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Tousled kinase TLK1B counteracts the effect of Asf1 in inhibition of histone H3-H4 tetramer formation.

De Benedetti A - BMC Res Notes (2009)

Bottom Line: We found that TLK1B, by virtue of its binding to Asf1, can restore formation of H3-H4 tetramers that is sterically prevented by adding Asf1.We suggest that TLK1B binds to Asf1 in a manner that interferes with its binding to the H3-H4 dimer, thereby allowing for H3-H4 tetramerization.A description of the function of TLK1 and Asf1 in chromatin remodeling is presented.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biochemistry and Molecular Biology and the Feist-Weiller Cancer Center, Louisiana State University Health Sciences Center, Shreveport, LA 71130, USA. adeben@lsuhsc.edu

ABSTRACT

Background: The Tousled-like kinases (TLKs) function in processes of chromatin assembly, including replication, transcription, repair, and chromosome segregation. TLK1 interacts specifically with the chromatin assembly factor Asf1, a histone H3-H4 chaperone, and with Rad9, a protein involved in DNA repair. Asf1 binds to the H3-H4 dimer at the same interface that is used for formation of the core tetramer, and hence Asf1 is implicated in disruption of the tetramer during transcription, although Asf1 also has a function in chromatin assembly during replication and repair.

Findings: We have used protein crosslinking with purified components to probe the interaction between H3, H4, Asf1, and TLK1B. We found that TLK1B, by virtue of its binding to Asf1, can restore formation of H3-H4 tetramers that is sterically prevented by adding Asf1.

Conclusion: We suggest that TLK1B binds to Asf1 in a manner that interferes with its binding to the H3-H4 dimer, thereby allowing for H3-H4 tetramerization. A description of the function of TLK1 and Asf1 in chromatin remodeling is presented.

No MeSH data available.


Related in: MedlinePlus

A. Crosslinking of H3–H4. Histones H3 and H4 were incubated for the indicated minutes and then crosslinked with formaldehyde before separation on a 15% SDS/PAGE. The blot was probed separately with anti-H3 and anti-H4. B. Effect of Asf1 and TLK1B on H3–H4 dimer and tetramer formation. Reactions containing the indicated combinations of H3, H4, Asf1, and TLK1B (all in equivalent amount) were crosslinked as described in Methods and immunoblotted for H4 or H3. C. Western blots for Asf1 and TLK1B. The indicated reactions as in panel B were run in duplicate lanes and immunoblotted for Asf1, H3, or TLK1B (the gel was run for a longer time than in panel B to separate the larger proteins). For antibody controls, lane 1 contained only Asf1, and lane 7 contained only TLK1B. The positions of the cross-linked complexes identified by mobility and immunoreactivity are indicated. D. TLK1B and Asf1 bind each other stoichiometrically. Reactions contained 5 μg of GST-TLK1B and varying amounts of Asf1, as indicated. After 10 min at room temperature, the samples were adsorbed on GSH-Sepharose and analyzed for bound and unbound fractions after separation on a 10% SDS/PAGE, which was stained with Coomassie blue. E. Interaction of TLK1B and Asf1 and the effect of ATP. GST-TLK1B and Asf1 (1 μg each) were incubated for 10 min at room temperature with and without 10 or 100 μM ATP, before analysis by GSH-Sepharose pull-down. The 10% SDS/PAGE gel was stained with Coomassie blue. F. MNase digestion of pBluescript assembled into pseudo-nucleosomes. In the left panel, naked supercoiled plasmid was digested with MNase for the indicated time. In the right panel, the plasmid was first incubated with equimolar H3 and H4 in high salt and then step-dialyzed as described in [3], before MNase digestion. The DNA was re-extracted from the reactions with Geneclean and run on a 1.5% agarose/TAE gel. The resulting ~120 bp ladder (a bit shorter than the repetitive 146 bp of nucleosomal DNA) is indicative of formation of a chromatinized template. The positions of the bands of a 100-bp ladder (GenRuler, Fermentas) are indicated.
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Figure 1: A. Crosslinking of H3–H4. Histones H3 and H4 were incubated for the indicated minutes and then crosslinked with formaldehyde before separation on a 15% SDS/PAGE. The blot was probed separately with anti-H3 and anti-H4. B. Effect of Asf1 and TLK1B on H3–H4 dimer and tetramer formation. Reactions containing the indicated combinations of H3, H4, Asf1, and TLK1B (all in equivalent amount) were crosslinked as described in Methods and immunoblotted for H4 or H3. C. Western blots for Asf1 and TLK1B. The indicated reactions as in panel B were run in duplicate lanes and immunoblotted for Asf1, H3, or TLK1B (the gel was run for a longer time than in panel B to separate the larger proteins). For antibody controls, lane 1 contained only Asf1, and lane 7 contained only TLK1B. The positions of the cross-linked complexes identified by mobility and immunoreactivity are indicated. D. TLK1B and Asf1 bind each other stoichiometrically. Reactions contained 5 μg of GST-TLK1B and varying amounts of Asf1, as indicated. After 10 min at room temperature, the samples were adsorbed on GSH-Sepharose and analyzed for bound and unbound fractions after separation on a 10% SDS/PAGE, which was stained with Coomassie blue. E. Interaction of TLK1B and Asf1 and the effect of ATP. GST-TLK1B and Asf1 (1 μg each) were incubated for 10 min at room temperature with and without 10 or 100 μM ATP, before analysis by GSH-Sepharose pull-down. The 10% SDS/PAGE gel was stained with Coomassie blue. F. MNase digestion of pBluescript assembled into pseudo-nucleosomes. In the left panel, naked supercoiled plasmid was digested with MNase for the indicated time. In the right panel, the plasmid was first incubated with equimolar H3 and H4 in high salt and then step-dialyzed as described in [3], before MNase digestion. The DNA was re-extracted from the reactions with Geneclean and run on a 1.5% agarose/TAE gel. The resulting ~120 bp ladder (a bit shorter than the repetitive 146 bp of nucleosomal DNA) is indicative of formation of a chromatinized template. The positions of the bands of a 100-bp ladder (GenRuler, Fermentas) are indicated.

