Article

Human and E.coli excinucleases are affected differently by the sequence context of acetylaminofluorene-guanine adduct.

Department of Biochemistry and Biophysics, University of North Carolina, School of Medicine, Chapel Hill.
Nucleic Acids Research (Impact Factor: 8.81). 12/1994; 22(23):4869-71. DOI: 10.1093/nar/22.23.4869
Source: PubMed

ABSTRACT Synthetic DNA substrates containing an acetylaminofluorene (AAF) adduct at each of the three guanine in the G1G2CG3CC sequence were constructed and tested as substrates for reconstituted E.coli (A)BC excinuclease and human excinuclease in HeLa cell-free extract (CFE). The (A)BC excinulcease repaired the three substrates with relative efficiencies of G1:G2:G3 of 100:18:66 in agreement with an earlier report [Seeberg, E., and Fuchs, R.P.P. (1990) Proc. Natl Acad. Sci. USA 87, 191-194]. The same lesions were repaired by the human excinuclease with the strikingly different efficiencies of G1:G2:G3 as 38:100:68. These results reveal that the human excinuclease is affected by the sequence context of the lesion in a different manner than its prokaryotic counterpart.

0 Bookmarks
 · 
46 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: This report revises the use of the maximum energy recovery criterion as objective function for real-time optimisation of heat-exchanger networks. Though in general this criterion leads to minimum total heat exchanged in the service units, it is not sufficient to achieve the actual minimum operation cost. This analysis discusses the characteristics of the network structure for which the last statement is applicable, and proposes an alternative performance index to address more directly the final economic objective for which these heat-recovery systems are created. An application example demonstrates the significant differences in operating conditions that may result from using one or the other criterion, something of outmost importance when defining online optimisation for these systems.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Nucleotide excision repair (NER) removes lesions caused by environmental mutagens or UV light from DNA. A hallmark of NER is the extraordinarily wide substrate specificity, raising the question of how one set of proteins is able to recognize structurally diverse lesions. Two key features of good NER substrates are that they are bulky and thermodynamically destabilize DNA duplexes. To understand what the limiting step in damage recognition in NER is, we set out to test the hypothesis that there is a correlation of the degree of thermodynamic destabilization induced by a lesion, binding affinity to the damage recognition protein XPC-RAD23B and overall NER efficiency. We chose to use acetylaminofluorene (AAF) and aminofluorene (AF) adducts at the C8 position of guanine in different positions within the NarI (GGCGCC) sequence, as it is known that the structures of the duplexes depend on the position of the lesion in this context. We found that the efficiency of NER and the binding affinity of the damage recognition factor XPC-RAD23B correlated with the thermodynamic destabilization induced by the lesion. Our study is the first systematic analysis correlating these three parameters and supports the idea that initial damage recognition by XPC-RAD23B is a key rate-limiting step in NER.
    Chemical Research in Toxicology 10/2012; 25(11). DOI:10.1021/tx3003033 · 4.19 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The environmental arylamine mutagens are implicated in the etiology of various sporadic human cancers. Arylamine-modified dG lesions were studied in two fully paired 11-mer duplexes with a -G*CN- sequence context, in which G* is a C8-substituted dG adduct derived from fluorinated analogs of 4-aminobiphenyl (FABP), 2-aminofluorene (FAF) or 2-acetylaminofluorene (FAAF), and N is either dA or dT. The FABP and FAF lesions exist in a simple mixture of 'stacked' (S) and 'B-type' (B) conformers, whereas the N-acetylated FAAF also samples a 'wedge' (W) conformer. FAAF is repaired three to four times more efficiently than FABP and FAF. A simple A- to -T polarity swap in the G*CA/G*CT transition produced a dramatic increase in syn-conformation and resulted in 2- to 3-fold lower nucleotide excision repair (NER) efficiencies in Escherichia coli. These results indicate that lesion-induced DNA bending/thermodynamic destabilization is an important DNA damage recognition factor, more so than the local S/B-conformational heterogeneity that was observed previously for FAF and FAAF in certain sequence contexts. This work represents a novel 3'-next flanking sequence effect as a unique NER factor for bulky arylamine lesions in E. coli.
    Nucleic Acids Research 11/2012; 41(2). DOI:10.1093/nar/gks1077 · 8.81 Impact Factor

Full-text (3 Sources)

Download
13 Downloads
Available from
Jun 10, 2014