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DNA replication: archaeal oriGINS.

Bell SD - BMC Biol. (2011)

Bottom Line: GINS is an essential eukaryotic DNA replication factor that is found in a simplified form in Archaea.A new study in this issue of BMC Biology reveals the first structure of the archaeal GINS complex.The structure reveals the anticipated similarity to the previously determined eukaryotic complex but also has some intriguing differences in the relative disposition of subunit domains.

View Article: PubMed Central - HTML - PubMed

Affiliation: Sir William Dunn School of Pathology, Oxford OX1 3RE, UK. Stephen.bell@path.ox.ac.uk

ABSTRACT
GINS is an essential eukaryotic DNA replication factor that is found in a simplified form in Archaea. A new study in this issue of BMC Biology reveals the first structure of the archaeal GINS complex. The structure reveals the anticipated similarity to the previously determined eukaryotic complex but also has some intriguing differences in the relative disposition of subunit domains.

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Related in: MedlinePlus

Model for the initial assembly of the archaeal replisome based on recent advances in the eukaryotic DNA replication field (see [8,9]). (a) A double hexamer of MCM (gray) is loaded on double-stranded DNA at an archaeal replication origin. (b) The two individual hexamers are held together, so that, instead of moving apart, they will pump DNA into the central cavity of the assembly. If the pumping has a defined handedness, DNA will be unwound in the centre of the double hexamer. (c) The GINS complex (orange) in conjunction with RecJdbh or GAN (blue) stabilizes an open form of the hexameric MCM and allows extrusion of one DNA strand. (d) Resealing the MCM hexamer traps the displaced strand between the outside of MCM and the GINS assembly. (e) GINS recruits DNA primase (green).
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Figure 1: Model for the initial assembly of the archaeal replisome based on recent advances in the eukaryotic DNA replication field (see [8,9]). (a) A double hexamer of MCM (gray) is loaded on double-stranded DNA at an archaeal replication origin. (b) The two individual hexamers are held together, so that, instead of moving apart, they will pump DNA into the central cavity of the assembly. If the pumping has a defined handedness, DNA will be unwound in the centre of the double hexamer. (c) The GINS complex (orange) in conjunction with RecJdbh or GAN (blue) stabilizes an open form of the hexameric MCM and allows extrusion of one DNA strand. (d) Resealing the MCM hexamer traps the displaced strand between the outside of MCM and the GINS assembly. (e) GINS recruits DNA primase (green).

Mentions: A recent single particle EM reconstruction study by Berger, Botchan and colleagues has revealed the architecture of the eukaryotic Cdc45-MCM(2-7)-GINS complex [8]. The MCM(2-7) complex is shown to form an open ring with a gap between subunits MCM2 and MCM5. Importantly the GINS and Cdc45 proteins bridge across this gap (Figure 1c). In the presence of a non-hydrolyzable analog of ATP, the gate in MCM shuts, forming a dual pore structure, one pore through the centre of the core MCM(2-7) and another formed between GINS/Cdc45 and the outer surface of the MCM (Figure 1). While the fine details of the interactions between GINS and Cdc45 remain to be resolved, it is possibly significant that while the flexible B-domain of Psf1 is not required for GINS complex assembly (mirroring the case with the B-domain of Gins15 in archaea), it is required for formation of the higher order Cdc45-MCM-GINS complex [8].


DNA replication: archaeal oriGINS.

Bell SD - BMC Biol. (2011)

Model for the initial assembly of the archaeal replisome based on recent advances in the eukaryotic DNA replication field (see [8,9]). (a) A double hexamer of MCM (gray) is loaded on double-stranded DNA at an archaeal replication origin. (b) The two individual hexamers are held together, so that, instead of moving apart, they will pump DNA into the central cavity of the assembly. If the pumping has a defined handedness, DNA will be unwound in the centre of the double hexamer. (c) The GINS complex (orange) in conjunction with RecJdbh or GAN (blue) stabilizes an open form of the hexameric MCM and allows extrusion of one DNA strand. (d) Resealing the MCM hexamer traps the displaced strand between the outside of MCM and the GINS assembly. (e) GINS recruits DNA primase (green).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3104950&req=5

Figure 1: Model for the initial assembly of the archaeal replisome based on recent advances in the eukaryotic DNA replication field (see [8,9]). (a) A double hexamer of MCM (gray) is loaded on double-stranded DNA at an archaeal replication origin. (b) The two individual hexamers are held together, so that, instead of moving apart, they will pump DNA into the central cavity of the assembly. If the pumping has a defined handedness, DNA will be unwound in the centre of the double hexamer. (c) The GINS complex (orange) in conjunction with RecJdbh or GAN (blue) stabilizes an open form of the hexameric MCM and allows extrusion of one DNA strand. (d) Resealing the MCM hexamer traps the displaced strand between the outside of MCM and the GINS assembly. (e) GINS recruits DNA primase (green).
Mentions: A recent single particle EM reconstruction study by Berger, Botchan and colleagues has revealed the architecture of the eukaryotic Cdc45-MCM(2-7)-GINS complex [8]. The MCM(2-7) complex is shown to form an open ring with a gap between subunits MCM2 and MCM5. Importantly the GINS and Cdc45 proteins bridge across this gap (Figure 1c). In the presence of a non-hydrolyzable analog of ATP, the gate in MCM shuts, forming a dual pore structure, one pore through the centre of the core MCM(2-7) and another formed between GINS/Cdc45 and the outer surface of the MCM (Figure 1). While the fine details of the interactions between GINS and Cdc45 remain to be resolved, it is possibly significant that while the flexible B-domain of Psf1 is not required for GINS complex assembly (mirroring the case with the B-domain of Gins15 in archaea), it is required for formation of the higher order Cdc45-MCM-GINS complex [8].

Bottom Line: GINS is an essential eukaryotic DNA replication factor that is found in a simplified form in Archaea.A new study in this issue of BMC Biology reveals the first structure of the archaeal GINS complex.The structure reveals the anticipated similarity to the previously determined eukaryotic complex but also has some intriguing differences in the relative disposition of subunit domains.

View Article: PubMed Central - HTML - PubMed

Affiliation: Sir William Dunn School of Pathology, Oxford OX1 3RE, UK. Stephen.bell@path.ox.ac.uk

ABSTRACT
GINS is an essential eukaryotic DNA replication factor that is found in a simplified form in Archaea. A new study in this issue of BMC Biology reveals the first structure of the archaeal GINS complex. The structure reveals the anticipated similarity to the previously determined eukaryotic complex but also has some intriguing differences in the relative disposition of subunit domains.

Show MeSH
Related in: MedlinePlus