What the papers say: Telomeric DNA binding proteins

Lin, J. G.

doi:10.1002/bies.950150809

Cited by 4 publications

(4 citation statements)

References 25 publications

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“…Specific nuclear TBPs from a variety of organisms were recently identified (33,48). The first isolated and best characterized is TBP from Oxytricha nova which is a heterodimer of two different polypeptides ␣ and ␤ (12, 13).…”

Section: Mitochondria Of C Parapsilosis Contain a Mitochondrialmentioning

confidence: 99%

“…For nuclear genomes, specific telomere-binding proteins (TBPs) 1 have been identified in protozoa (11)(12)(13)(14)(15)(16), slime molds (17,18), yeasts (19 -26), algae (27), plants (28), and vertebrates (29 -32). These proteins presumably protect the telomere DNA from nucleolytic degradation, mediate telomeretelomere and telomere-nuclear matrix interactions, promote the formation of a typical telomeric structure, and regulate the accessibility of telomeres to the replication machinery (33). They may also participate in the events associated with the cell cycle (34) and cellular senescence (35).…”

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Identification of a Putative Mitochondrial Telomere-binding Protein of the Yeast Candida parapsilosis

Tomáška¹,

Nosek

Fukuhara

1997

Journal of Biological Chemistry

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Terminal segments (telomeres) of linear mitochondrial DNA (mtDNA) molecules of the yeast Candida parapsilosis consist of large sequence units repeated in tandem. The extreme ends of mtDNA terminate with a 5 single-stranded overhang of about 110 nucleotides. We identified and purified a mitochondrial telomere-binding protein (mtTBP) that specifically recognizes a synthetic oligonucleotide derived from the extreme end of this linear mtDNA. MtTBP is highly resistant to protease and heat treatments, and it protects the telomeric probe from degradation by various DNA-modifying enzymes. Resistance of the complex to bacterial alkaline phosphatase suggests that mtTBP binds the very end of the molecule. We purified mtTBP to near homogeneity using DNA affinity chromatography based on the telomeric oligonucleotide covalently bound to Sepharose. Sodium dodecyl sulfate-polyacrylamide gel electrophoretic analysis of the purified fractions revealed the presence of a protein with an apparent molecular mass of ϳ15 kDa. UV cross-linking and gel filtration chromatography experiments suggested that native mtTBP is probably a homo-oligomer. MtTBP of C. parapsilosis is the first identified protein that specifically binds to telomeres of linear mitochondrial DNA.Although circularity is accepted as the most common form of mitochondrial DNA (mtDNA), there are numerous examples of organisms with linear mtDNA, raising questions about their evolutionary origin and mode of replication (1). Mitochondrial genomes of many yeast species are represented by linear DNA molecules with defined terminal structures (2-5). Two different types of yeast linear mtDNA have been described. Type 1 (Pichia pijperi, Pichia jadinii, Williopsis mrakii) possesses inverted terminal repeats with a covalently closed singlestranded hairpin at each ends (6). In contrast, terminal structures of type 2 linear mtDNA (Candida parapsilosis, Candida salmanticensis, Pichia philodendra) have inverted terminal repeats consisting of units repeated in tandem. The variable number of repeat units generates a population of mtDNA molecules of heterogeneous size. The largest fraction of mtDNA molecules of C. parapsilosis is represented by the shortest molecules, which contain only one incomplete tandem repeat unit. Regardless of the number of repetitions, both ends of the mtDNA molecule terminate at a unique position in the last repeat unit sequence thus leaving an open structure with a 5Ј single-stranded extension of about 110 nucleotides (7). This is in contrast to typical nuclear telomeres of most eukaryotes consisting of simple arrays of tandem G-rich repeats that run 5Ј to 3Ј at the chromosome ends and protrude as 3Ј overhangs (8). The structure of the mitochondrial telomeres of C. parapsilosis is more reminiscent of those of Tetrahymena mtDNA, although the telomeric tandem repeat unit of the latter is considerably shorter (9, 10). The role of terminal structures in the replication and maintenance of C. parapsilosis mtDNA is not known. Their unique organization raised many intri...

