Telomeric double-strand DNA-binding proteins DTN-1 and DTN-2 ensure germline immortality in Caenorhabditis elegans

Telomeres are nucleoprotein complexes at the ends of chromosomes and are indispensable for the protection and lengthening of terminal DNA. Despite the evolutionarily conserved roles of telomeres, the telomeric double-strand DNA (dsDNA)-binding proteins have evolved rapidly. Here, we identified double-strand telomeric DNA-binding proteins (DTN-1 and DTN-2) in Caenorhabditis elegans as non-canonical telomeric dsDNA-binding proteins. DTN-1 and DTN-2 are paralogous proteins that have three putative MYB-like DNA-binding domains and bind to telomeric dsDNA in a sequence-specific manner. DTN-1 and DTN-2 form complexes with the single-strand telomeric DNA-binding proteins POT-1 and POT-2 and constitutively localize to telomeres. The dtn-1 and dtn-2 genes function redundantly, and their simultaneous deletion results in progressive germline mortality, which accompanies telomere hyper-elongation and chromosomal bridges. Our study suggests that DTN-1 and DTN-2 are core shelterin components in C. elegans telomeres that act as negative regulators of telomere length and are essential for germline immortality.

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Mapping and analysis of Caenorhabditis elegans transcription factor sequence specificities

eLife ◽

10.7554/elife.06967 ◽

2015 ◽

Vol 4 ◽

Cited By ~ 41

Author(s):

Kamesh Narasimhan ◽

Samuel A Lambert ◽

Ally WH Yang ◽

Jeremy Riddell ◽

Sanie Mnaimneh ◽

...

Keyword(s):

Caenorhabditis Elegans ◽

Dna Binding ◽

Regulatory Elements ◽

Nuclear Hormone Receptor ◽

Binding Motifs ◽

T Box ◽

C Elegans ◽

Dna Binding Domains ◽

Binding Domains ◽

Protein Binding Microarray

Caenorhabditis elegans is a powerful model for studying gene regulation, as it has a compact genome and a wealth of genomic tools. However, identification of regulatory elements has been limited, as DNA-binding motifs are known for only 71 of the estimated 763 sequence-specific transcription factors (TFs). To address this problem, we performed protein binding microarray experiments on representatives of canonical TF families in C. elegans, obtaining motifs for 129 TFs. Additionally, we predict motifs for many TFs that have DNA-binding domains similar to those already characterized, increasing coverage of binding specificities to 292 C. elegans TFs (∼40%). These data highlight the diversification of binding motifs for the nuclear hormone receptor and C2H2 zinc finger families and reveal unexpected diversity of motifs for T-box and DM families. Motif enrichment in promoters of functionally related genes is consistent with known biology and also identifies putative regulatory roles for unstudied TFs.

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Rapid isolation fo specific DNA-binding proteins and their DNA-binding domains

Nucleic Acids Research ◽

10.1093/nar/20.15.4103 ◽

1992 ◽

Vol 20 (15) ◽

pp. 4103-4104 ◽

Cited By ~ 1

Author(s):

Urszula Wichser ◽

Christine Brack

Keyword(s):

Dna Binding ◽

Binding Proteins ◽

Dna Binding Proteins ◽

Rapid Isolation ◽

Dna Binding Domains ◽

Binding Domains

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The bldC Developmental Locus of Streptomyces coelicolor Encodes a Member of a Family of Small DNA-Binding Proteins Related to the DNA-Binding Domains of the MerR Family

Journal of Bacteriology ◽

10.1128/jb.187.2.716-728.2005 ◽

2005 ◽

Vol 187 (2) ◽

pp. 716-728 ◽

Cited By ~ 24

Author(s):

Alison C. Hunt ◽

Luis Servín-González ◽

Gabriella H. Kelemen ◽

Mark J. Buttner

Keyword(s):

