r*****t
发帖数: 4793 | 1 Nature. 2012 Mar 14;483(7390):434-8. doi: 10.1038/nature10895.
Intrinsic coupling of lagging-strand synthesis to chromatin assembly.
Smith DJ, Whitehouse I.
Source
Molecular Biology Program, Memorial Sloan-Kettering Cancer Center, 1275 York
Avenue, New York, New York 10065, USA.
Abstract
Fifty per cent of the genome is discontinuously replicated on the lagging
strand as Okazaki fragments. Eukaryotic Okazaki fragments remain poorly
characterized and, because nucleosomes are rapidly deposited on nascent DNA,
Okazaki fragment processing and nucleosome assembly potentially affect one
another. Here we show that ligation-competent Okazaki fragments in
Saccharomyces cerevisiae are sized according to the nucleosome repeat. Using
deep sequencing, we demonstrate that ligation junctions preferentially
occur near nucleosome midpoints rather than in internucleosomal linker
regions. Disrupting chromatin assembly or lagging-strand polymerase
processivity affects both the size and the distribution of Okazaki fragments
, suggesting a role for nascent chromatin, assembled immediately after the
passage of the replication fork, in the termination of Okazaki fragment
synthesis. Our studies represent the first high-resolution analysis--to our
knowledge--of eukaryotic Okazaki fragments in vivo, and reveal the
interconnection between lagging-strand synthesis and chromatin assembly. | r*****t
发帖数: 4793 | 2 and this one
Wiley Interdiscip Rev RNA. 2011 Nov 15. doi: 10.1002/wrna.113. [Epub ahead
of print]
Diversity of animal small RNA pathways and their biological utility.
Okamura K.
Source
Department of Developmental Biology, Sloan-Kettering Institute, New York, NY
, USA. o******[email protected].
Abstract
Higher eukaryotes employ extensive post-transcriptional gene regulation to
accomplish fine control of gene expression. The microRNA (miRNA) family
plays important roles in the post-transcriptional gene regulation of broad
networks of target mRNA expression. Most miRNAs are generated by a conserved
mechanism involving two RNase III enzymes Drosha and Dicer. However, work
from the past few years has uncovered diverse noncanonical miRNA pathways,
which exploit a variety of other RNA processing enzymes. In addition, the
discovery of another abundant small RNA family, endogenous short interfering
RNAs (endo-siRNAs), has also broadened the catalogs of short regulatory
RNAs. This review highlights recent studies that revealed novel small RNA
biogenesis pathways, and discusses their relevance to gene regulatory
networks. WIREs RNA 2011. doi: 10.1002/wrna.113 For further resources
related to this article, please visit the WIREs website. | a*l
发帖数: 2685 | |
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