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Interactions of archaeal chromatin proteins Alba1 and Alba2 with nucleic acids.

Črnigoj M, Podlesek Z, Zorko M, Jerala R, Anderluh G, Ulrih NP - PLoS ONE (2013)

Bottom Line: Alba2 and equimolar mixtures of Alba1/Alba2 have greater effects on the thermal stability of poly(dA-dT).poly(dA-dT).The secondary structures of the Alba proteins are not significantly influenced by DNA binding, even at high temperatures.Based on these data, we conclude that Alba1, Alba2, and equimolar mixtures of Alba1/Alba2 show different properties in their binding to various DNAs.

View Article: PubMed Central - PubMed

Affiliation: Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia.

ABSTRACT

Background: Architectural proteins have important roles in compacting and organising chromosomal DNA. There are two potential histone counterpart peptide sequences (Alba1 and Alba2) in the Aeropyrum pernix genome (APE1832.1 and APE1823).

Methodology/principal findings: THESE TWO PEPTIDES WERE EXPRESSED AND THEIR INTERACTIONS WITH VARIOUS DNAS WERE STUDIED USING A COMBINATION OF VARIOUS EXPERIMENTAL TECHNIQUES: surface plasmon resonance, UV spectrophotometry, circular dichroism-spectropolarimetry, gel-shift assays, and isothermal titration calorimetry.

Conclusions/significance: Our data indicate that there are significant differences in the properties of the Alba1 and Alba2 proteins. Both of these Alba proteins can thermally stabilise DNA polynucleotides, as seen from UV melting curves. Alba2 and equimolar mixtures of Alba1/Alba2 have greater effects on the thermal stability of poly(dA-dT).poly(dA-dT). Surface plasmon resonance sensorgrams for binding of Alba1, Alba2, and equimolar mixtures of Alba1/Alba2 to DNA oligonucleotides show different binding patterns. Circular dichroism indicates that Alba2 has a less-ordered secondary structure than Alba1. The secondary structures of the Alba proteins are not significantly influenced by DNA binding, even at high temperatures. Based on these data, we conclude that Alba1, Alba2, and equimolar mixtures of Alba1/Alba2 show different properties in their binding to various DNAs.

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Isothermal titration calorimetry profiles of Alba1 binding to various DNA.A-DNA (a), and B-DNA (b) and CT-DNA (c), at 25°C in 50 mM NaH2PO4, pH 7.0.
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pone-0058237-g010: Isothermal titration calorimetry profiles of Alba1 binding to various DNA.A-DNA (a), and B-DNA (b) and CT-DNA (c), at 25°C in 50 mM NaH2PO4, pH 7.0.

Mentions: The thermodynamic parameters of Alba1 binding to DNA were determined by ITC (Figure 10). The thermodynamic parameters obtained are given in Table 2, and include: binding stoichiometry (n); binding constant (Kbin); ΔHbin; and TΔSbin. Detailed inspection of the thermodynamic data listed in Table 2 reveals that the binding constant, Kbin, is the highest for CT-DNA, following by the A-DNA and the B-DNA. The binding of Alba1 to A-DNA has an enthalpically favourable ΔHbin, while entropically, the most favourable is the binding of Alba1 to CT-DNA. We could not measure the binding of Alba2 to these DNA oligonucleotides due to the condensation/precipitation, as the concentrations of the Alba proteins were higher for ITC than for the other methods studied here, due to the sensitivity limitations of the method.


Interactions of archaeal chromatin proteins Alba1 and Alba2 with nucleic acids.

Črnigoj M, Podlesek Z, Zorko M, Jerala R, Anderluh G, Ulrih NP - PLoS ONE (2013)

Isothermal titration calorimetry profiles of Alba1 binding to various DNA.A-DNA (a), and B-DNA (b) and CT-DNA (c), at 25°C in 50 mM NaH2PO4, pH 7.0.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3585288&req=5

pone-0058237-g010: Isothermal titration calorimetry profiles of Alba1 binding to various DNA.A-DNA (a), and B-DNA (b) and CT-DNA (c), at 25°C in 50 mM NaH2PO4, pH 7.0.
Mentions: The thermodynamic parameters of Alba1 binding to DNA were determined by ITC (Figure 10). The thermodynamic parameters obtained are given in Table 2, and include: binding stoichiometry (n); binding constant (Kbin); ΔHbin; and TΔSbin. Detailed inspection of the thermodynamic data listed in Table 2 reveals that the binding constant, Kbin, is the highest for CT-DNA, following by the A-DNA and the B-DNA. The binding of Alba1 to A-DNA has an enthalpically favourable ΔHbin, while entropically, the most favourable is the binding of Alba1 to CT-DNA. We could not measure the binding of Alba2 to these DNA oligonucleotides due to the condensation/precipitation, as the concentrations of the Alba proteins were higher for ITC than for the other methods studied here, due to the sensitivity limitations of the method.

Bottom Line: Alba2 and equimolar mixtures of Alba1/Alba2 have greater effects on the thermal stability of poly(dA-dT).poly(dA-dT).The secondary structures of the Alba proteins are not significantly influenced by DNA binding, even at high temperatures.Based on these data, we conclude that Alba1, Alba2, and equimolar mixtures of Alba1/Alba2 show different properties in their binding to various DNAs.

View Article: PubMed Central - PubMed

Affiliation: Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia.

ABSTRACT

Background: Architectural proteins have important roles in compacting and organising chromosomal DNA. There are two potential histone counterpart peptide sequences (Alba1 and Alba2) in the Aeropyrum pernix genome (APE1832.1 and APE1823).

Methodology/principal findings: THESE TWO PEPTIDES WERE EXPRESSED AND THEIR INTERACTIONS WITH VARIOUS DNAS WERE STUDIED USING A COMBINATION OF VARIOUS EXPERIMENTAL TECHNIQUES: surface plasmon resonance, UV spectrophotometry, circular dichroism-spectropolarimetry, gel-shift assays, and isothermal titration calorimetry.

Conclusions/significance: Our data indicate that there are significant differences in the properties of the Alba1 and Alba2 proteins. Both of these Alba proteins can thermally stabilise DNA polynucleotides, as seen from UV melting curves. Alba2 and equimolar mixtures of Alba1/Alba2 have greater effects on the thermal stability of poly(dA-dT).poly(dA-dT). Surface plasmon resonance sensorgrams for binding of Alba1, Alba2, and equimolar mixtures of Alba1/Alba2 to DNA oligonucleotides show different binding patterns. Circular dichroism indicates that Alba2 has a less-ordered secondary structure than Alba1. The secondary structures of the Alba proteins are not significantly influenced by DNA binding, even at high temperatures. Based on these data, we conclude that Alba1, Alba2, and equimolar mixtures of Alba1/Alba2 show different properties in their binding to various DNAs.

Show MeSH