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Efficient and error-free replication past a minor-groove DNA adduct by the sequential action of human DNA polymerases iota and kappa
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Washington MT Minko IG Johnson RE Wolfle WT Harris TM Lloyd RS Prakash S Prakash L 《Molecular and cellular biology》2004,24(13):5687-5693
DNA polymerase iota (Poliota) is a member of the Y family of DNA polymerases, which promote replication through DNA lesions. The role of Poliota in lesion bypass, however, has remained unclear. Poliota is highly unusual in that it incorporates nucleotides opposite different template bases with very different efficiencies and fidelities. Since interactions of DNA polymerases with the DNA minor groove provide for the nearly equivalent efficiencies and fidelities of nucleotide incorporation opposite each of the four template bases, we considered the possibility that Poliota differs from other DNA polymerases in not being as sensitive to distortions of the minor groove at the site of the incipient base pair and that this enables it to incorporate nucleotides opposite highly distorting minor-groove DNA adducts. To check the validity of this idea, we examined whether Poliota could incorporate nucleotides opposite the gamma-HOPdG adduct, which is formed from an initial reaction of acrolein with the N(2) of guanine. We show here that Poliota incorporates a C opposite this adduct with nearly the same efficiency as it does opposite a nonadducted template G residue. The subsequent extension step, however, is performed by Polkappa, which efficiently extends from the C incorporated opposite the adduct. Based upon these observations, we suggest that an important biological role of Poliota and Polkappa is to act sequentially to carry out the efficient and accurate bypass of highly distorting minor-groove DNA adducts of the purine bases. 相似文献
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Anne S Rasmussen Henrik Lauridsen Christoffer Laustsen Bjarke G Jensen Steen F Pedersen Lars Uhrenholt Lene WT Boel Niels Uldbjerg Tobias Wang Michael Pedersen 《BMC physiology》2010,10(1):3
Background
In biomedical sciences, ex vivo angiography is a practical mean to elucidate vascular structures three-dimensionally with simultaneous estimation of intravascular volume. The objectives of this study were to develop a magnetic resonance (MR) method for ex vivo angiography and to compare the findings with computed tomography (CT). To demonstrate the usefulness of this method, examples are provided from four different tissues and species: the human placenta, a rice field eel, a porcine heart and a turtle. 相似文献6.
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Paralogous origin of the red- and green-sensitive visual pigment genes in vertebrates 总被引:1,自引:0,他引:1
The nucleotide sequence of the red-sensitive visual pigment gene, R007Af,
in the fish Astyanax fasciatus, from the initiation codon to the stop codon
of this gene, including introns, is 1,592 bp, making it the shortest visual
pigment gene known in vertebrates. Analysis of this and other homologous
sequence data suggests that vertebrates initially had two duplicate genes
and that each ancestor of Astyanax, human, and chicken independently
duplicated the gene in the process of developing their red-green color
vision. Furthermore, many extant red-green colorblind organisms may be
explained simply by the failure of achieving very specific nucleotide
substitutions at the three codon positions 180, 277, and 285, rather than
by the lack of duplicate loci.
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Unusual molecular evolution of an Adh pseudogene in Drosophila 总被引:2,自引:0,他引:2
Sullivan DT; Starmer WT; Curtiss SW; Menotti-Raymond M; Yum J 《Molecular biology and evolution》1994,11(3):443-458
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Supramolecular structures of peptide assemblies in membranes by neutron off-plane scattering: method of analysis 总被引:2,自引:1,他引:1
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In a previous paper (Yang et al., Biophys. J. 75:641-645, 1998), we showed a simple, efficient method of recording the diffraction patterns of supramolecular peptide assemblies in membranes where the samples were prepared in the form of oriented multilayers. Here we develop a method of analysis based on the diffraction theory of two-dimensional liquids. Gramicidin was used as a prototype model because its pore structure in membrane in known. At full hydration, the diffraction patterns of alamethicin and magainin are similar to gramicidin except in the scale of q (the momentum transfer of scattering), clearly indicating that both alamethicin and magainin form pores in membranes but of different sizes. When the hydration of the multilayer samples was decreased while the bilayers were still fluid, the in-plane positions of the membrane pores became correlated from one bilayer to the next. We believe that this is a new manifestation of the hydration force. The effect is most prominent in magainin patterns, which are used to demonstrate the method of analysis. When magainin samples were further dehydrated or cooled, the liquid-like diffraction turned into crystal-like patterns. This discovery points to the possibility of investigating the supramolecular structures with high-order diffraction. 相似文献