Real-time observation of nucleoplasmin-mediated DNA decondensation and condensation reveals its specific functions as a chaperone

Publication date: August 2018Source: Biochimica et Biophysica Acta (BBA) - Gene Regulatory Mechanisms, Volume 1861, Issue 8Author(s): Xin-Mei Huo, Li-feng Meng, Tao Jiang, Ming Li, Fang-Zhen Sun, Bo Sun, Jian-Ke LiAbstractFertilization requires decondensation of promatine-condensed sperm chromatin, a dynamic process serving as an attractive system for the study of chromatin reprogramming. Nucleoplasmin is a key factor in regulating nucleosome assembly as a chaperone during fertilization process. However, knowledge on nucleoplasmin in chromatin formation remains elusive. Herein, magnetic tweezers (MT) and a chromatin assembly system were used to study the nucleoplasmin-mediated DNA decondensation/condensation at the single-molecular level in vitro. We found that protamine induces DNA condensation in a stepwise manner. Once DNA was condensed, nucleoplasmin, polyglutamic acid, and RNA could remove protamine from the DNA at different rates. The affinity binding of the different polyanions with protamine suggests chaperone-mediated chromatin decondensation activity occurs through protein–protein interactions. After decondensation, both RNA and polyglutamic acid prevented the transfer of histones onto the naked DNA. In contrast, nucleoplasmin is able to assist the histone transfer process, even though it carries the same negative charge as RNA and polyglutamic acid. These observations imply that the chaperone effects of nucleoplasmin during the decondensation/condensation process...

Source: Biochimica et Biophysica Acta (BBA) Gene Regulatory Mechanisms - July 21, 2018 Category: Genetics & Stem Cells Source Type: research