Mentions: To test the effect of Asf1 and TLK1B on formation of H3–H4 dimers and tetramers, conditions were first optimized for the time of assembly and method of crosslinking with formaldehyde. Figure 1A shows the formation of the cross-linked H3–H4 dimer and tetramer during a time course of assembly at room temperature, as described in Methods. The gel was blotted and probed with H3 or H4 antiserum.


Tousled kinase TLK1B counteracts the effect of Asf1 in inhibition of histone H3-H4 tetramer formation.

De Benedetti A - BMC Res Notes (2009)

A. Crosslinking of H3–H4. Histones H3 and H4 were incubated for the indicated minutes and then crosslinked with formaldehyde before separation on a 15% SDS/PAGE. The blot was probed separately with anti-H3 and anti-H4. B. Effect of Asf1 and TLK1B on H3–H4 dimer and tetramer formation. Reactions containing the indicated combinations of H3, H4, Asf1, and TLK1B (all in equivalent amount) were crosslinked as described in Methods and immunoblotted for H4 or H3. C. Western blots for Asf1 and TLK1B. The indicated reactions as in panel B were run in duplicate lanes and immunoblotted for Asf1, H3, or TLK1B (the gel was run for a longer time than in panel B to separate the larger proteins). For antibody controls, lane 1 contained only Asf1, and lane 7 contained only TLK1B. The positions of the cross-linked complexes identified by mobility and immunoreactivity are indicated. D. TLK1B and Asf1 bind each other stoichiometrically. Reactions contained 5 μg of GST-TLK1B and varying amounts of Asf1, as indicated. After 10 min at room temperature, the samples were adsorbed on GSH-Sepharose and analyzed for bound and unbound fractions after separation on a 10% SDS/PAGE, which was stained with Coomassie blue. E. Interaction of TLK1B and Asf1 and the effect of ATP. GST-TLK1B and Asf1 (1 μg each) were incubated for 10 min at room temperature with and without 10 or 100 μM ATP, before analysis by GSH-Sepharose pull-down. The 10% SDS/PAGE gel was stained with Coomassie blue. F. MNase digestion of pBluescript assembled into pseudo-nucleosomes. In the left panel, naked supercoiled plasmid was digested with MNase for the indicated time. In the right panel, the plasmid was first incubated with equimolar H3 and H4 in high salt and then step-dialyzed as described in [3], before MNase digestion. The DNA was re-extracted from the reactions with Geneclean and run on a 1.5% agarose/TAE gel. The resulting ~120 bp ladder (a bit shorter than the repetitive 146 bp of nucleosomal DNA) is indicative of formation of a chromatinized template. The positions of the bands of a 100-bp ladder (GenRuler, Fermentas) are indicated.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Figure 1: A. Crosslinking of H3–H4. Histones H3 and H4 were incubated for the indicated minutes and then crosslinked with formaldehyde before separation on a 15% SDS/PAGE. The blot was probed separately with anti-H3 and anti-H4. B. Effect of Asf1 and TLK1B on H3–H4 dimer and tetramer formation. Reactions containing the indicated combinations of H3, H4, Asf1, and TLK1B (all in equivalent amount) were crosslinked as described in Methods and immunoblotted for H4 or H3. C. Western blots for Asf1 and TLK1B. The indicated reactions as in panel B were run in duplicate lanes and immunoblotted for Asf1, H3, or TLK1B (the gel was run for a longer time than in panel B to separate the larger proteins). For antibody controls, lane 1 contained only Asf1, and lane 7 contained only TLK1B. The