Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0348321 (Haemophilus)
 15,372 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Previously, we characterized a pathway necessary for the processing of NAD+ and for uptake of nicotinamide riboside (NR) in Haemophilus influenzae. Here we report on the role of NadR, which is essential for NAD+ utilization in this organism. Different NadR variants with a deleted ribonucleotide kinase domain or with a single amino acid change were characterized in vitro and in vivo with respect to cell viability, ribonucleotide kinase activity, and NR transport. The ribonucleotide kinase mutants were viable only in a nadV+ (nicotinamide phosphoribosyltransferase) background, indicating that the ribonucleotide kinase domain is essential for cell viability in H. influenzae. Mutations located in the Walker A and B motifs and the LID region resulted in deficiencies in both NR phosphorylation and NR uptake. The ribonucleotide kinase function of NadR was found to be feedback controlled by NAD+ under in vitro conditions and by NAD+ utilization in vivo. Taken together, our data demonstrate that the NR phosphorylation step is essential for both NR uptake across the inner membrane and NAD+ synthesis and is also involved in controlling the NAD+ biosynthesis rate.
 ...
PMID:Coupling of NAD+ biosynthesis and nicotinamide ribosyl transport: characterization of NadR ribonucleotide kinase mutants of Haemophilus influenzae. 1596 50

The aim of this study was to reinvestigate the relationships and the generic affiliations of the species Actinobacillus actinomycetemcomitans, Haemophilus aphrophilus, Haemophilus paraphrophilus and Haemophilus segnis. The nicotinamide phosphoribosyltransferase gene (nadV) conferring V factor-independent growth was identified in Haemophilus aphrophilus. The gene encodes a polypeptide of 462 amino acids that shows 74.5 % amino acid sequence identity to the corresponding enzyme from Actinobacillus actinomycetemcomitans. Ten isolates of Haemophilus paraphrophilus all carried a nadV pseudogene. DNA from Haemophilus aphrophilus was able to transform Haemophilus paraphrophilus into the NAD-independent phenotype. The transformants carried a full-length nadV inserted in the former locus of the pseudogene. The DNA-DNA relatedness between the type strains of Haemophilus aphrophilus and Haemophilus paraphrophilus was 77 %. We conclude that the division into two species Haemophilus aphrophilus and Haemophilus paraphrophilus is not justified and that Haemophilus paraphrophilus should be considered a later heterotypic synonym of Haemophilus aphrophilus. Forty strains of Actinobacillus actinomycetemcomitans, Haemophilus aphrophilus and Haemophilus segnis were investigated by multilocus sequence analysis. The 40 strains form a monophyletic group clearly separate from other evolutionary lineages of the family Pasteurellaceae. We propose the transfer of Actinobacillus actinomycetemcomitans, Haemophilus aphrophilus and Haemophilus segnis to a new genus Aggregatibacter gen. nov. as Aggregatibacter actinomycetemcomitans comb. nov. (the type species; type strain ATCC 33384(T)=CCUG 13227(T)=CIP 52.106(T)=DSM 8324(T)=NCTC 9710(T)), Aggregatibacter aphrophilus comb. nov. (type strain ATCC 33389(T)=CCUG 3715(T)=CIP 70.73(T)=NCTC 5906(T)) and Aggregatibacter segnis comb. nov. (type strain HK316(T)=ATCC 33393(T)=CCUG 10787(T)=CCUG 12838(T)=CIP 103292(T)=NCTC 10977(T)). The species of the genus Aggregatibacter are independent of X factor and variably dependent on V factor for growth in vitro.
 ...
PMID:Reclassification of Actinobacillus actinomycetemcomitans, Haemophilus aphrophilus, Haemophilus paraphrophilus and Haemophilus segnis as Aggregatibacter actinomycetemcomitans gen. nov., comb. nov., Aggregatibacter aphrophilus comb. nov. and Aggregatibacter segnis comb. nov., and emended description of Aggregatibacter aphrophilus to include V factor-dependent and V factor-independent isolates. 1695 11