title: Molecular characterization of nitrite reductase gene (aniA) and gene product in Neisseria meningitidis isolates: is aniA essential for meningococcal survival?
abstract: The present study evaluates sequence conservation in the gene coding for nitrite reductase (aniA) and AniA expression from a panel of Neisseria meningitidis isolates. Sequence analysis of the coding region in 19 disease-associated and 4 carrier strains notwithstanding a high degree of sequence similarity showed a number of nucleotide changes, some of which possibly resulted in premature translation termination or function loss. In particular, in one disease-associated strain a 9-residues insertion was found to be located close to the type I Cu-site and a catalytic histidine at position 280 was mutated into a leucine. In two strains from carriers, a sequence corresponding to a portion of a transposase gene within the aniA was also found. The AniA protein was always expressed, except for these two carriers strains and for other two strains in which the presence of the premature stop codons was recognized. The biochemical properties of the cloned soluble domain of the enzyme (sAniA) from N. meningitidis reference MC58 strain and from a clinical invasive isolate were studied. In particular, biochemical analysis of sAniA from MC58 demonstrated a clear dependence of its catalytic activity upon acidification, while the clinical isolate-derived sAniA was not functional. Thus, the results obtained suggest that the presence of a conserved and functional aniA gene is not essential for meningococcal survival.
authors.affiliation: Deptartment of Infectious, Parasitic and Immune-mediated diseases, Istituto Superiore di Sanità, Rome, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Stefanelli
authors.forename: Gianni
authors.initials: G
authors.lastname: Colotti
authors.forename: Arianna
authors.initials: A
authors.lastname: Neri
authors.forename: Maria Luisa
authors.initials: ML
authors.lastname: Salucci
authors.forename: Roberto
authors.initials: R
authors.lastname: Miccoli
authors.forename: Luana
authors.initials: L
authors.lastname: Di Leandro
authors.forename: Rodolfo
authors.initials: R
authors.lastname: Ippoliti
mesh_terms: D000328:Adult; D000595:Amino Acid Sequence; D000942:Antigens, Bacterial / Q000235:genetics* / Q000378:metabolism; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D002648:Child; D003001:Cloning, Molecular; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D009345:Neisseria meningitidis / Q000201:enzymology / Q000235:genetics; D009572:Nitrite Reductases / Q000235:genetics* / Q000378:metabolism; D009573:Nitrites / Q000378:metabolism; D016415:Sequence Alignment; D020539:Sequence Analysis, Protein
chemical_list: D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D009573:Nitrites; D009572:Nitrite Reductases