RESUMEN
We have previously reported on cloning a DNA repair gene designated as uvr3 by virtue of its ability to phenotypically complement the UV sensitivity of mutant strain MBH3. Subsequently, we identified the uvr3 gene to be the uvrA gene (gene identification number HI0249) of Haemophilus influenzae Rd. The uvrA gene is a component of the UvrABC excision repair pathway. We studied molecular basis of the UV sensitivity of the MBH3 strain and identified a G-->A transition at nucleotide position 2700 of the uvrA gene, altering the Trp-900 codon (TGG) to a nonsense codon (TGA). Thus, the UvrA protein produced in the mutant strain MBH3 is likely to be truncated and unable to carry out the UV-induced DNA repair, thereby rendering the strain UV sensitive.
Asunto(s)
Adenosina Trifosfatasas , Proteínas Bacterianas , Proteínas de Unión al ADN , Proteínas de Escherichia coli , Haemophilus influenzae/genética , Mutación , Rayos UltravioletaRESUMEN
2,4-Dihydroxybenzophenone (2,4-DHB) imprinted polymers were synthesized by surface imprinting technique, using allyl alcohol as the functional monomer. The polymers showed a very high selectivity for 2,4-DHB when compared with various positional isomers such as 2-HB, 2,2'-DHB, 4,4'-DHIB and 4,4'-DMB. Solvents were found to affect the selectivity as well as sorption capacity in the case of surface imprinted polymers. The selectivities decreased drastically when the imprint cavity was blocked. This validated the importance of the cavity and the rebinding interactions in governing the selectivity in the case of MIPs. The surface imprinted polymers also showed a high selectivity under non-equilibrium conditions thereby making them suitable adsorbents for industrial separations.
Asunto(s)
Benzofenonas/química , Polímeros/química , Cromatografía Líquida de Alta Presión/métodos , Polímeros/síntesis química , Reproducibilidad de los ResultadosRESUMEN
A chimeric plasmid, pJPuvr4, consists of a 16.7 kbp Haemophilus influenzae Rd chromosomal DNA insert at the EcoRI site of vector pJ1-8. This plasmid complements the UV and gamma ray sensitivity of the mutant strain MBH4. This plasmid carries the wild type allele of gene uvr4 which was localised to a 3.8 kbp DraI fragment, with an internal EcoRI site. Partial sequencing of the gene and its alignment with the published genome sequence of H. influenzae Rd revealed uvr4 to be HI1472. HI1472 is a putatively identified open reading frame (ORF), which has been assigned no function so far. The partial sequence did show nt database match with 3D exon of N cadherin gene of homosepians and moaA gene of H. influenzae. Cadherins are involved in cell adhesion, cell to cell contact and morphogenesis in homosepians and moaA gene codes for molybdenum biosynthesis subunitA. This report implicates HI1472 of Haemophilus influenzae Rd in DNA repair. Nucleotide sequence obtained for the gene uvr4 was compared with the published sequence of gene HI1472. A wild type strain variation was observed at the 592nd nucleotide position corresponding to a change from aspartic acid to threonine.
Asunto(s)
Genes Bacterianos , Haemophilus influenzae/genética , Secuencia de Bases , Mapeo Cromosómico , Clonación Molecular , Reparación del ADN/genética , ADN Bacteriano/genética , Haemophilus influenzae/efectos de la radiación , Datos de Secuencia MolecularRESUMEN
Fate of 32P-labelled pJ1-8N19 DNA was followed in the mutant strain N19 and wild type H. influenzae Rd, during post-uptake incubation. Integration of the insert fragment carrying novr gene into the host genome was measured at various time intervals during post-uptake incubation. Negligible amount of label transfer and no detectable transfer of biological activity (novr) was observed in mutant strain N19 compared to wild type strain Rd. These observations correlated poor extra chromosomal establishments of the donor plasmid in the mutant strain N19.
Asunto(s)
Quimera/genética , Haemophilus influenzae/genética , Plásmidos/genética , Transformación BacterianaRESUMEN
A 17.7 kbp EcoR1 fragment of Haemophilus influenzae Rd (wild-type strain) DNA containing repeats has been cloned together with the DNA repair gene uvr3. The region containing repetitive DNA was subcloned on a 13 kbp EcoR1 fragment (pHi13). The insert hybridizes with restriction enzyme digests of H. influenzae Rd and H. parainfluenzae and exhibits a repetitive pattern. Discrete bands superimposed upon a polydisperse background were observed when pHi13 hybridizes with restriction digests of human DNA. The hybridization patterns indicate that H. parainfluenzae and human DNA contain cross-hybridizing sequences. The repeats of pHi13 are present on a 2.6 kbp PvuII fragment.