低离子强度下核小体核心结构的小角中子散射研究

Small angle neutron scattering studies of the structure of nucleosome cores at low ionic strength.

作者信息

Mita K, Zama M, Ichimura S, Niimura N, Kaji K, Hirai M, Ishikawa Y

出版信息

Nucleic Acids Symp Ser. 1982(11):185-8.

PMID:6820813

Abstract

Nucleosome core particles from chicken erythrocytes have been studied by small angle neutron scattering over the range from 10 to 0.04 mM Na+ at 65 and 100% D2O, and the radii of gyration of the particle were determined. A single transition in the radius of gyration was observed at either D2O concentration. With decreasing the ionic strength from 10 mM, the radius of gyration of the histones obtained at 65% D2O increased from 35 to 40A at about 1 mM ionic strength, whereas at 100% D2O the radius of gyration decreased from 39 to 36A also near 1 mM ionic strength. No loss of the secondary structure of the histones was observed by circular dichroism over the range of the ionic strength examined. These results suggest that at low ionic strength (less than or equal to 1 mM) the histones may locate outside of the nucleosome core particle accompanied by an alteration of the tertiary and/or the quaternary structure of the histone octamer.

摘要

利用小角中子散射技术，在65%和100% D₂O条件下，研究了鸡红细胞核小体核心颗粒在10至0.04 mM Na⁺浓度范围内的情况，并测定了颗粒的回转半径。在任一D₂O浓度下，均观察到回转半径的单一转变。随着离子强度从10 mM降低，在65% D₂O条件下获得的组蛋白回转半径在离子强度约为1 mM时从35 Å增加到40 Å，而在100% D₂O条件下，回转半径在离子强度接近1 mM时也从39 Å降低到36 Å。在所研究的离子强度范围内，通过圆二色性未观察到组蛋白二级结构的丧失。这些结果表明，在低离子强度（小于或等于1 mM）下，组蛋白可能位于核小体核心颗粒外部，同时伴随着组蛋白八聚体三级和/或四级结构的改变。