EM measurements define the dimensions of the "30-nm" chromatin fiber: evidence for a compact, interdigitated structure.

ABSTRACT: Chromatin structure plays a fundamental role in the regulation of nuclear processes such as DNA transcription, replication, recombination, and repair. Despite considerable efforts during three decades, the structure of the 30-nm chromatin fiber remains controversial. To define fiber dimensions accurately, we have produced very long and regularly folded 30-nm fibers from in vitro reconstituted nucleosome arrays containing the linker histone and with increasing nucleosome repeat lengths (10 to 70 bp of linker DNA). EM measurements show that the dimensions of these fully folded fibers do not increase linearly with increasing linker length, a finding that is inconsistent with two-start helix models. Instead, we find that there are two distinct classes of fiber structure, both with unexpectedly

SUBMITTER: Robinson PJ 

PROVIDER: S-EPMC1436021 | biostudies-literature | 2006 Apr

REPOSITORIES: biostudies-literature