Simultaneous ternary extension of DNA catalyzed by a trimeric replicase assembled in vivo.
According to current models, dimeric DNA Polymerases coordinate the replication of DNA leading and lagging strands. However, it was recently shown that trimeric DNA Polymerases, assembled in vitro, replicate the lagging strand more efficiently than dimeric replicases. Here we show that the τ, α, ε, and θ subunits of Escherichia coli DNA Polymerase III can be assembled in vivo, yielding the trimeric τ3α3ε3θ3 complex. Further, we propose a molecular model of this complex, whose catalytic action was investigated using model DNA substrates. Our observations indicate that trimeric DNA replicases reduce the gap between leading and lagging strand synthesis.
Department of Pharmacy and Biotechnology, University of Bologna, Viale Risorgimento 4, 40136 Bologna, Italy.
Alejandro
A
Montón Silva
Department of Pharmacy and Biotechnology, University of Bologna, Viale Risorgimento 4, 40136 Bologna, Italy.
Fabio
F
Lapenta
Department of Pharmacy and Biotechnology, University of Bologna, Viale Risorgimento 4, 40136 Bologna, Italy; CSGI, University of Firenze, Via della Lastruccia 3, 50019 Sesto Fiorentino, FI, Italy.
Alessandra
A
Stefan
Department of Pharmacy, University of Salerno, Via Giovanni Paolo II 132, 84084 Fisciano, SA, Italy.
Fabrizio
F
Dal Piaz
Department of Pharmacy and Biotechnology, University of Bologna, Viale Risorgimento 4, 40136 Bologna, Italy.
Alessandro
A
Ceccarelli
Department of Pharmacy and Biotechnology, University of Bologna, Viale Risorgimento 4, 40136 Bologna, Italy.
Alessandro
A
Perrone
Department of Pharmacy and Biotechnology, University of Bologna, Viale Risorgimento 4, 40136 Bologna, Italy; CSGI, University of Firenze, Via della Lastruccia 3, 50019 Sesto Fiorentino, FI, Italy. Electronic address: a.hochkoeppler@unibo.it.
Alejandro
A
Hochkoeppler
D001483:Base Sequence; D055162:Biocatalysis; D004258:DNA Polymerase III / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004261:DNA Replication; D004269:DNA, Bacterial / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D011485:Protein Binding; D055503:Protein Multimerization; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D021122:Protein Subunits; D004258:DNA Polymerase III
DNA Polymerase III; E. coli; Trimeric DNA Polymerase; Triple DNA extension; τ(3)α(3)ε(3)θ(3) complex