High impact information on DPB4

• Both proteins, Dpb4p and Yjl065cp (named Dls1p), contain histone fold motifs and are homologous to the two smallest subunits of ISWI-containing CHRAC complexes in higher eukaryotes [1].
• Furthermore, additional amino acid substitutions to lysines in Dpb4p, to compensate for the loss of positive charges in the Dpb3p mutants, resulted in simultaneous restoration of dsDNA-binding activity by Pol epsilon and telomeric silencing [2].
• DNA polymerase epsilon (pol epsilon) is a multiple subunit complex consisting of at least four proteins, including catalytic Pol2p, Dpb2p, Dpb3p, and Dpb4p [3].
• Both proteins contain histone fold motifs which are present also in S. cerevisiae DPB4 and DPB3 [4].
• A major form of pol epsilon purified from yeast consists of at least four subunits: Pol2p, Dpb2p, Dpb3p, and Dpb4p [5].

Biological context of DPB4

• A deletion mutant of DPB4 (Deltadpb4) is not lethal, but chromosomal DNA replication is slightly disturbed in this mutant [6].
• Structural homologues of DPB4 are present in other eukaryotic genomes, suggesting that the complex structure of S. cerevisiae Polepsilon is conserved in eukaryotes [6].
• This paper reports the partial amino acid sequence of the fourth subunit (Dpb4p) of Polepsilon [6].
• These results strongly suggest that Dpb4p plays an important role in maintaining the complex structure of Polepsilon in S.cerevisiae, even if it is not essential for cell growth [6].

References