Spotlight on the Replisome: Aetiology of DNA Replication-Associated Genetic Diseases

DNA replication is performed by a multiprotein complex known as the ‘replisome,’ which assembled and regulated in cell cycle–dependent manner.Hypomorphic mutations of components replisome lead to defective development, reduced growth, altered tissue homeostasis.Whole-genome sequencing studies significantly expanded repertoire mendelian diseases caused mutation machinery.Phenotypic analysis mechanistic support origin assembly activation perturbation fork stability pathogenetic mechanisms replication-linked human genetic diseases. Human development homeostasis depend on control cellular proliferation differentiation. essential couple genome duplication division with establishment maintenance differentiation programs. In eukaryotes, large machine strictly cycle-dependent manner. Inherited have been identified range conditions characterised developmental abnormalities organismal growth addition an involvement immune endocrine systems and/or heightened tumour predisposition. Here, we review current knowledge molecular genetics dysfunction disorders discuss recent insights into their pathogenesis, focus specific steps affected these Efficient accurate for accomplishment programs mammals. vivo vitro budding yeast other lower eukaryotes provided clear understanding key involved execution [1.Bell S.P. Labib K. Chromosome Saccharomyces cerevisiae.Genetics. 2016; 203: 1027-1067Crossref PubMed Google Scholar]. Although redundancy has emerged during evolution higher basic players that perform appear be remarkably conserved. Over last two decades, many mammalian machinery functionally characterised. Proteomic also several mammalian-specific factors stably or transiently associated (see Glossary), particularly presence stress, prominent role maintaining health [2.Dungrawala H. et al.The checkpoint prevents types collapse without regulating stability.Mol. 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The first step takes place G1 phase cycle, when origins ‘licensed’ sequential recognition 1–6 (ORC1–6) together 6 (CDC6) Cdc10-dependent transcript (CDT1), promote loading inactive mini-chromosome 2–7 (MCM2–7) double hexamers at [4.Riera A. al.From structure mechanism-understanding initiation replication.Genes Dev. 31: 1073-1088Crossref (0) Scholar] Historically, licensing pre-replication (PRE-RC) Scholar].Box 1Mechanisms Control Origin Licensing ActivationSophisticated evolved major replication, from PRE-RC formation Defects any one can congenital Regulation crucial integrity. Accordingly, MCM2–7 chromatin limited overall levels localisation ORC1–6, CDC6, CDT1 [110.Arias E.E. Walter J.C. 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Cell 16: 360-374Crossref sequence features recently regulators metazoans, flexibility usage couples function (e.g., transcriptional programs) this, series marks, including histone acetylation methylation, Finally, temporally prevent exhaustion dNTPs allow complete before transition G2/M Sophisticated Early Importantly, replication. Initiation At G1–S transition, Dbf4-dependent kinase (DDK) cyclin-dependent (CDK) events drive processive helicase CMG, comprises CDC45, MCM2–7, Go-Ichi-Ni-San (GINS) (composed PSF1, PSF2, PSF3, SLD5; ‘GINS1–4’ mammals [5.Moyer S.E. al.Isolation Cdc45/Mcm2-7/GINS (CMG) complex, candidate helicase.Proc. 103: 10236-10241Crossref (501) Scholar]). MCMs represent CDKs phosphorylate pre-initiation TopBP1-interacting regulator (TICRR)/TRESLIN RECQ-like 4 (RECQL4; Sld3 Sld2 yeast), allowing BRCT-dependent topoisomerase II–binding protein (TOPBP1; Dpb11 cerevisiae) recruitment CDC45 GINS1–4 concert polymerase epsilon (Pol ?) [6.Zegerman P. Diffley J.F.X. 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Replication A (RPA) recruited resulting single-stranded (ssDNA), replisomes established, translocate along ssDNA 3?–5? direction [12.Douglas M.E. mechanism activation.Nature. 2018; 555: 265-268Crossref (62) Scholar,13.Fu Y.V. al.Selective bypass lagging strand roadblock helicase.Cell. 2011; 146: 931-941Abstract (243) After POL?-dependent synthesis short RNA-DNA primers, strands extended conserved polymerases POL? POL? [14.Burgers P.M.J. Kunkel T.A. Eukaryotic fork.Annu. Biochem. 86: 417-438Crossref (148) 2). reconstitution well proteomic evidence established that, unchallenged synthesises whereas responsible extension indirectly tethered fork, POL? appears physically coupled AND-1/CTF4 trimer, ‘hub’ links CTF4-interacting peptide (CIP) box–containing [15.Villa F. al.Ctf4 hub CIP-box helicase.Mol. 63: 385-396Abstract Other C1–5 (RFC1–5) chromosome transmission fidelity 18 (CTF18)–RFC2–5 complexes (or clamp loaders), proliferating nuclear antigen (PCNA), trimeric scaffold encircles ssDNA–dsDNA junctions efficient Upon lagging-strand POL?, 5? flap structures generated processed structure–specific endonuclease (FEN1) helicase/nuclease 2 (DNA2; long flaps) 1–mediated ligation end products CLASPIN (Mrc1 TIPIN/TIMELESS heterodimer (homologues Csm3/Tof1) engage unperturbed perturbed termination occurs stochastically convergence, ubiquitylation-dependent disassembly (Box 2).Box 2Termination ReplicationAssembly studied extensively. 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Assembly