Specific Incorporation of an Artificial Nucleotide Opposite a Mutagenic DNA Adduct by a DNA Polymerase
摘要:
The ability to detect DNA modification sites at single base resolution could significantly advance studies regarding DNA adduct levels, which are extremely difficult to determine. Artificial nucleotides that are specifically incorporated opposite a modified DNA site offer a potential strategy for detection of such sites by DNA polymerase-based systems. Here we investigate the action of newly synthesized base-modified benzimidazole-derived 2'-deoxynucleoside-5'-O-triphosphates on DNA polymerases when performing translesion DNA synthesis past the pro-mutagenic DNA adduct O-6-benzylguanine (O6-BnG). We found that a mutated form of KlenTaq DNA polymerase, i.e., KTqM747K, catalyzed O6-BnG adduct-specific processing of the artificial BenziTP in favor of the natural dNTPs. Steady-state kinetic parameters revealed that KTqM747K catalysis of BenziTP is 25-fold more efficient for template O-6-BnG than G, and 5-fold more efficient than natural dTMP misincorporation in adduct bypass. Furthermore, the nucleotide analogue BenziTP is required for full-length product formation in O-6-BnG bypass, as without BenziTP the polymerase stalls at the adduct site. By combining the KTqM747K polymerase and BenziTP, a first round of DNA synthesis enabled subsequent amplification of Benzi-containing DNA. These results advance the development of technologies for detecting DNA adducts.
Enzymatic Synthesis of Therapeutic Nucleosides using a Highly Versatile Purine Nucleoside 2’‐DeoxyribosylTransferase from<i>Trypanosoma brucei</i>
作者:Elena Pérez、Pedro A. Sánchez‐Murcia、Justin Jordaan、María Dolores Blanco、José Miguel Mancheño、Federico Gago、Jesús Fernández‐Lucas
DOI:10.1002/cctc.201800775
日期:2018.10.9
selected as the best derivative (4200 IU/g, activity recovery of 22 %), and could be easily recaptured and recycled for >25 reactions with negligible loss of activity. Finally, MTbPDT3 was successfully employed in the expedient synthesis of several nucleoside analogues. Taken together, our results support the notion that TbPDT has good potential as an industrial biocatalyst for the synthesis of a wide range
与多步化学方法相比,使用酶来合成核苷类似物具有多个优势,包括化学,区域和立体选择性以及较温和的反应条件。本文报道了来自布鲁氏锥虫的嘌呤核苷2'-脱氧核糖基转移酶(PDT)的生产,表征和利用。Tb PDT是一种二聚体,不仅在很宽的温度范围(50–70°C),pH(4–7)和离子强度(0–500 mM NaCl)范围内都显示出出色的活性和稳定性,而且在高温下具有非凡的高稳定性碱性条件(pH 8-10)。bPDT被证明可以熟练地合成许多治疗性核苷,包括去羟肌苷,维达拉滨,克拉屈滨,氟达拉滨和奈拉拉滨。用Ala或Ser进行结构指导的Val11置换,导致变体的活性提高了2.8倍。Tb PDT也共价固定在戊二醛激活的磁性微球上。选择了M Tb PDT3作为最佳衍生物(4200 IU / g,活性回收率为22%),可以轻松地将其重新捕获和再循环用于> 25个反应,而活性损失可忽略不计。最后,男铽PDT3
Introduction of pseudo-base benzimidazole derivatives into nucleosides via base exchange by a nucleoside metabolic enzyme
organic synthesis, biocatalysis using enzymes provides a more stereoselective and cost-effective approach. Synthesis of unnatural nucleosides by nucleoside base exchange reactions using nucleoside-metabolizing enzymes has previously shown that the 5-position recognition of pyrimidine bases on nucleoside substrates is loose and can be used to introduce functional molecules into pyrimidine nucleosides. Here
<i>Aeromonas hydrophila</i>strains as biocatalysts for transglycosylation
作者:Matías Nóbile、Marco Terreni、Elizabeth Lewkowicz、Adolfo M. Iribarren
DOI:10.3109/10242422.2010.538949
日期:2010.12
Microbial transglycosylation is useful as a green alternative in the preparation of purine nucleosides and analogues, especially for those that display pharmacological activities. In a search for new transglycosylation biocatalysts, two Aeromonas hydrophila strains were selected. The substrate specificity of both micro-organisms was studied and, as a result, several nucleoside analogues have been prepared. Among them, ribavirin, a broad spectrum antiviral, and the well-known anti HIV didanosine, were prepared, in 77 and 62% yield using A. hydrophila CECT 4226 and A. hydrophila CECT 4221, respectively. In order to scale-up the processes, the reaction conditions, product purification and biocatalyst preparation were analyzed and optimized.
Use of Citrobacter koseri whole cells for the production of arabinonucleosides: A larger scale approach
作者:Matías Nóbile、Rosario Médici、Marco Terreni、Elizabeth S. Lewkowicz、Adolfo M. Iribarren
DOI:10.1016/j.procbio.2012.08.011
日期:2012.12
Purine arabinosides are well known antiviral and antineoplastic drugs. Since their chemical synthesis is complex, time-consuming, and polluting, enzymatic synthesis provides an advantageous alternative. In this work, we describe the microbial whole cell synthesis of purine arabinosides through nucleoside phosphorylase-catalyzed transglycosylation starting from their pyrimidine precursors. By screening of our microbial collection, Citrobacter koseri (CECT 856) was selected as the best biocatalyst for the proposed biotransformation. In order to enlarge the scale of the transformations to 150 mL for future industrial applications, the biocatalyst immobilization by entrapment techniques and its behavior in different reactor configurations, considering both batch and continuous processes, were analyzed. C koseri immobilized in agarose could be used up to 68 times and the storage stability was at least 9 months. By this approach, fludarabine (58% yield in 14h), vidarabine (71% yield in 26h) and 2,6-diaminopurine arabinoside (77% yield in 24h), were prepared. (C) 2012 Elsevier Ltd. All rights reserved.
Tolerance of Base Pair Size and Shape in Postlesion DNA Synthesis
作者:Hailey L. Gahlon、W. Bernd Schweizer、Shana J. Sturla
DOI:10.1021/ja311434s
日期:2013.5.1
The influence of base pair size and shape on the fidelity of DNA polymerase-mediated extension past lesion-containing mispairs was examined. Primer extension analysis was performed with synthetic nucleo-sides paired opposite the pro-mutagenic DNA lesion O-6-benzylguanine (O-6-BnG). These data,indicate that the error prone DNA polymerase IV (Dpo4) inefficiently extended past the larger Peri:O-6-BnG base pair, and in contrast, error free extension was observed for the smaller BIM:O-6-BnG base pair. Steady-state kinetic analysis, revealed that Dpo4 catalytic efficiency was strongly influenced by the primer:template base pair. Compared to the C:G pair, a 1.9- and 79 000-fold reduction in Dpo4 efficiency was observed for terminal C:O-6-BnG and BIM:G base pairs respectively. These results demonstrate the impact of geometrical size and shape on polymerase-mediated mispair extension.