Identification and characterization of the DNA replication origin recognition complex gene family in the silkworm Bombyx mori

2011 ◽  
Vol 31 (5) ◽  
pp. 353-361 ◽  
Author(s):  
Hui-Peng Yang ◽  
Su-Juan Luo ◽  
Yi-Nü Li ◽  
Yao-Zhou Zhang ◽  
Zhi-Fang Zhang
Keyword(s):  
Dna Replication ◽  
Bombyx Mori ◽  
Replication Origin ◽  
Origin Recognition Complex ◽  
Bioinformatic Analysis ◽  
Replication Complex ◽  
Dna Replication Origin ◽  
Rapid Amplification ◽  
Replication Factors ◽  
Origin Recognition

The ORC (origin recognition complex) binds to the DNA replication origin and recruits other replication factors to form the pre-replication complex. The cDNA and genomic sequences of all six subunits of ORC in Bombyx mori (BmORC1–6) were determined by RACE (rapid amplification of cDNA ends) and bioinformatic analysis. The conserved domains were identified in BmOrc1p–6p and the C-terminal of BmOrc6p features a short sequence that may be specific for Lepidoptera. As in other organisms, each of the six BmORC subunits had evolved individually from ancestral genes in early eukaryotes. During embryo development, the six genes were co-regulated, but different ratios of the abundance of mRNAs were observed in 13 tissues of the fifth instar day-6 larvae. Infection by BmNPV (B. mori nucleopolyhedrovirus) initially decreased and then increased the abundance of BmORC. We suggest that some of the BmOrc proteins may have additional functions and that BmOrc proteins participate in the replication of BmNPV.

Structure of the origin recognition complex bound to DNA replication origin

Nature ◽  
2018 ◽  
Vol 559 (7713) ◽  
pp. 217-222 ◽  
Author(s):  
Ningning Li ◽  
Wai Hei Lam ◽  
Yuanliang Zhai ◽  
Jiaxuan Cheng ◽  
Erchao Cheng ◽  
...  
Keyword(s):  
Dna Replication ◽  
Replication Origin ◽  
Origin Recognition Complex ◽  
Dna Replication Origin ◽  
Origin Recognition

scholarly journals Structural basis of DNA replication origin recognition by human Orc6 protein binding with DNA

2020 ◽  
Vol 48 (19) ◽  
pp. 11146-11161
Author(s):  
Naining Xu ◽  
Yingying You ◽  
Changdong Liu ◽  
Maxim Balasov ◽  
Lee Tung Lun ◽  
...  
Keyword(s):  
Dna Replication ◽  
Dna Binding ◽  
Solution Structure ◽  
Origin Recognition Complex ◽  
Structural Basis ◽  
Dna Replication Origin ◽  
Dna Alterations ◽  
Replication Initiator ◽  
Binding Subunit ◽  
Origin Recognition

Abstract The six-subunit origin recognition complex (ORC), a DNA replication initiator, defines the localization of the origins of replication in eukaryotes. The Orc6 subunit is the smallest and the least conserved among ORC subunits. It is required for DNA replication and essential for viability in all species. Orc6 in metazoans carries a structural homology with transcription factor TFIIB and can bind DNA on its own. Here, we report a solution structure of the full-length human Orc6 (HsOrc6) alone and in a complex with DNA. We further showed that human Orc6 is composed of three independent domains: N-terminal, middle and C-terminal (HsOrc6-N, HsOrc6-M and HsOrc6-C). We also identified a distinct DNA-binding domain of human Orc6, named as HsOrc6-DBD. The detailed analysis of the structure revealed novel amino acid clusters important for the interaction with DNA. Alterations of these amino acids abolish DNA-binding ability of Orc6 and result in reduced levels of DNA replication. We propose that Orc6 is a DNA-binding subunit of human/metazoan ORC and may play roles in targeting, positioning and assembling the functional ORC at the origins.

