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

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

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

In a study of the quinolone resistance genes in Staphylococcus aureus, a recG homolog was cloned as a gene affecting quinolone susceptibility. Sequencing analysis revealed that the gene consists of 2,061 nucleotides and encodes a 686-amino-acid polypeptide, which shows 38, 39, and 50% amino acid identity with the RecGs of Escherichia coli, Haemophilus influenzae, and Streptococcus pneumoniae, respectively. Seven helicase motifs are well conserved in the gene product. A plasmid carrying the gene complemented a recG-deficient mutant of E. coli with respect to mitomycin hypersusceptibility, demonstrating that the gene product is functionally equivalent to E. coli RecG. These results indicate that the gene is the recG gene of S. aureus. S. aureus RCM101 (recG::Tn551), designated S. aureus 3f33, is four to eight times more susceptible to quinolones than the parent strain, RCM101. The transformation of strain 3f33 with a plasmid carrying the S. aureus recG gene made it as quinolone resistant as strain RCM101. These results suggest that the recG gene is involved in the repair of DNA damage resulting from quinolone treatment in S. aureus.
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PMID:Cloning and sequencing of a novel gene (recG) that affects the quinolone susceptibility of Staphylococcus aureus. 925 58

The Escherichia coli Chi site 5'-GCTGGTGG-3' modulates the activity of the powerful dsDNA exonuclease and helicase RecBCD. Genome sequence analyses revealed that Chi is frequent on the chromosome and oriented with respect to replication on the E. coli genome. Chi is also present much more frequently than predicted statistically for a random 8-mer sequence. Although it is assumed that Chi is ubiquitous, there is virtually no proof that its features are conserved in other microorganisms. We therefore identified and analysed the Chi sequence of an organism for which the full genome sequence was available, Haemophilus influenzae. The biological test we used is based on our finding that rolling circle plasmids provide a specific substrate for RecBCD analogues in different microorganisms. Unexpectedly, several related sequences, corresponding to 5'-GNTGGTGG-3' and 5'-G(G/C)TGGAGG-3', showed Chi activity. As in E. coli, the H. influenzae Chi sites are frequent on the genome, which is in keeping with the need for frequent Chi sites for dsDNA break repair of chromosomal DNA. Although statistically over-represented, this feature is less marked than that of the E. coli Chi site. In contrast to E. coli, the H. influenzae Chi motifs are only slightly oriented with respect to the replication strand. Thus, although Chi appears to have a highly conserved biological role in attenuating exonuclease activity, its sequence characteristics and statistical representation on the genome may differ according to the particular features of the host.
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PMID:Identification of the Chi site of Haemophilus influenzae as several sequences related to the Escherichia coli Chi site. 953 91

Haemophilus influenzae and Helicobacter pylori are major bacterial pathogens that face high levels of genotoxic stress within their host. UvrD, a ubiquitous bacterial helicase that plays important roles in multiple DNA metabolic pathways, is essential for genome stability and might, therefore, be crucial in bacterial physiology and pathogenesis. In this study, the functional characterization of UvrD helicase from Haemophilus influenzae and Helicobacter pylori is reported. UvrD from Haemophilus influenzae (HiUvrD) and Helicobacter pylori (HpUvrD) exhibit strong single-stranded DNA-specific ATPase and 3'-5' helicase activities. Mutation of highly conserved arginine (R288) in HiUvrD and glutamate (E206) in HpUvrD abrogated their activities. Both the proteins were able to bind and unwind a variety of DNA structures including duplexes with strand discontinuities and branches, three- and four-way junctions that underpin their role in DNA replication, repair and recombination. HiUvrD required a minimum of 12 nucleotides, whereas HpUvrD preferred 20 or more nucleotides of 3'-single-stranded DNA tail for efficient unwinding of duplex DNA. Interestingly, HpUvrD was able to hydrolyze and utilize GTP for its helicase activity although not as effectively as ATP, which has not been reported to date for UvrD characterized from other organisms. HiUvrD and HpUvrD were found to exist predominantly as monomers in solution together with multimeric forms. Noticeably, deletion of distal C-terminal 48 amino acid residues disrupted the oligomerization of HiUvrD, whereas deletion of 63 amino acids from C-terminus of HpUvrD had no effect on its oligomerization. This study presents the characteristic features and comparative analysis of Haemophilus influenzae and Helicobacter pylori UvrD, and constitutes the basis for understanding the role of UvrD in the biology and virulence of these pathogens.
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PMID:Functional characterization of UvrD helicases from Haemophilus influenzae and Helicobacter pylori. 2250 May 16