Dna Binding ◽

Binding Proteins ◽

Antibiotic Production ◽

Streptomyces Coelicolor ◽

Aerial Mycelium ◽

Dna Binding Proteins ◽

S1 Nuclease ◽

Dna Binding Domains ◽

Binding Domains ◽

Wide Range

ABSTRACT The bldC locus, required for formation of aerial hyphae in Streptomyces coelicolor, was localized by map-based cloning to the overlap between cosmids D17 and D25 of a minimal ordered library. Subcloning and sequencing showed that bldC encodes a member of a previously unrecognized family of small (58- to 78-residue) DNA-binding proteins, related to the DNA-binding domains of the MerR family of transcriptional activators. BldC family members are found in a wide range of gram-positive and gram-negative bacteria. Constructed ΔbldC mutants were defective in differentiation and antibiotic production. They failed to form an aerial mycelium on minimal medium and showed severe delays in aerial mycelium formation on rich medium. In addition, they failed to produce the polyketide antibiotic actinorhodin, and bldC was shown to be required for normal and sustained transcription of the pathway-specific activator gene actII-orf4. Although ΔbldC mutants produced the tripyrrole antibiotic undecylprodigiosin, transcripts of the pathway-specific activator gene (redD) were reduced to almost undetectable levels after 48 h in the bldC mutant, in contrast to the bldC + parent strain in which redD transcription continued during aerial mycelium formation and sporulation. This suggests that bldC may be required for maintenance of redD transcription during differentiation. bldC is expressed from a single promoter. S1 nuclease protection assays and immunoblotting showed that bldC is constitutively expressed and that transcription of bldC does not depend on any of the other known bld genes. The bldC18 mutation that originally defined the locus causes a Y49C substitution that results in instability of the protein.

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Characterization of the dead ringer gene identifies a novel, highly conserved family of sequence-specific DNA-binding proteins.

Molecular and Cellular Biology ◽

10.1128/mcb.16.3.792 ◽

1996 ◽

Vol 16 (3) ◽

pp. 792-799 ◽

Cited By ~ 96

Author(s):

S L Gregory ◽

R D Kortschak ◽

B Kalionis ◽

R Saint

Keyword(s):

Dna Binding ◽

Binding Proteins ◽

Dna Binding Proteins ◽

Binding Domain ◽

Dna Binding Domain ◽

Dna Binding Domains ◽

Binding Domains ◽

The Dead

We reported the identification of a new family of DNA-binding proteins from our characterization of the dead ringer (dri) gene of Drosophila melanogaster. We show that dri encodes a nuclear protein that contains a sequence-specific DNA-binding domain that bears no similarity to known DNA-binding domains. A number of proteins were found to contain sequences homologous to this domain. Other proteins containing the conserved motif include yeast SWI1, two human retinoblastoma binding proteins, and other mammalian regulatory proteins. A mouse B-cell-specific regulator exhibits 75% identity with DRI over the 137-amino-acid DNA-binding domains of these proteins, indicating a high degree of conservation of this domain. Gel retardation and optimal binding site screens revealed that the in vitro sequence specificity of DRI is strikingly similar to that of many homeodomain proteins, although the sequence and predicted secondary structure do not resemble a homeodomain. The early general expression of dri and the similarity of DRI and homeodomain in vitro DNA-binding specificity compound the problem of understanding the in vivo specificity of action of these proteins. Maternally derived dri product is found throughout the embryo until germ band extension, when dri is expressed in a developmentally regulated set of tissues, including salivary gland ducts, parts of the gut, and a subset of neural cells. The discovery of this new, conserved DNA-binding domain offers an explanation for the regulatory activity of several important members of this class and predicts significant regulatory roles for the others.

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Heteronuclear Strategies for the Assignment of Larger protein/DNA complexes: Application to the 37 kDa trp Represser-Operator Complex

Biological NMR Spectroscopy ◽

10.1093/oso/9780195094688.003.0012 ◽

1997 ◽

Author(s):

M.J. Revington ◽

W. Lee

Keyword(s):

Dna Binding ◽

Binding Proteins ◽

Dna Binding Proteins ◽

Binding Domain ◽

Dna Binding Domain ◽

Nmr Studies ◽

Dna Complexes ◽

Dna Binding Domains ◽

Binding Domains

The sequence-specific DNA binding function of many proteins is recognized as one of the central mechanisms of regulating transcription and DNA replication and repair. The ability of these proteins to select a short (usually 10 to 20 basepair) sequence out of the entire genome with which to form a stable complex is a prime example of molecular recognition. Atomic resolution structural studies using NMR and X-ray crystallography have emerged as essential techniques in understanding the basis of specificity and stability in these systems. While NMR studies of small DNA-binding domains of proteins have become almost routine (see Kaptein, 1993 for a review) relatively few NMR studies of protein-DNA complexes have been reported. These include the lac repressor headpiece complex (Chuprina et al., 1993). the Antennapedia homeodomain complex (Billetere et al., 1993), the GATA-1 complex (Omichinski et al., 1993). and the Myb DNA binding domain complex (Ogata et al., 1993); all of these complexes are smaller than 20 kDa. In most cases, size limitations have meant that only the DNA binding domain of the protein in complex with a single binding element have been studied. In vivo, however, most DNA binding proteins are much larger than these domains and often function as oligomers. The decrease in quality and increase in complexity of spectra as the molecular weight of the sample increases, limits the number of systems amenable to study using NMR and influences the decision to focus on single domains of multidomain proteins. However, since many DNA-binding proteins are regulated by the binding of ligands, other proteins or phosphorylation, often at sites distal from the DNA-binding domain, it is preferable to study as much of the intact protein as possible in order to characterize allosteric and regulatory mechanisms (Pabo and Sauer, 1992). E. coli trp repressor is a 25 kDa homodimer that regulates operons involved in tryptophan biosynthesis. The dimer is one of the smallest intact proteins that binds sequence specifically to DNA and whose affinity is modulated by an effector (L-tryptophan).