scholarly journals Changes in association of the Xenopus origin recognition complex with chromatin on licensing of replication origins

1999 ◽  
Vol 112 (12) ◽  
pp. 2011-2018 ◽  
Author(s):  
A. Rowles ◽  
S. Tada ◽  
J.J. Blow
Keyword(s):  
Dna Replication ◽  
Single Molecule ◽  
Replication Origin ◽  
Origin Recognition Complex ◽  
S Phase ◽  
Replication Origins ◽  
Free System ◽  
Essential Function ◽  
Initiation Of Dna Replication ◽  
Origin Recognition

During late mitosis and early G1, a series of proteins are assembled onto replication origins that results in them becoming ‘licensed’ for replication in the subsequent S phase. In Xenopus this first involves the assembly onto chromatin of the Xenopus origin recognition complex XORC, and then XCdc6, and finally the RLF-M component of the replication licensing system. In this paper we examine changes in the way that XORC associates with chromatin in the Xenopus cell-free system as origins become licensed. Restricting the quantity of XORC on chromatin reduced the extent of replication as expected if a single molecule of XORC is sufficient to specify a single replication origin. During metaphase, XOrc1 associated only weakly with chromatin. In early interphase, XOrc1 formed a strong complex with chromatin, as evidenced by its resistance to elution by 200 mM salt, and this state persisted when XCdc6 was assembled onto the chromatin. As a consequence of origins becoming licensed the association of XOrc1 and XCdc6 with chromatin was destabilised, and XOrc1 became susceptible to removal from chromatin by exposure to either high salt or high Cdk levels. At this stage the essential function for XORC and XCdc6 in DNA replication had already been fulfilled. Since high Cdk levels are required for the initiation of DNA replication, this ‘licensing-dependent origin inactivation’ may contribute to mechanisms that prevent re-licensing of replication origins once S phase has started.

Structural Basis of DNA Replication Origin Recognition by an ORC Protein

Science ◽  
2007 ◽  
Vol 317 (5842) ◽  
pp. 1213-1216 ◽  
Author(s):  
M. Gaudier ◽  
B. S. Schuwirth ◽  
S. L. Westcott ◽  
D. B. Wigley
Keyword(s):  
Dna Replication ◽  
Replication Origin ◽  
Structural Basis ◽  
Dna Replication Origin ◽  
Origin Recognition

scholarly journals Identification of a Preinitiation Step in DNA Replication That Is Independent of Origin Recognition Complex and cdc6, but Dependent on cdk2

1998 ◽  
Vol 140 (2) ◽  
pp. 271-281 ◽  
Author(s):  
Xuequn Helen Hua ◽  
John Newport
Keyword(s):  
Dna Replication ◽  
Origin Recognition Complex ◽  
Minichromosome Maintenance ◽  
Cdk2 Activity ◽  
Proteolytic Pathway ◽  
Egg Extracts ◽  
Dna Replication Origin ◽  
Initiation Of Dna Replication ◽  
Mcm Proteins ◽  
Origin Recognition

Before initiation of DNA replication, origin recognition complex (ORC) proteins, cdc6, and minichromosome maintenance (MCM) proteins bind to chromatin sequentially and form preinitiation complexes. Using Xenopus laevis egg extracts, we find that after the formation of these complexes and before initiation of DNA replication, cdc6 is rapidly removed from chromatin, possibly degraded by a cdk2-activated, ubiquitin-dependent proteolytic pathway. If this displacement is inhibited, DNA replication fails to initiate. We also find that after assembly of MCM proteins into preinitiation complexes, removal of the ORC from DNA does not block the subsequent initiation of replication. Importantly, under conditions in which both ORC and cdc6 protein are absent from preinitiation complexes, DNA replication is still dependent on cdk2 activity. Therefore, the final steps in the process leading to initiation of DNA replication during S phase of the cell cycle are independent of ORC and cdc6 proteins, but dependent on cdk2 activity.

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