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Query: UMLS:C0348321 (Haemophilus)
 15,372 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A variety of biologically important pyridine nucleotides and precursors were examined for their capacities to serve as substrates for the synthesis of NAD by cell fractions derived from Haemophilus parasuis and H. pleuropneumoniae. Of the compounds tested, only NMN and nicotinamide riboside were converted to NAD. These reactions required ATP as co-substrate, and fractions from both organisms could also catalyze the ATP-dependent synthesis of NADP from NAD. In the absence of ATP, and depending on the pyridine compound under study, NAD, NMN, nicotinamide riboside, and also nicotinamide, were detected as products of catabolism. It is concluded that these haemophili possess either three-membered pyridine nucleotide cycles or two-membered cycles with synthetic branches originating with nicotinamide riboside. It is also possible that the pyridine nucleotide cycles of both organisms have nonrecycling branches resulting in the "waste" of usable pyridine compound in the form of nicotinamide.
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PMID:Pyridine nucleotide metabolism by extracts derived from Haemophilus parasuis and H. pleuropneumoniae. 294 87

The utilization of exogenous nicotinamide adenine dinucleotide (NAD) by Haemophilus parainfluenzae was studied in suspensions of whole cells using radiolabelled NAD, nicotinamide mononucleotide (NMN), and nicotinamide ribonucleoside (NR). The utilization of these compounds by H. parainfluenzae has the following characteristics. (1) NAD is not taken up intact, but rather is degraded to NMN or NR prior to internalization. (2) Uptake is carrier-mediated and energy-dependent with saturation kinetics. (3) There is specificity for the beta-configuration of the glycopyridine linkage. (4) An intact carboxamide groups is required on the pyridine ring. The intracellular metabolism of NAD was studied in crude cell extracts and in whole cells using carbonyl-14C-labelled NR, NMN, NAD, nicotinamide, and nicotinic acid as substrates in separate experiments. A synthetic pathway from NR through NMN to NAD that requires Mg2+ and ATP was demonstrated. Nicotinamide was found as an end-product of NAD degradation. Nicotinic acid mononucleotide and nicotinic acid adenine dinucleotide were not found as intermediates. The NAD synthetic pathway in H. parainfluenzae differs from the Preiss-Handler pathway and the pyridine nucleotide cycles described in other bacteria.
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PMID:Utilization and metabolism of NAD by Haemophilus parainfluenzae. 325 36

The genomic organization of the chromosomal cps region that is responsible for capsular polysaccharide synthesis in Klebsiella pneumoniae Chedid (O1:K2) was investigated. Deletion analyses and Southern hybridization studies suggested that the central region of the cloned 29-kb BamHI fragment is indispensable for K2 capsular polysaccharide synthesis. The 24,329-bp nucleotide sequence of the Klebsiella cps region was determined and deposited in the EMBL and GenBank databases through DDBJ and assigned accession number D21242. Nineteen possible open reading frames (ORFs) were identified in the sequenced area. Among them, 13 ORFs are very close to each other. Six of the 19 ORFs show considerable nucleotide sequence similarities to Salmonella typhimurium cpsG, cpsB, rfbP, and orf2.8, Escherichia coli gnd, and Haemophilus influenzae bexD, respectively. Moreover, the deduced amino acid sequence of the ORF10 product demonstrated a highly hydrophobic profile and showed putative membrane topology similarity to Rickettsia prowazekii ATP/ADP translocase. Nucleotide sequence similar to the sigma 54-dependent promoter, as well as the usual -35 and -10 sequences, were identified just upstream of ORF3, which is the first ORF in the polycistronic structure. Furthermore, a sequence (GGGCGGTAGCGT) found just downstream of the sigma 54-dependent promoter-like sequence was generally conserved among gene clusters implicated in cell surface polysaccharide synthesis, such as Salmonella rfb and viaB and E. coli kpsMT and rfaQPG. A possible transcriptional terminator with a hairpin loop structure found just downstream of ORF15 that is a homolog of E. coli gnd. K2 capsular polsaccharide biosynthesis in E. coli K-12 depends on cpsB (mannose-1-phosphate guanyltransferase gene), and Klebsiella cpsB, found in the downstream region of the polycistronic structure, was able to complement cpsB of E. coli. Results of transposon insertion and promoter-cloning analyses were consistent with the results of nucleotide sequence analysis.
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PMID:Genomic organization of the Klebsiella pneumoniae cps region responsible for serotype K2 capsular polysaccharide synthesis in the virulent strain Chedid. 789 2

