High impact information on DPB2

• DPB11, a gene that suppresses mutations in two essential subunits of Saccharomyces cerevisiae DNA polymerase II(epsilon) encoded by POL2 and DPB2, was isolated on a multicopy plasmid [1].
• The DPB2 transcript periodically fluctuated during the cell cycle and, like those of other genes encoding DNA replication proteins, peaked at the G1/S phase boundary [2].
• DPB2, the gene encoding DNA polymerase II subunit B, is required for chromosome replication in Saccharomyces cerevisiae [2].
• Finally, inactivation of all three CDK consensus sites in Dpb2 results in a synthetic phenotype with the pol2-11 mutation, leading to decreased spore viability, slow growth, and increased thermosensitivity [3].
• DNA polymerase epsilon (pol epsilon) is a multiple subunit complex consisting of at least four proteins, including catalytic Pol2p, Dpb2p, Dpb3p, and Dpb4p [4].

Biological context of DPB2

• The level of DPB3 transcript thus appears to be under the same cell cycle control as those of POL2, DPB2 and other DNA replication genes [5].
• DNA polymerase II purified from Saccharomyces cerevisiae contains polypeptides with apparent molecular masses of greater than 200, 80, 34, 30 and 29 kDa, the two largest of which (subunits A and B) are encoded by the essential genes POL2 and DPB2 [5].
• We suggest that phosphorylation of Dpb2 during late G(1) phase at CDK consensus sites facilitates the interaction with Pol2 or the activity of Polepsilon[3]
• The pol2-E and pol2-F mutations that cause replication defects in vivo weaken the interaction between Pol2p and Dpb2p and also reduce dimerization of Pol2p [6].

Analytical, diagnostic and therapeutic context of DPB2

• Neither Dpb3p nor Dpb2p homodimerizes in the two-hybrid assay [7].
• Using site-directed mutagenesis, we show that Ser-144 is sufficient for the formation of the lower mobility form of Dpb2 in vivo [3].

References