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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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UV melting curves of AT-DNA.The molar ratios of protein:DNA base pairs were at 1∶30 to 1∶5 for Alba1 (a) and at 1∶30 to 1∶2 for Alba2 (b) and the Alba1/Alba2 complex (c).
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pone-0058237-g005: UV melting curves of AT-DNA.The molar ratios of protein:DNA base pairs were at 1∶30 to 1∶5 for Alba1 (a) and at 1∶30 to 1∶2 for Alba2 (b) and the Alba1/Alba2 complex (c).

Mentions: The effects of Alba1 and Alba2 and the equimolar mixture of Alba1/Alba2 on the thermal profiles of these DNAs are shown in Figures 4, 5 and 6. The melting temperature (Tm) of CT-DNA at pH 7.0 (50 mM NaH2PO4) in the absence of the proteins was 83°C, and this increased to 86°C at the molar ratio of 1∶5 of Alba1:CT-DNA base pairs (Table 1). Although only a small thermal stabilisation effect was seen here (ΔTmca. 3°C), a significant condensation effect of Alba2 on CT-DNA was seen at molar ratios of 1∶10 and higher (Figure 4b). The addition of the Alba1 protein to AT-DNA had no significant effects on its thermal stability, although condensation of AT-DNA was seen at molar ratios higher than 1∶5 (Figure 5a). Similarly, the addition of the Alba1 protein to GC-DNA had no significant thermal stabilisation effects on the DNA, as the difference in the Tm at Alba1:GC-DNA molar ratios up to 1∶20 was only 1.5°C (Figure 6a).


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)

UV melting curves of AT-DNA.The molar ratios of protein:DNA base pairs were at 1∶30 to 1∶5 for Alba1 (a) and at 1∶30 to 1∶2 for Alba2 (b) and the Alba1/Alba2 complex (c).
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3585288&req=5

pone-0058237-g005: UV melting curves of AT-DNA.The molar ratios of protein:DNA base pairs were at 1∶30 to 1∶5 for Alba1 (a) and at 1∶30 to 1∶2 for Alba2 (b) and the Alba1/Alba2 complex (c).
Mentions: The effects of Alba1 and Alba2 and the equimolar mixture of Alba1/Alba2 on the thermal profiles of these DNAs are shown in Figures 4, 5 and 6. The melting temperature (Tm) of CT-DNA at pH 7.0 (50 mM NaH2PO4) in the absence of the proteins was 83°C, and this increased to 86°C at the molar ratio of 1∶5 of Alba1:CT-DNA base pairs (Table 1). Although only a small thermal stabilisation effect was seen here (ΔTmca. 3°C), a significant condensation effect of Alba2 on CT-DNA was seen at molar ratios of 1∶10 and higher (Figure 4b). The addition of the Alba1 protein to AT-DNA had no significant effects on its thermal stability, although condensation of AT-DNA was seen at molar ratios higher than 1∶5 (Figure 5a). Similarly, the addition of the Alba1 protein to GC-DNA had no significant thermal stabilisation effects on the DNA, as the difference in the Tm at Alba1:GC-DNA molar ratios up to 1∶20 was only 1.5°C (Figure 6a).

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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