scholarly journals The Methanothermobacter thermautotrophicus Cdc6-2 Protein, the Putative Helicase Loader, Dissociates the Minichromosome Maintenance Helicase

2008 ◽  
Vol 190 (11) ◽  
pp. 4091-4094 ◽  
Author(s):  
Jae-Ho Shin ◽  
Gun Young Heo ◽  
Zvi Kelman
Keyword(s):  
Minichromosome Maintenance ◽  
Mcm Helicase ◽  
Protein Functions ◽  
Mcm Complex ◽  
Methanothermobacter Thermautotrophicus

ABSTRACT The Cdc6-1 and -2 proteins from the archaeon Methanothermobacter thermautotrophicus were previously shown to bind the minichromosome maintenance (MCM) helicase. It is shown here that Cdc6-2 protein dissociates the MCM complex. This observation supports the hypothesis that the Cdc6-2 protein functions as a helicase loader.

scholarly journals DNA Binding by the Methanothermobacter thermautotrophicus Cdc6 Protein Is Inhibited by the Minichromosome Maintenance Helicase

2006 ◽  
Vol 188 (12) ◽  
pp. 4577-4580 ◽  
Author(s):  
Rajesh Kasiviswanathan ◽  
Jae-Ho Shin ◽  
Zvi Kelman
Keyword(s):  
Dna Binding ◽  
Binding Activity ◽  
Minichromosome Maintenance ◽  
Single Stranded Dna ◽  
Mutant Proteins ◽  
Dna Binding Activity ◽  
Double Stranded Dna ◽  
Mcm Helicase ◽  
Methanothermobacter Thermautotrophicus

ABSTRACT The Cdc6 proteins from the archaeon Methanothermobacter thermautotrophicus were previously shown to bind double-stranded DNA. It is shown here that the proteins also bind single-stranded DNA. Using minichromosome maintenance (MCM) helicase mutant proteins unable to bind DNA, it was found that the interaction of MCM with Cdc6 inhibits the DNA binding activity of Cdc6.

The MCM complex: (just) a replicative helicase?

2008 ◽  
Vol 36 (1) ◽  
pp. 136-140 ◽  
Author(s):  
Alessandro Costa ◽  
Silvia Onesti
Keyword(s):  
Minichromosome Maintenance ◽  
Replicative Helicase ◽  
Aaa Atpase ◽  
Mcm Helicase ◽  
Eukaryotic Dna ◽  
Mcm Complex ◽  
Elongation Step ◽  
Hexameric Helicases

The MCM2–MCM7 (minichromosome maintenance 2–7) complex is involved both in the initiation and the elongation step of eukaryotic DNA replication and is believed to be the replicative helicase. Whereas the mechanism of DNA unwinding at the replication fork has been extensively investigated, the role of the MCM2–MCM7 complex during initiation has not yet been characterized by biochemical studies. Here we summarize the in vivo evidence which supports a role for the MCM complex in origin melting. In addition, we present an overview of the mechanism of action of a number of AAA+ (ATPase associated with various cellular activities) initiators and hexameric helicases, which can be used in turn as models for the steps of recognition, duplex melting, loading and nucleic acid translocation of the MCM helicase.

scholarly journals Regulation of Geminin Functions by Cell Cycle-Dependent Nuclear-Cytoplasmic Shuttling

2007 ◽  
Vol 27 (13) ◽  
pp. 4737-4744 ◽  
Author(s):  
Lingfei Luo ◽  
Yvonne Uerlings ◽  
Nicole Happel ◽  
Naisana S. Asli ◽  
Hendrik Knoetgen ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Protein Degradation ◽  
Gene Transcription ◽  
S Phase ◽  
Minichromosome Maintenance ◽  
Protein Functions ◽  
Mcm Complex ◽  
Cycle Dependent ◽  
Dna Rereplication

