scholarly journals Baculovirus Alkaline Nuclease Possesses a 5′→3′ Exonuclease Activity and Associates with the DNA-Binding Protein LEF-3

2003 ◽  
Vol 77 (4) ◽  
pp. 2436-2444 ◽  
Author(s):  
Victor S. Mikhailov ◽  
Kazuhiro Okano ◽  
George F. Rohrmann
Keyword(s):  
Dna Binding ◽  
Homologous Recombination ◽  
Binding Protein ◽  
Recombinant Baculovirus ◽  
Dna Binding Protein ◽  
Exonuclease Activity ◽  
Reading Frame ◽  
Ssdna Binding ◽  
Recombination System ◽  
Alkaline Nuclease

ABSTRACT Alkaline nuclease (AN) of the Autographa californica multiple-capsid nucleopolyhedrovirus (AcMNPV) (open reading frame 133) was expressed in recombinant baculovirus as a His6-tagged fusion and purified by sequential chromatography on Ni-NTA-agarose, DEAE-Toyopearl, and heparin-Sepharose. At all stages of purification, AcMNPV AN was found to copurify with a 44-kDa polypeptide which was identified as the baculovirus single-stranded DNA (ssDNA)-binding (SSB) protein, LEF-3. Sedimentation analysis in glycerol gradients of highly purified samples suggested that AN and LEF-3 are associated in a complex (designated *AN/L3), predominantly as heterodimers, although oligomeric forms containing both proteins were evident. In reactions with single- or double-stranded 62-mer oligonucleotides that were labeled with 32P at the 5′ or 3′ ends, *AN/L3 carried out exonucleolytic hydrolysis of both substrates exclusively in a 5′→3′ direction. Saturation of ssDNA with an excess of LEF-3 prior to the addition of *AN/L3 resulted in a marked decrease in the rate of ssDNA hydrolysis. This suggests that excess LEF-3 may protect ssDNA from digestion by a AN-LEF-3 complex, thus regulating its activity in infected cells. The association of baculovirus AN with the viral SSB LEF-3 and the 5′→3′ exonuclease activity of this complex suggests that AN and LEF-3 may participate in homologous recombination of the baculovirus genome in a manner similar to that of exonuclease (Redα) and DNA-binding protein (Redβ) of the Red-mediated homologous recombination system of bacteriophage λ.

scholarly journals REB1, a yeast DNA-binding protein with many targets, is essential for growth and bears some resemblance to the oncogene myb.

1990 ◽  
Vol 10 (10) ◽  
pp. 5226-5234 ◽  
Author(s):  
Q D Ju ◽  
B E Morrow ◽  
J R Warner
Keyword(s):  
Amino Acids ◽  
Dna Binding ◽  
Rna Polymerase Ii ◽  
Essential Gene ◽  
Binding Protein ◽  
Consensus Sequence ◽  
Physiological Role ◽  
Dna Binding Protein ◽  
Reading Frame ◽  
Chromosome Ii

REB1 is a DNA-binding protein that recognizes sites within both the enhancer and the promoter of rRNA transcription as well as upstream of many genes transcribed by RNA polymerase II. We report here the cloning of the gene for REB1 by screening a yeast genomic lambda gt11 library with specific oligonucleotides containing the REB1 binding site consensus sequence. The REB1 gene was sequenced, revealing an open reading frame encoding 809 amino acids. The predicted protein was highly hydrophilic, with numerous OH-containing amino acids and glutamines, features common to many of the general DNA-binding proteins of Saccharomyces cerevisiae, such as ABF1, RAP1, GCN4, and HSF1. There was some homology between a portion of REB1 and the DNA-binding domain of the oncogene myb. REB1 is an essential gene that maps on chromosome II. However, the physiological role that it plays in the cell has yet to be established.

Single-Stranded DNA-Binding Protein Complex from Helicobacter pylori Suggests an ssDNA-Binding Surface

2009 ◽  
Vol 388 (3) ◽  
pp. 508-519 ◽  
Author(s):  
Kun-Wei Chan ◽  
Yi-Juan Lee ◽  
Chia-Hung Wang ◽  
Haimei Huang ◽  
Yuh-Ju Sun
Keyword(s):  
Helicobacter Pylori ◽  
Dna Binding ◽  
Protein Complex ◽  
Binding Protein ◽  
Dna Binding Protein ◽  
Single Stranded Dna ◽  
Ssdna Binding ◽  
Binding Surface

scholarly journals Single-Stranded DNA-Binding Protein and Exogenous RecBCD Inhibitors Enhance Phage-Derived Homologous Recombination in Pseudomonas

iScience ◽  
2019 ◽  
Vol 14 ◽  
pp. 1-14 ◽  
Author(s):  
Jia Yin ◽  
Wentao Zheng ◽  
Yunsheng Gao ◽  
Chanjuan Jiang ◽  
Hongbo Shi ◽  
...  
Keyword(s):  
Dna Binding ◽  
Homologous Recombination ◽  
Binding Protein ◽  
Dna Binding Protein ◽  
Single Stranded Dna

scholarly journals ATR repression at telomeres by POT1a and POT1b: RPA exclusion and interference by CST

2018 ◽  
Author(s):  
Katja Kratz ◽  
Titia de Lange
Keyword(s):  
Dna Binding ◽  
Binding Protein ◽  
Dna Binding Protein ◽  
Binding Domain ◽  
Telomeric Dna ◽  
Ssdna Binding ◽  
Shelterin Complex ◽  
G4 Dna ◽  
Primase Complex

ABSTRACTTelomeres carry a constitutive 3’ overhang that can bind RPA and activate ATR signaling. POT1a, a single-stranded (ss) DNA binding protein in mouse shelterin, has been proposed to repress ATR signaling by preventing RPA binding. Repression of ATR at telomeres requires the TPP1/TIN2 mediated tethering of POT1a to the the rest of the shelterin complex situated on the ds telomeric DNA. The simplest version of the tethered exclusion model for ATR repression suggests that the only critical features of POT1a are its connection to shelterin and its binding to ss telomeric DNA binding. In agreement with the model, we show that a shelterin-tethered RPA70 mutant, lacking the ATR recruitment domain, is effective in repressing ATR signaling at telomeres. However, arguing against the simple tethered exclusion model, the nearly identical POT1b subunit of shelterin is much less proficient in ATR repression than POT1a. We now show that POT1b has the intrinsic ability to fully repress ATR but is prevented from doing so when bound to the CST/Polα/primase complex. The data establish that shelterin represses ATR with a tethered ssDNA-binding domain that excludes RPA from the 3’ overhang and suggest that ATR repression does not require the interaction of POT1 with the 3’ end or G4 DNA.

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