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DNA binding proteins: outline of functional classification

BioMolecular Concepts ◽

10.1515/bmc.2011.023 ◽

2011 ◽

Vol 2 (4) ◽

pp. 293-303 ◽

Cited By ~ 2

Author(s):

Zhiming Zheng ◽

Ya Wang

Keyword(s):

Dna Repair ◽

Dna Replication ◽

Dna Binding ◽

Dna Sequences ◽

Binding Proteins ◽

Excision Repair ◽

Dna Structure ◽

Dna Binding Proteins ◽

Dna Binding Domains ◽

Binding Domains

AbstractDNA-binding proteins composed of DNA-binding domains directly affect genomic functions, mainly by performing transcription, DNA replication or DNA repair. Here, we briefly describe the DNA-binding proteins according to these three major functions. Transcription factors that usually bind to specific sequences of DNA could be classified based on their sequence similarity and the structure of the DNA-binding domains, such as basic, zinc-coordinating, helix-turn-helix domains, etc. Most DNA replication factors do not need a specific sequence of DNA, but instead mainly depend on a DNA structure, with the exception of the origin recognition complex in yeast or Escherichia coli that recognizes the DNA sequences at particular origins. DNA replication includes initiation and elongation. The major DNA-binding proteins involved in these two steps are briefly described. DNA repair proteins bound to DNA depend on the damaged DNA structure. They are classified to base excision repair, DNA mismatch repair, nucleotide excision repair, homologous recombination repair and non-homologous end joining. The major DNA-binding proteins involved in these pathways are briefly described. Histone and high mobility group are two examples of DNA-binding proteins that do not belong to the three categories above and are briefly described. Finally, we warn that the non-specific binding proteins might have an affinity to some non-specific medium materials such as protein A or G beads that are commonly used for immune precipitation, which can easily generate false positive signals while detecting protein-protein interaction; therefore, the results need to be carefully analyzed using positive/negative controls.

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Cdc13 N-Terminal Dimerization, DNA Binding, and Telomere Length Regulation

Molecular and Cellular Biology ◽

10.1128/mcb.00515-10 ◽

2010 ◽

Vol 30 (22) ◽

pp. 5325-5334 ◽

Cited By ~ 23

Author(s):

Meghan T. Mitchell ◽

Jasmine S. Smith ◽

Mark Mason ◽

Sandy Harper ◽

David W. Speicher ◽

...

Keyword(s):

Dna Binding ◽

Telomere Length ◽

Functional Characterization ◽

Point Mutations ◽

Telomeric Dna ◽

Dna Binding Domains ◽

Binding Domains ◽

Length Regulation ◽

Telomere Length Regulation

ABSTRACT The essential yeast protein Cdc13 facilitates chromosome end replication by recruiting telomerase to telomeres, and together with its interacting partners Stn1 and Ten1, it protects chromosome ends from nucleolytic attack, thus contributing to genome integrity. Although Cdc13 has been studied extensively, the precise role of its N-terminal domain (Cdc13N) in telomere length regulation remains unclear. Here we present a structural, biochemical, and functional characterization of Cdc13N. The structure reveals that this domain comprises an oligonucleotide/oligosaccharide binding (OB) fold and is involved in Cdc13 dimerization. Biochemical data show that Cdc13N weakly binds long, single-stranded, telomeric DNA in a fashion that is directly dependent on domain oligomerization. When introduced into full-length Cdc13 in vivo, point mutations that prevented Cdc13N dimerization or DNA binding caused telomere shortening or lengthening, respectively. The multiple DNA binding domains and dimeric nature of Cdc13 offer unique insights into how it coordinates the recruitment and regulation of telomerase access to the telomeres.

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