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Three new structures of left-handed RADA helical filaments: structural flexibility of N-terminal domain is critical for recombinase activity.

Chang YW, Ko TP, Lee CD, Chang YC, Lin KA, Chang CS, Wang AH, Wang TF - PLoS ONE (2009)

Bottom Line: We recently reported a structure of RadA left-handed helical filament, and here present three new structures of RadA left-handed helical filaments.Mutant analysis further confirms that structural flexibility of NTD is essential for RadA's recombinase activity.These results support our previous hypothesis that ATP-dependent axial rotation of RadA nucleoprotein helical filament promotes homologous recombination.

View Article: PubMed Central - PubMed

Affiliation: Institute of Biochemical Science, National Taiwan University, Taipei, Taiwan.

ABSTRACT
RecA family proteins, including bacterial RecA, archaeal RadA, and eukaryotic Dmc1 and Rad51, mediate homologous recombination, a reaction essential for maintaining genome integrity. In the presence of ATP, these proteins bind a single-strand DNA to form a right-handed nucleoprotein filament, which catalyzes pairing and strand exchange with a homologous double-stranded DNA (dsDNA), by as-yet unknown mechanisms. We recently reported a structure of RadA left-handed helical filament, and here present three new structures of RadA left-handed helical filaments. Comparative structural analysis between different RadA/Rad51 helical filaments reveals that the N-terminal domain (NTD) of RadA/Rad51, implicated in dsDNA binding, is highly flexible. We identify a hinge region between NTD and polymerization motif as responsible for rigid body movement of NTD. Mutant analysis further confirms that structural flexibility of NTD is essential for RadA's recombinase activity. These results support our previous hypothesis that ATP-dependent axial rotation of RadA nucleoprotein helical filament promotes homologous recombination.

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Related in: MedlinePlus

Top views of two left-handed RadA helical filaments.The ssDNA binding L1 and L2 motifs are highlighted in hotpink and green, respectively. The dsDNA binding region or N-terminal domain (NTD) are highlighted in blue.
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pone-0004890-g002: Top views of two left-handed RadA helical filaments.The ssDNA binding L1 and L2 motifs are highlighted in hotpink and green, respectively. The dsDNA binding region or N-terminal domain (NTD) are highlighted in blue.

Mentions: A unique property of these left-handed helical filaments, as compared to other known structures of RecA family proteins [22], [23], is that their DNA binding motifs (i.e., L1, L2 and NTD) are all located at the outermost surface of helical filaments. Moreover, the NTDs are separated a long way from L1 and L2 motifs (Figure 2). We found that the locations of the L1 and L2 motifs in the four left-handed helical filaments are relatively conserved, but in contrast, the NTD locations are quite different. For example, the two neighboring NTDs in the 2ZUB helical filament are located at 180° to each other. Subsequently, in each helical turn, two NTDs face in one direction, and the other two face in the opposite direction (Figure 2A). By contrast, in the 2DFL, 2ZUC and 2ZUD helical filaments, each NTD was arrayed perpendicularly from the two neighboring NTDs. As a result, the four NTDs in a helical turn each face in a different direction (Figure 2B).


Three new structures of left-handed RADA helical filaments: structural flexibility of N-terminal domain is critical for recombinase activity.

Chang YW, Ko TP, Lee CD, Chang YC, Lin KA, Chang CS, Wang AH, Wang TF - PLoS ONE (2009)

Top views of two left-handed RadA helical filaments.The ssDNA binding L1 and L2 motifs are highlighted in hotpink and green, respectively. The dsDNA binding region or N-terminal domain (NTD) are highlighted in blue.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2654063&req=5

pone-0004890-g002: Top views of two left-handed RadA helical filaments.The ssDNA binding L1 and L2 motifs are highlighted in hotpink and green, respectively. The dsDNA binding region or N-terminal domain (NTD) are highlighted in blue.
Mentions: A unique property of these left-handed helical filaments, as compared to other known structures of RecA family proteins [22], [23], is that their DNA binding motifs (i.e., L1, L2 and NTD) are all located at the outermost surface of helical filaments. Moreover, the NTDs are separated a long way from L1 and L2 motifs (Figure 2). We found that the locations of the L1 and L2 motifs in the four left-handed helical filaments are relatively conserved, but in contrast, the NTD locations are quite different. For example, the two neighboring NTDs in the 2ZUB helical filament are located at 180° to each other. Subsequently, in each helical turn, two NTDs face in one direction, and the other two face in the opposite direction (Figure 2A). By contrast, in the 2DFL, 2ZUC and 2ZUD helical filaments, each NTD was arrayed perpendicularly from the two neighboring NTDs. As a result, the four NTDs in a helical turn each face in a different direction (Figure 2B).

Bottom Line: We recently reported a structure of RadA left-handed helical filament, and here present three new structures of RadA left-handed helical filaments.Mutant analysis further confirms that structural flexibility of NTD is essential for RadA's recombinase activity.These results support our previous hypothesis that ATP-dependent axial rotation of RadA nucleoprotein helical filament promotes homologous recombination.

View Article: PubMed Central - PubMed

Affiliation: Institute of Biochemical Science, National Taiwan University, Taipei, Taiwan.

ABSTRACT
RecA family proteins, including bacterial RecA, archaeal RadA, and eukaryotic Dmc1 and Rad51, mediate homologous recombination, a reaction essential for maintaining genome integrity. In the presence of ATP, these proteins bind a single-strand DNA to form a right-handed nucleoprotein filament, which catalyzes pairing and strand exchange with a homologous double-stranded DNA (dsDNA), by as-yet unknown mechanisms. We recently reported a structure of RadA left-handed helical filament, and here present three new structures of RadA left-handed helical filaments. Comparative structural analysis between different RadA/Rad51 helical filaments reveals that the N-terminal domain (NTD) of RadA/Rad51, implicated in dsDNA binding, is highly flexible. We identify a hinge region between NTD and polymerization motif as responsible for rigid body movement of NTD. Mutant analysis further confirms that structural flexibility of NTD is essential for RadA's recombinase activity. These results support our previous hypothesis that ATP-dependent axial rotation of RadA nucleoprotein helical filament promotes homologous recombination.

Show MeSH
Related in: MedlinePlus