ABSTRACT The geminin protein functions both as a DNA rereplication inhibitor through association with Cdt1 and as a repressor of Hox gene transcription through the polycomb pathway. Here, we report that the functions of avian geminin are coordinated with and regulated by cell cycle-dependent nuclear-cytoplasmic shuttling. In S phase, geminin enters nuclei and inhibits both loading of the minichromosome maintenance (MCM) complex onto chromatin and Hox gene transcription. At the end of mitosis, geminin is exported from nuclei by the exportin protein Crm1 and is unavailable in the nucleus during the next G1 phase, thus ensuring proper chromatin loading of the MCM complex and Hox gene transcription. This mechanism for regulating the functions of geminin adds to distinct mechanisms, such as protein degradation and ubiquitination, applied in other vertebrates.

scholarly journals Archaeal Minichromosome Maintenance (MCM) Helicase Can Unwind DNA Bound by Archaeal Histones and Transcription Factors

2006 ◽  
Vol 282 (7) ◽  
pp. 4908-4915 ◽  
Author(s):  
Jae-Ho Shin ◽  
Thomas J. Santangelo ◽  
Yunwei Xie ◽  
John N. Reeve ◽  
Zvi Kelman
Keyword(s):  
Rna Polymerase ◽  
Tata Box ◽  
Replication Forks ◽  
Minichromosome Maintenance ◽  
Dna Complexes ◽  
Mcm Helicase ◽  
Methanothermobacter Thermautotrophicus ◽  
Tata Box Binding Protein ◽  
Protein Transcription ◽  
Archaeal Histone

Protein-DNA complexes must be disassembled to facilitate DNA replication. Replication forks contain a helicase that unwinds the duplex DNA at the front of the fork. The minichromosome maintenance helicase from the archaeon Methanothermobacter thermautotrophicus required only ATP to unwind DNA bound into complexes by the M. thermautotrophicus archaeal histone HMtA2, transcription repressor TrpY, or into a transcription pre-initiation complex by M. thermautotrophicus TATA-box-binding protein, transcription factor B, and RNA polymerase. In contrast, the minichromosome maintenance helicase was unable to unwind DNA bound by this archaeal RNA polymerase in a stalled transcript-elongating complex.

scholarly journals Drosophila Minichromosome Maintenance 6 Is Required for Chorion Gene Amplification and Genomic Replication

2002 ◽  
Vol 13 (2) ◽  
pp. 607-620 ◽  
Author(s):  
Gina Schwed ◽  
Noah May ◽  
Yana Pechersky ◽  
Brian R. Calvi
Keyword(s):  
Cell Cycle ◽  
Dna Replication ◽  
Genetic Dissection ◽  
Minichromosome Maintenance ◽  
Multiple Origins ◽  
Origin Licensing ◽  
Mcm Complex ◽  
Mcm Proteins ◽  
Prereplicative Complex ◽  
Cycle Regulation

Duplication of the eukaryotic genome initiates from multiple origins of DNA replication whose activity is coordinated with the cell cycle. We have been studying the origins of DNA replication that control amplification of eggshell (chorion) genes duringDrosophila oogenesis. Mutation of genes required for amplification results in a thin eggshell phenotype, allowing a genetic dissection of origin regulation. Herein, we show that one mutation corresponds to a subunit of the minichromosome maintenance (MCM) complex of proteins, MCM6. The binding of the MCM complex to origins in G1 as part of a prereplicative complex is critical for the cell cycle regulation of origin licensing. We find that MCM6 associates with other MCM subunits during amplification. These results suggest that chorion origins are bound by an amplification complex that contains MCM proteins and therefore resembles the prereplicative complex. Lethal alleles of MCM6 reveal it is essential for mitotic cycles and endocycles, and suggest that its function is mediated by ATP. We discuss the implications of these findings for the role of MCMs in the coordination of DNA replication during the cell cycle.

scholarly journals Structural Changes in Mcm5 Protein Bypass Cdc7-Dbf4 Function and Reduce Replication Origin Efficiency in Saccharomyces cerevisiae

