DNA PACKAGING INDUCED BY MICELLAR AGGREGATES - A NOVEL INVITRO DNA CONDENSATION SYSTEM

被引:97
作者
GHIRLANDO, R
WACHTEL, EJ
ARAD, T
MINSKY, A
机构
[1] WEIZMANN INST SCI,DEPT ORGAN CHEM,IL-76100 REHOVOT,ISRAEL
[2] WEIZMANN INST SCI,DEPT STRUCT BIOL,IL-76100 REHOVOT,ISRAEL
[3] WEIZMANN INST SCI,CHEM SERV UNIT,IL-76100 REHOVOT,ISRAEL
关键词
D O I
10.1021/bi00146a012
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
Evidence for a conceptually novel DNA packaging process is presented. X-ray scattering, electron microscopy, and circular dichroism measurements indicate that in the presence of positively charged micellar aggregates and flexible anionic polymers, such as negatively charged polypeptides or single-stranded RNA species, a complex is formed in which DNA molecules are partially embedded within a micellar scaffold and partially condensed into highly packed chiral structures. Based on studies of micelle-DNA and micelle-flexible anionic polymer systems, as well as on the known effects of a high charge density upon the micellar organization, a DNA packaging model is proposed. According to this model, the DNA induces the elongation of the micelles into rodlike aggregates, forming a closely packed matrix in which the DNA molecules are immobilized. In contrast, the flexible anionic polymers stabilize clusters of spherical micelles which are proposed to effect a capping of the rodlike micelles, thus arresting their elongation and creating surfactant-free segments of the DNA that are able to converge and collapse. Thus, unlike other in vitro DNA packaging systems, in which condensation follows encounters between charge-neutralized DNA molecules, a prepackaging phase where the DNA is immobilized within a matrix is proposed in this case. Cellular and nuclear membranes have been implicated in DNA packaging processes in vivo, and negatively charged polyelectrolytes were shown to be involved in the processes. These observations, combined with the basic tenets of the DNA condensation system described here, allow for the progression to the study of more elaborate model systems and thus might lead to insights into the nature and roles of the intricate in vivo DNA-membrane complexes.
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页码:7110 / 7119
页数:10
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