The nucleotide sequence of a 4243-bp PstI fragment containing the rec-2 gene of Haemophilus influenzae was determined. The amino acid (aa) sequences of four putative proteins were deduced from the corresponding open reading frames (ORFs). The 2400-bp ORF2 accounted for rec-2, based on the sequences of DNA fragments that contained rec-2::mini-Tn10 mutations. The rec-2 gene encoded a putative 800-aa protein with a M(r) of 90,561. Sequence analysis suggested that the rec-2 product contained nine highly probable integral membrane-spanning segments. Database searches showed that rec-2 was homologous to the comE-ORF3 gene of Bacillus subtilis. This hypothesis is consistent with the known involvement of both of these genes in the passage of transforming DNA through the competent-cell envelope. Although the sequences of the other three ORFs were incomplete, sufficient data were available to allow inferences about their homologies to other genes. ORF4, which overlapped ORF1, was homologous to the Escherichia coli dnaK suppressor gene, dksA, and therefore was named dsh-1 (dnaK suppressor homolog). Mutations in dsh-1 and its putative promoter region caused a mild sensitivity to UV light, but did not affect DNA recombination. ORF3, located downstream from rec-2, was homologous to msbA, an essential gene of E. coli with extensive similarity to the ATP-dependent translocators. ORF3 was named msh-1 (msbA homolog). Mutations in msh-1 had no effects on genetic transformation. The close juxtaposition of rec-2 and msh-1 implied that the expression of msh-1 could be linked to the translation of the rec-2 ORF.
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PMID:Sequence of the rec-2 locus of Haemophilus influenzae: homologies to comE-ORF3 of Bacillus subtilis and msbA of Escherichia coli. 806 12

The kps locus for polysialic acid capsule expression in Escherichia coli K1 is composed of a central group of biosynthetic neu genes, designated region 2, flanked on either side by region 1 or region 3 kps genes with poorly defined functions. Chromosomal mutagenesis with MudJ and subsequent complementation analysis, maxicell and in vitro protein expression studies, and nucleotide sequencing identified the region 1 gene, kpsE, which encodes a 39-kDa polypeptide. Polarity of the kpsE::lacZ mutation suggests an operonic structure for region 1. KpsE is homologous to putative polysaccharide-translocation components previously identified in Haemophilus influenzae type b and Neisseria meningitidis group B. An open reading frame upstream of kpsE encodes a 35-kDa polypeptide with homology to GutQ, a putative ATP-binding protein of unknown function encoded by gutQ of the glucitol utilization operon. Whether expression of the gutQ homolog as the potential first gene of region 1 is required for polysialic acid synthesis or localization is presently unknown.
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PMID:Cloning, sequencing, expression, and complementation analysis of the Escherichia coli K1 kps region 1 gene, kpsE, and identification of an upstream open reading frame encoding a protein with homology to GutQ. 825 90

A 6.2-kb Haemophilus influenzae genomic DNA fragment which partially complemented both the mutator and ultraviolet light sensitive (UVs) phenotypes of the H. influenzae mutB1 mutant was isolated. This fragment was also able to complement the UVs phenotype of Escherichia coli uvrD mutant hosts. The uvrD+ gene complemented the mutator phenotype of mutB1 hosts. The nucleotide (nt) sequence of the 6.2-kb fragment revealed an open reading frame (ORF) of 2184 bp. This ORF shows similarity at both the nt and amino acid (aa) levels with the uvrD gene of E. coli. Comparison of the sequences revealed eight regions of aa conservation in addition to seven previously identified helicase superfamily domains. The nt sequence 5' to the mutB ORF contains several potential regulatory motifs, including a LexA-binding site. Based upon these observations, we are confident that the mutB gene of H. influenzae encodes an ATP-dependent DNA helicase-like activity.
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PMID:The sequence of the Haemophilus influenzae mutB gene indicates it encodes a DNA helicase II-like protein. 829 31