2007 ◽  
Vol 27 (21) ◽  
pp. 7594-7602 ◽  
Author(s):  
Margaret L. Hoang ◽  
Ronald P. Leon ◽  
Luis Pessoa-Brandao ◽  
Sonia Hunt ◽  
M. K. Raghuraman ◽  
...  
Keyword(s):  
Structural Changes ◽  
S Phase ◽  
Minichromosome Maintenance ◽  
Chromosomal Replication ◽  
Origin Firing ◽  
Highly Active ◽  
Mcm Complex ◽  
Alternate States ◽  
Firing Efficiency ◽  
Intrinsic Firing

ABSTRACT Eukaryotic chromosomal replication is a complicated process with many origins firing at different efficiencies and times during S phase. Prereplication complexes are assembled on all origins in G1 phase, and yet only a subset of complexes is activated during S phase by DDK (for Dbf4-dependent kinase) (Cdc7-Dbf4). The yeast mcm5-bob1 (P83L) mutation bypasses DDK but results in reduced intrinsic firing efficiency at 11 endogenous origins and at origins located on minichromosomes. Origin efficiency may result from Mcm5 protein assuming an altered conformation, as predicted from the atomic structure of an archaeal MCM (for minichromosome maintenance) homologue. Similarly, an intragenic mutation in a residue predicted to interact with P83L suppresses the mcm5-bob1 bypass phenotype. We propose DDK phosphorylation of the MCM complex normally results in a single, highly active conformation of Mcm5, whereas the mcm5-bob1 mutation produces a number of conformations, only one of which is permissive for origin activation. Random adoption of these alternate states by the mcm5-bob1 protein can explain both how origin firing occurs independently of DDK and why origin efficiency is reduced. Because similar mutations in mcm2 and mcm4 cannot bypass DDK, Mcm5 protein may be a unique Mcm protein that is the final target of DDK regulation.

scholarly journals Polymorphism and Double Hexamer Structure in the Archaeal Minichromosome Maintenance (MCM) Helicase fromMethanobacterium thermoautotrophicum

2005 ◽  
Vol 280 (49) ◽  
pp. 40909-40915 ◽  
Author(s):  
Yacob Gómez-Llorente ◽  
Ryan J. Fletcher ◽  
Xiaojiang S. Chen ◽  
José M. Carazo ◽  
Carmen San Martín
Keyword(s):  
Minichromosome Maintenance ◽  
Mcm Helicase

scholarly journals The interplay of DNA binding, ATP hydrolysis and helicase activities of the archaeal MCM helicase

2011 ◽  
Vol 436 (2) ◽  
pp. 409-414 ◽  
Author(s):  
Li Phing Liew ◽  
Stephen D. Bell
Keyword(s):  
Dna Binding ◽  
Active Site ◽  
Atp Hydrolysis ◽  
Sulfolobus Solfataricus ◽  
Active Form ◽  
Dna Helicase ◽  
Atpase Domain ◽  
Minichromosome Maintenance ◽  
Conserved Residues ◽  
Mcm Helicase

The MCM (minichromosome maintenance) proteins of archaea are widely believed to be the replicative DNA helicase of these organisms. Most archaea possess a single MCM orthologue that forms homo-multimeric assemblies with a single hexamer believed to be the active form. In the present study we characterize the roles of highly conserved residues in the ATPase domain of the MCM of the hyperthermophilic archaeon Sulfolobus solfataricus. Our results identify a potential conduit for communicating DNA-binding information to the ATPase active site.

scholarly journals Mutations in Subdomain B of the Minichromosome Maintenance (MCM) Helicase Affect DNA Binding and Modulate Conformational Transitions

2008 ◽  
Vol 284 (9) ◽  
pp. 5654-5661 ◽  
Author(s):  
Elizabeth R. Jenkinson ◽  
Alessandro Costa ◽  
Andrew P. Leech ◽  
Ardan Patwardhan ◽  
Silvia Onesti ◽  
...  
Keyword(s):  
Dna Binding ◽  
Conformational Transitions ◽  
Minichromosome Maintenance ◽  
Mcm Helicase
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