxygen species-producing cells. This study represents one of the first examples of the use of DNA microarray to assign a biological role to hypothetical genes in bacteria.
journal_name
Mol Microbioljournal_title
Molecular microbiologyauthors
Grifantini R,Frigimelica E,Delany I,Bartolini E,Giovinazzi S,Balloni S,Agarwal S,Galli G,Genco C,Grandi Gdoi
10.1111/j.1365-2958.2004.04315.xsubject
Has Abstractpub_date
2004-11-01 00:00:00pages
962-79issue
4eissn
0950-382Xissn
1365-2958pii
MMI4315journal_volume
54pub_type
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