positions of the cross-linked complexes identified by mobility and immunoreactivity are indicated. D. TLK1B and Asf1 bind each other stoichiometrically. Reactions contained 5 μg of GST-TLK1B and varying amounts of Asf1, as indicated. After 10 min at room temperature, the samples were adsorbed on GSH-Sepharose and analyzed for bound and unbound fractions after separation on a 10% SDS/PAGE, which was stained with Coomassie blue. E. Interaction of TLK1B and Asf1 and the effect of ATP. GST-TLK1B and Asf1 (1 μg each) were incubated for 10 min at room temperature with and without 10 or 100 μM ATP, before analysis by GSH-Sepharose pull-down. The 10% SDS/PAGE gel was stained with Coomassie blue. F. MNase digestion of pBluescript assembled into pseudo-nucleosomes. In the left panel, naked supercoiled plasmid was digested with MNase for the indicated time. In the right panel, the plasmid was first incubated with equimolar H3 and H4 in high salt and then step-dialyzed as described in [3], before MNase digestion. The DNA was re-extracted from the reactions with Geneclean and run on a 1.5% agarose/TAE gel. The resulting ~120 bp ladder (a bit shorter than the repetitive 146 bp of nucleosomal DNA) is indicative of formation of a chromatinized template. The positions of the bands of a 100-bp ladder (GenRuler, Fermentas) are indicated.
Mentions: To test the effect of Asf1 and TLK1B on formation of H3–H4 dimers and tetramers, conditions were first optimized for the time of assembly and method of crosslinking with formaldehyde. Figure 1A shows the formation of the cross-linked H3–H4 dimer and tetramer during a time course of assembly at room temperature, as described in Methods. The gel was blotted and probed with H3 or H4 antiserum.

Bottom Line: We found that TLK1B, by virtue of its binding to Asf1, can restore formation of H3-H4 tetramers that is sterically prevented by adding Asf1.We suggest that TLK1B binds to Asf1 in a manner that interferes with its binding to the H3-H4 dimer, thereby allowing for H3-H4 tetramerization.A description of the function of TLK1 and Asf1 in chromatin remodeling is presented.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biochemistry and Molecular Biology and the Feist-Weiller Cancer Center, Louisiana State University Health Sciences Center, Shreveport, LA 71130, USA. adeben@lsuhsc.edu

ABSTRACT

Background: The Tousled-like kinases (TLKs) function in processes of chromatin assembly, including replication, transcription, repair, and chromosome segregation. TLK1 interacts specifically with the chromatin assembly factor Asf1, a histone H3-H4 chaperone, and with Rad9, a protein involved in DNA repair. Asf1 binds to the H3-H4 dimer at the same interface that is used for formation of the core tetramer, and hence Asf1 is implicated in disruption of the tetramer during transcription, although Asf1 also has a function in chromatin assembly during replication and repair.

Findings: We have used protein crosslinking with purified components to probe the interaction between H3, H4, Asf1, and TLK1B. We found that TLK1B, by virtue of its binding to Asf1, can restore formation of H3-H4 tetramers that is sterically prevented by adding Asf1.

Conclusion: We suggest that TLK1B binds to Asf1 in a manner that interferes with its binding to the H3-H4 dimer, thereby allowing for H3-H4 tetramerization. A description of the function of TLK1 and Asf1 in chromatin remodeling is presented.

No MeSH data available.


Related in: MedlinePlus