title: The Hfq-dependent small noncoding RNA NrrF directly mediates Fur-dependent positive regulation of succinate dehydrogenase in Neisseria meningitidis.
abstract: Previous microarray studies have suggested that an indirect mechanism of Fur regulation may be present in meningococcus at the posttranscriptional level through a small regulatory RNA (sRNA) system analogous to that of Escherichia coli and Pseudomonas aeruginosa. Recently, a Fur-regulated sRNA, NrrF, was identified that is involved in the iron regulation of the sdhA and sdhC succinate dehydrogenase genes. Here we report a detailed transcriptional analysis of the nrrF gene and show that NrrF is a Hfq-dependent sRNA. The Hfq protein mediates nrrF downregulation and Fur-dependent upregulation of the sdhCDAB operon, the major in vivo NrrF-regulated operon. NrrF forms a duplex in vitro with a region of complementarity overlapping the sdhDA mRNA junction. Furthermore, Hfq binds to NrrF in vitro and considerably enhances the efficiency of the interaction of the sRNA with the identified target. Our data suggest that Hfq-meditated binding of NrrF to the in vivo target in the sdhCDAB mRNA may cause the rapid degradation of the transcript, resulting in Fur-dependent positive regulation of succinate dehydrogenase. In addition, while the upregulation of sodB and fumB by Fur is dependent on the Hfq protein, it is unaffected in the nrrF knockout, which suggests that there is more than one sRNA regulator involved in iron homeostasis in meningococcus.
authors.affiliation: Novartis Vaccines, Via Fiorentina 1, 53100 Siena, Italy.
authors.forename: Matteo M E
authors.initials: MM
authors.lastname: Metruccio
authors.forename: Laura
authors.initials: L
authors.lastname: Fantappiè
authors.forename: Davide
authors.initials: D
authors.lastname: Serruto
authors.forename: Alessandro
authors.initials: A
authors.lastname: Muzzi
authors.forename: Davide
authors.initials: D
authors.lastname: Roncarati
authors.forename: Claudio
authors.initials: C
authors.lastname: Donati
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Scarlato
authors.forename: Isabel
authors.initials: I
authors.lastname: Delany
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology*; D009345:Neisseria meningitidis / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D022661:RNA, Untranslated / Q000235:genetics / Q000378:metabolism*; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D013385:Succinate Dehydrogenase / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D022661:RNA, Untranslated; D012097:Repressor Proteins; C068477:ferric uptake regulating proteins, bacterial; D013385:Succinate Dehydrogenase