scholarly journals 5' to 3' Single Strand DNA Exonuclease Activity in a Preparation of Human Ku Protein

IUBMB Life ◽  
1999 ◽  
Vol 48 (6) ◽  
pp. 593-599
Author(s):  
Viktor Morozov ◽  
Brian Fuller
IUBMB Life ◽  
1999 ◽  
Vol 48 (6) ◽  
pp. 593-599
Author(s):  
Viktor E. Morozov ◽  
Brian G. Fuller

1998 ◽  
Vol 180 (4) ◽  
pp. 989-993 ◽  
Author(s):  
Reuben S. Harris ◽  
Kimberly J. Ross ◽  
Mary-Jane Lombardo ◽  
Susan M. Rosenberg

ABSTRACT In vitro, the methyl-directed mismatch repair system ofEscherichia coli requires the single-strand exonuclease activity of either ExoI, ExoVII, or RecJ and possibly a fourth, unknown single-strand exonuclease. We have created the first precise null mutations in genes encoding ExoI and ExoVII and find that cells lacking these nucleases and RecJ perform mismatch repair in vivo normally such that triple-null mutants display normal mutation rates. ExoI, ExoVII, and RecJ are either redundant with another function(s) or are unnecessary for mismatch repair in vivo.


2006 ◽  
Vol 71 (2) ◽  
pp. 200-210 ◽  
Author(s):  
N. S. Dyrkheeva ◽  
S. N. Khodyreva ◽  
M. V. Sukhanova ◽  
I. V. Safronov ◽  
S. V. Dezhurov ◽  
...  

1973 ◽  
Vol 51 (6) ◽  
pp. 888-895 ◽  
Author(s):  
Cecily Mills ◽  
M. J. Fraser

Three fractions with single-strand-specific nuclease activity have been isolated by chromatography on phosphocellulose and hydroxyapatite from Neurospora crassa conidia. Two of the fractions containing, respectively, 9% and 7% of the total nuclease activity recovered had the same chromatographic and enzymological properties as the endonuclease and exonuclease previously reported. The third fraction, containing 84% of the total nuclease activity recovered, was shown to contain a mixture of single-strand-specific endonuclease and exonuclease activities enzymologically indistinguishable from the activities previously described. The two components of this fraction were resolved by polyacrylamide gel electrophoresis. A fraction with the same chromatographic properties was also isolated from N. crassa mycelia in which single-strand-specific endonuclease, but no exonuclease activity, was detected. The two mycelial endonuclease fractions were enzymologically indistinguishable. The results were shown not to be due to artifacts of chromatography. Different batches of N. crassa conidia have been found to be heterogeneous with respect to contents of endonuclease and exonuclease.


2019 ◽  
Vol 48 (4) ◽  
pp. 1925-1940 ◽  
Author(s):  
Yunfeng Lin ◽  
Jude Raj ◽  
Jia Li ◽  
Anh Ha ◽  
Md Akram Hossain ◽  
...  

Abstract DNA single-strand breaks (SSBs) represent the most abundant type of DNA damage. Unrepaired SSBs impair DNA replication and transcription, leading to cancer and neurodegenerative disorders. Although PARP1 and XRCC1 are implicated in the SSB repair pathway, it remains unclear how SSB repair and SSB signaling pathways are coordinated and regulated. Using Xenopus egg extract and in vitro reconstitution systems, here we show that SSBs are first sensed by APE1 to initiate 3′–5′ SSB end resection, followed by APE2 recruitment to continue SSB end resection. Notably, APE1’s exonuclease activity is critical for SSB repair and SSB signaling pathways. An APE1 exonuclease-deficient mutant identified in somatic tissue from a cancer patient highlighted the significance of APE1 exonuclease activity in cancer etiology. In addition, APE1 interacts with APE2 and PCNA, although PCNA is dispensable for APE1’s exonuclease activity. Taken together, we propose a two-step APE1/APE2-mediated mechanism for SSB end resection that couples DNA damage response with SSB repair in a eukaryotic system.


2020 ◽  
Author(s):  
Di Liu ◽  
Yaming Shao ◽  
Joseph A. Piccirilli ◽  
Yossi Weizmann

<p>Though advances in nanotechnology have enabled the construction of synthetic nucleic acid based nanoarchitectures with ever-increasing complexity for various applications, high-resolution structures are lacking due to the difficulty of obtaining good diffracting crystals. Here we report the design of RNA nanostructures based on homooligomerizable tiles from an RNA single-strand for X-ray determination. Three structures are solved to near-atomic resolution: a 2D parallelogram, an unexpectedly formed 3D nanobracelet, and a 3D nanocage. Structural details of their constituent motifs—such as kissing loops, branched kissing-loops and T-junctions—that resemble natural RNA motifs and resisted X-ray determination are revealed. This work unveils the largely unexplored potential of crystallography in gaining high-resolution feedback for nanostructure design and suggests a novel route to investigate RNA motif structures by configuring them into nanoarchitectures.</p>


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