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Section: Mitochondria Of C Parapsilosis Contain a Mitochondrialmentioning

confidence: 99%

mentioning

confidence: 99%

Identification of a Putative Mitochondrial Telomere-binding Protein of the Yeast Candida parapsilosis

Tomáška¹,

Nosek

Fukuhara

1997

Journal of Biological Chemistry

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“…Telomere binding proteins have been identified and characterized in several organisms (15). Such telomere binding proteins could mediate any of the functions attributed to telomeres themselves.…”

Section: Introductionmentioning

confidence: 99%

Isolation and characterization of twoSaccharomyces cerevisiaegenes that encode proteins that bind to (TG_1–3)_nsingle strand telomeric DNAin vitro

Lin

Zakian

1994

Nucl Acids Res

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By screening lambda gt11 libraries with a radiolabeled (TG1-3)n oligonucleotide, two Saccharomyces cerevisiae genes were identified that encode polypeptides that recognize the single-stranded telomeric repeat sequence (TG1-3)n. The first gene, NSR1, a previously identified gene, encodes a protein involved in ribosomal RNA maturation and possibly in transport of proteins into the nucleus. The second gene, GBP2 (G-strand Binding Protein), is an anonymous open reading frame from chromosome III. These two genes contain RNA recognition motifs (RRMs) that are found in proteins that interact with RNA. Both Nsr1p and Gbp2p bind specifically to yeast single strand (TG1-3)n DNA in vitro. To test whether these two proteins associate with telomeres in vivo, strains were constructed in which one or both of these genes were either disrupted or overexpressed. None of these alterations affected telomere length or telomere position effect. The potential role of these two (TG1-3)n binding proteins is discussed.

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“…Protein factors that bind to the single-stranded telomeric DNA have been identified in several organisms (11)(12)(13)(14)(15)(16)(17)(18)(19). Among these protein factors, Oxytricha telomere-binding protein has been well characterized.…”

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Specific Binding of Single-stranded Telomeric DNA by Cdc13p ofSaccharomyces cerevisiae

Lin¹,

Hsu²,

Shih³

et al. 2001

Journal of Biological Chemistry

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Cdc13p is a single strand telomere-binding protein of Saccharomyces cerevisiae; its telomere-binding region is within amino acids 451-693, Cdc13(451-693)p. In this study, we used purified Cdc13p and Cdc13(451-693)p to characterize their telomere binding activity. We found that the binding specificity of single-stranded TG 1-3 DNA by these two proteins is similar. However, the affinity of Cdc13(451-693)p to DNA was slightly lower than that of Cdc13p. The binding of telomeric DNA by these two proteins was disrupted at NaCl concentrations higher than 0.3 M, indicating that electrostatic interaction contributed significantly to the binding process. Because both proteins bound to strand TG 1-3 DNA positioned at the 3 end, the 5 end, or in the middle of the oligonucleotide substrates, our results indicated that the location of TG 1-3 in single-stranded DNA does not appear to be important for Cdc13p binding. Moreover, using DNase I footprint analysis, the structure of the telomeric DNA complexes of Cdc13p and Cdc13(451-693)p was analyzed. The DNase I footprints of these two proteins to three different telomeric DNA substrates were virtually identical, indicating that the telomere contact region of Cdc13p is within Cdc13(451-693)p. Together, the binding properties of Cdc13p and its binding domain support the theory that the specific binding of Cdc13p to telomeres is an important feature of telomeres that regulate telomerase access and/or differentiate natural telomeres from broken ends.

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What the papers say: Telomeric DNA binding proteins

Cited by 4 publications

References 25 publications

Identification of a Putative Mitochondrial Telomere-binding Protein of the Yeast Candida parapsilosis

Identification of a Putative Mitochondrial Telomere-binding Protein of the Yeast Candida parapsilosis

Isolation and characterization of twoSaccharomyces cerevisiaegenes that encode proteins that bind to (TG_1–3)_nsingle strand telomeric DNAin vitro

Specific Binding of Single-stranded Telomeric DNA by Cdc13p ofSaccharomyces cerevisiae

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What the papers say: Telomeric DNA binding proteins

Cited by 4 publications

References 25 publications

Identification of a Putative Mitochondrial Telomere-binding Protein of the Yeast Candida parapsilosis

Identification of a Putative Mitochondrial Telomere-binding Protein of the Yeast Candida parapsilosis

Isolation and characterization of twoSaccharomyces cerevisiaegenes that encode proteins that bind to (TG1–3)nsingle strand telomeric DNAin vitro

Specific Binding of Single-stranded Telomeric DNA by Cdc13p ofSaccharomyces cerevisiae

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Isolation and characterization of twoSaccharomyces cerevisiaegenes that encode proteins that bind to (TG_1–3)_nsingle strand telomeric DNAin vitro