中國(guó)科學(xué)院生態(tài)環(huán)境研究中心環(huán)境化學(xué)與生態(tài)毒理國(guó)家重點(diǎn)實(shí)驗(yàn)室汪海林研究員與加拿大阿爾伯塔大學(xué)Chris Le和Michael Weinfeld教授合作發(fā)現(xiàn)一種測(cè)定DNA構(gòu)象變化的新方法,，并以此為基礎(chǔ),，揭示了一種DNA修復(fù)機(jī)制,。該研究成果的詳細(xì)論文發(fā)表在2009年6月15日出版的美國(guó)《國(guó)家科學(xué)院院刊》（PNAS）上。
該研究是一項(xiàng)多學(xué)科的交叉研究,，國(guó)際間的緊密合作為研究的成功提供了可能,。除了以上介紹的生物分析和分子毒理研究方面專家，還獲得在生物化學(xué)和生物物理方面研究者的支持,，如美國(guó)國(guó)立環(huán)境健康研究所的Bennett Van Houten博士,、紐約大學(xué)的Eric Tang博士和蒙大拿大學(xué)的Alexander Ross博士。
人和其他生物常暴露于多種可造成DNA損傷的化學(xué)和物理試劑,，如紫外光,、多環(huán)芳烴、重金屬元素,。如果損傷未能得到適當(dāng)?shù)男迯?fù),，可引起基因突變，并有可能進(jìn)一步引發(fā)癌癥或造成細(xì)胞死亡,。幸運(yùn)的是,，雖然我們每天經(jīng)歷DNA損傷但并不一定會(huì)發(fā)展成為癌癥。這種幸運(yùn)很大程度上來(lái)自于奇妙的DNA修復(fù)功能,，保護(hù)我們的細(xì)胞防止突變,。令人驚奇的是，同一DNA修復(fù)蛋白可識(shí)別并修復(fù)許多化學(xué)結(jié)構(gòu)不同的DNA損傷,。DNA修復(fù)分子是如何高效率地工作,？這一謎團(tuán)的解開(kāi)將有助于癌癥的預(yù)防和治療，因此在世界范圍內(nèi)科學(xué)家們開(kāi)展廣泛的研究,。
為實(shí)現(xiàn)對(duì)DNA損傷的修復(fù),，細(xì)胞利用一組蛋白質(zhì)結(jié)合于損傷位點(diǎn)，適當(dāng)?shù)厍谐瑩p傷的一段寡脫氧核苷酸,，并合成新的片斷填補(bǔ)空白,。修復(fù)后的DNA可恢復(fù)到以前的狀態(tài)。在修復(fù)過(guò)程中,，發(fā)生許多復(fù)雜但受到良好控制的酶反應(yīng),。
最新研究將有助于解釋一些修復(fù)蛋白是如何展示它們可識(shí)別多種損傷的獨(dú)特能力。研究人員研究了與人修復(fù)相似的大腸桿菌(E.coli)修復(fù)通路,，該修復(fù)通路可修復(fù)紫外和許多致癌性化合物引起的DNA損傷,。研究發(fā)現(xiàn)在修復(fù)的早期過(guò)程中,，一種蛋白可將損傷的DNA纏繞于另一種重要的蛋白。DNA纏繞可局部融解DNA的雙螺旋結(jié)構(gòu),，使修復(fù)酶可接觸到損傷部位,。
該項(xiàng)DNA修復(fù)研究工作源于汪海林博士的偶然發(fā)現(xiàn)。最初的設(shè)想是利用DNA修復(fù)酶作為親和探針發(fā)展同時(shí)檢測(cè)多種DNA損傷的分析方法,。在研究中,，汪海林博士意外地發(fā)現(xiàn)一種DNA修復(fù)酶與熒光標(biāo)記的損傷DNA作用可產(chǎn)生非分子量依賴的高熒光偏振響應(yīng)。為解釋這一特殊現(xiàn)象,，汪海林博士設(shè)計(jì)多種DNA探針和實(shí)驗(yàn)，證明了這種高熒光偏振響應(yīng)與DNA纏繞相關(guān),。在Chris Le和Michael Weinfeld教授支持下,，汪海林博士將課題轉(zhuǎn)向修復(fù)機(jī)制的研究。利用新發(fā)現(xiàn)的熒光偏振特性,，揭示了DNA修復(fù)機(jī)器可識(shí)別多種不同化學(xué)結(jié)構(gòu)DNA損傷的機(jī)制,。（生物谷Bioon.com）
生物谷推薦原始出處：
PNAS June 22, 2009, doi: 10.1073/pnas.0902281106
DNA wrapping is required for DNA damage recognition in the Escherichia coli DNA nucleotide excision repair pathway
Hailin Wanga,b, Meiling Lua, Moon-shong Tangc, Bennett Van Houtend,1, J. B. Alexander Rosse, Michael Weinfeldf,2 and X. Chris Lea,2
aDepartment of Laboratory Medicine and Pathology, University of Alberta, Edmonton, AB, Canada T6G 2G3;
bState Key Laboratory of Environmental Chemistry and Ecotoxicology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China;
cDepartment of Environmental Medicine, New York University, Tuxedo, NY 10987;
dNational Institute of Environmental Health Sciences, Research Triangle Park, NC 27709;
eDepartment of Chemistry and Biochemistry and BioSpectroscopy Core Research Laboratory, University of Montana, Missoula, MT 59812; and
fExperimental Oncology, Cross Cancer Institute, Edmonton, AB, Canada T6G 1Z2
Localized DNA melting may provide a general strategy for recognition of the wide array of chemically and structurally diverse DNA lesions repaired by the nucleotide excision repair (NER) pathway. However, it is not clear what causes such DNA melting and how it is driven. Here, we show a DNA wrapping–melting model supported by results from dynamic monitoring of the key DNA–protein and protein–protein interactions involved in the early stages of the Escherichia coli NER process. Using an analytical technique involving capillary electrophoresis coupled with laser-induced fluorescence polarization, which combines a mobility shift assay with conformational analysis, we demonstrate that DNA wrapping around UvrB, mediated by UvrA, is an early event in the damage-recognition process during E. coli NER. DNA wrapping of UvrB was confirmed by F?rster resonance energy transfer and fluorescence lifetime measurements. This wrapping did not occur with readily denaturable damaged DNA substrates (“bubble” DNA), suggesting that DNA wrapping of UvrB plays an important role in the induction of DNA melting around the damage site. Analysis of DNA wrapping of mutant UvrB Y96A further suggests that a cooperative interaction between DNA wrapping of UvrA2B and contact of the β-hairpin of UvrB with the bulky damage moiety may be involved in the local DNA melting at the damage site.
