Voitkun V, Zhitkovich A
Department of Pathology and Laboratory Medicine, Brown University, Box G-B511, Providence, RI 02912, USA.
Mutat Res. 1999 Mar 8;424(1-2):97-106. doi: 10.1016/s0027-5107(99)00011-1.
In an attempt to identify endogenous chemicals producing DNA-protein crosslinks, we have studied in vitro crosslinking potential of malondialdehyde, a bifunctional chemical that is ubiquitously formed as a product of lipid peroxidation of polyunsaturated fatty acids. We have found that malondialdehyde readily forms crosslinks between DNA and histones under physiological ionic and pH conditions. Formation of DNA-protein crosslinks was limited to proteins that were able to bind to DNA. Malondialdehyde failed to form DNA-protein crosslinks when histone binding to DNA was prevented by elevated ionic strength or when bovine serum albumin was used in the reaction mixture. Malondialdehyde-produced DNA-histone crosslinks were relatively stable at 37 degrees C with t1/2=13.4 days. Crosslinking of histones to DNA proceeds through the initial formation of protein adduct followed by reaction with DNA. Modification of DNA by malondialdehyde does not lead to a subsequent crosslinking of proteins. Significant formation of DNA-protein crosslinks was also registered in isolated kidney and liver nuclei treated with malondialdehyde. Based on its reactivity and stability of the resulting crosslinks, it is suggested that malondialdehyde could be one of the significant sources of endogenous DNA-protein crosslinks.
为了鉴定产生DNA-蛋白质交联的内源性化学物质，我们研究了丙二醛的体外交联潜力，丙二醛是一种双功能化学物质，作为多不饱和脂肪酸脂质过氧化的产物普遍形成。我们发现，在生理离子和pH条件下，丙二醛很容易在DNA和组蛋白之间形成交联。DNA-蛋白质交联的形成仅限于能够与DNA结合的蛋白质。当通过提高离子强度阻止组蛋白与DNA结合时，或当在反应混合物中使用牛血清白蛋白时，丙二醛未能形成DNA-蛋白质交联。丙二醛产生的DNA-组蛋白交联在37℃下相对稳定，半衰期为13.4天。组蛋白与DNA的交联通过蛋白质加合物的初始形成，然后与DNA反应进行。丙二醛对DNA的修饰不会导致随后蛋白质的交联。在用丙二醛处理的分离的肾和肝细胞核中也记录到了显著的DNA-蛋白质交联形成。基于其反应性和所得交联的稳定性，提示丙二醛可能是内源性DNA-蛋白质交联的重要来源之一。
