histone-fold domain found in DNA polymerase epsilon subunit 4 (POLE4) and similar proteins
POLE4, also called DNA polymerase II subunit 4, or DNA polymerase epsilon subunit p12, may participate in DNA repair and in chromosomal DNA replication. It is an accessory component of the DNA polymerase epsilon complex that consists of four subunits: the catalytic subunit POLE and the accessory subunits POLE2, POLE3 and POLE4. POLE4 forms a complex with POLE3. The POLE3-POLE4 is a histone chaperone that promotes tetrasome formation and DNA supercoiling in vitro. Interaction with POLE3 is a prerequisite for further binding with POLE and POLE2. In fungi, POLE4 has been named as DNA polymerase epsilon subunit C (DPB3, also known as DNA polymerase II subunit C). It is an accessory component of the DNA polymerase epsilon (DNA polymerase II) that participates in chromosomal DNA replication. DNA polymerase epsilon is a heterotetramer consisting of POL2, DPB2, DPB3 and DPB4. DPB3 is required during synthesis of the leading and lagging DNA strands at the replication fork and binds at/or near replication origins and moves along DNA with the replication fork. It has 3'-5' proofreading exonuclease activity that correct errors arising during DNA replication. It is also involved in DNA synthesis during DNA repair. This subfamily also includes protein DLS1 (DPB3-like subunit of ISW2 complex 1). It functions as a component of the ISW2 complex, which at least consists of ISW2, ITC1, DLS1 and DPB4, and acts in remodeling the chromatin by catalyzing an ATP-dependent alteration in the structure of nucleosomal DNA. The ISW2 complex is involved in coordinating transcriptional repression and in inheritance of telomeric silencing. It is involved in repression of MAT a-specific genes, INO1, and early meiotic genes during mitotic growth dependent upon transcription factor UME6 and in a parallel pathway to the RPD3-SIN3 histone deacetylase complex. DLS1 is partially required for the ISW2 complex chromatin remodeling activity and is not required for its interaction with chromatin.
Jiyao W et al.(2023). "The conserved domain database in 2023.",