We have sequenced and genetically characterized comF, a Bacillus subtilis competence locus, previously identified by Tn917 transposon insertion mutagenesis. Expression of the locus, in which three open reading frames (ORFs) were found, is driven by a single sigma A-like promoter in front of comFORF1 and is dependent on early regulatory competence genes and only expressed in competence medium. The predicted amino acid sequences of two of the ORFs showed similarities to known proteins in the GenBank and SwissProt databases: ComFORF1 is similar to an extensive family of ATP-dependent RNA/DNA helicases with closer similarity to the DEAD protein subfamily and to the PriA protein in Escherichia coli. The latter is a DNA translocase/helicase required for primosome assembly at the replication fork of phage phi X174. ComFORF3 is 22% identical to Com101, a protein required for genetic competence in Haemophilus influenzae, a naturally competent Gram-negative bacterium. In-frame comFORF1 deletions were 1000-fold deficient in transformability compared to the wild-type, whereas disruptions of the other two ORFs were only five- to 10-fold lower. These observations allow us to hypothesize that the ComFORF1 late gene product plays an essential role during the binding and uptake events involved in Bacillus subtilis transformation.
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PMID:comF, a Bacillus subtilis late competence locus, encodes a protein similar to ATP-dependent RNA/DNA helicases. 841 57

We have determined that the DNA sequence downstream of the well-characterized gonococcal fbp gene contains two open reading frames: one designated fbpB, which encodes a protein proposed to function as a cytoplasmic permease, and one designated fbpC, which encodes a protein proposed to function as a nucleotide-binding protein. The fpbABC operon composes an iron transport system that is homologous to the sfu and hit operons previously reported for Serratia marcescens and Haemophilus influenzae, respectively, and displays elements characteristic of ATP binding cassette transporters. The fpbABC operon differs from these loci in that it is lethal when overexpressed in Escherichia coli.
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PMID:The fbpABC locus of Neisseria gonorrhoeae functions in the periplasm-to-cytosol transport of iron. 860 97

A 0.972-kilobase pair DNA fragment from Streptomyces lividans that induces the production of the blue-pigmented antibiotic actinorhodine in S. lividans when cloned on a multicopy plasmid has led to the isolation of a 4-kilobase pair DNA fragment from Streptomyces coelicolor containing homologous sequence. Computer-assisted analysis of the DNA sequence revealed three putative open reading frames (ORFs), ORF1, ORF2, and ORF3. ORF2 extends beyond the sequenced DNA fragment, and its deduced product shares no similarities with any other known proteins in the data bases. ORF3 is also truncated, and its 41-amino acid C-terminal product is identical to the S. coelicolor adenine phosphoribosyltransferase. The 847-amino acid ORF1 protein, with a predicted molecular mass of 94.2 kDa, strongly resembled the relA and spoT gene products from Escherichia coli and the homologs from Vibrio sp. strain S14, Haemophilus influenzae, Streptococcus equisimilis H46A, and Mycoplasma genitalium. Unlike these proteins, the ORF1 amino acid sequence analysis revealed the presence of a putative ATP/GTP-binding domain. A mutant was generated by deleting most of the ORF1 gene that showed an actinorhodine-nonproducing phenotype, while undecylprodigiosin and the calcium-dependent antibiotic were unaffected. The mutant strain grew at a much lower rate than the wild-type strain, and spore formation was delayed. When the gene was propagated on a low copy number vector, not only was actinorhodine production restored, but actinorhodine and undecylprodigiosin production was enhanced in both the mutant and wild-type and morphological differentiation returned to wild-type characteristics. (p)ppGpp synthetase activity was not detected in purified ribosomes from the ORF1-deleted mutant, while it was restored by complementation of this strain.
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PMID:A relA/spoT homologous gene from Streptomyces coelicolor A3(2) controls antibiotic biosynthetic genes. 863 67

Comparison of subunit AddA of the Bacillus subtilis AddAB enzyme, subunit RecB of the Escherichia coli RecBCD enzyme, and subunit RecB of the Haemophilus influenzae RecBCD enzyme revealed several regions of homology. Whereas the first seven regions are common among helicases, the two C-terminally located regions are unique for RecB of E. coli and H. influenzae and AddA. Deletion of the C-terminal region resulted in the production of an enzyme which showed moderately impaired levels of ATP-dependent helicase activity, whereas the ATP-dependent exonuclease activity was completely destroyed. The mutant enzyme was almost completely capable of complementing E. coli recBCD and B. subtilis addAB strains with respect to DNA repair and homologous recombination. These results strongly suggest that at least part of the C-terminal region of the AddA protein is indispensable for exonuclease activity and that, in contrast to the exonuclease activity, the helicase activity of the addAB gene product is important for DNA repair and homologous recombination.
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PMID:The C terminus of the AddA subunit of the Bacillus subtilis ATP-dependent DNase is required for the ATP-dependent exonuclease activity but not for the helicase activity. 875 23


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