SNAP output for PDB entry 5b7j [SNAP web server]

PDB-id

5b7j; SNAP-derived features in text and JSON formats; DNAproDB

Class

DNA binding protein-DNA

Method

NMR

Summary

Structure model of sap1-DNA complex

Reference

Guan L, He P, Yang F, Zhang Y, Hu Y, Ding J, Hua Y, Zhang Y, Ye Q, Hu J, Wang T, Jin C, Kong D (2017): "Sap1 is a replication-initiation factor essential for the assembly of pre-replicative complex in the fission yeast Schizosaccharomyces pombe." J. Biol. Chem., 292, 6056-6075. doi: 10.1074/jbc.M116.767806.

Abstract

A central step in the initiation of chromosomal DNA replication in eukaryotes is the assembly of pre-replicative complex (pre-RC) at late M and early G1 phase of the cell cycles. Since 1973, four proteins or protein complexes, including cell division control protein 6 (Cdc6)/Cdc18, minichromosome maintenance protein complex, origin recognition complex (ORC), and Cdt1, are known components of the pre-RC. Previously, we reported that a non-ORC protein binds to the essential element Δ9 of the Schizosaccharomyces pombe DNA-replication origin ARS3001. In this study, we identified that the non-ORC protein is Sap1. Like ORC, Sap1 binds to DNA origins during cell growth cycles. But unlike ORC, which binds to asymmetric AT-rich sequences through its nine AT-hook motifs, Sap1 preferentially binds to a DNA sequence of 5'-(A/T) n (C/G)(A/T)9-10(G/C)(A/T) n -3' (n ≥ 1). We also found that Sap1 and ORC physically interact. We further demonstrated that Sap1 is required for the assembly of the pre-RC because of its essential role in recruiting Cdc18 to DNA origins. Thus, we conclude that Sap1 is a replication-initiation factor that directly participates in the assembly of the pre-RC. DNA-replication origins in fission yeast are defined by possessing two essential elements with one bound by ORC and the other by Sap1.