Experts identify proteins that regulate dual processes

According to recent research, the protein UBR7 acts as a histone chaperone and controls histone re-deposition at certain sites at the time of DNA replication. The research was published in The EMBO Journal.

Daniel Foltz, PhD, associate professor of Biochemistry and Molecular Genetics, was senior author of the study published in The EMBO Journal. Image Credit: Northwestern University Feinberg School of Medicine.

According to Daniel Foltz Ph.D., associate professor of Biochemistry and Molecular Genetics, and the senior author of the study, this protein was earlier known to control nucleotide metabolism, thus making UBR7 one among the first proteins known to impact both processes.

We’ve thought of these processes as co-incident but independent, however, this is the first mechanism where we can say they are somehow coupled.”

Daniel Foltz, Study Senior Author and Associate Professor, Biochemistry and Molecular Genetics, Northwestern University Feinberg School of Medicine

Cells that are proliferation—dividing and replicating—should replicate their DNA to offer a genetic template for the new cell. This involves nucleotide synthesis and packaging of new DNA into chromatin. Histone chaperone proteins make sure that the old and new histones—spools around which DNA is looped—are deposited correctly, or recycled and re-deposited, respectively.

Foltz and his associates, in the current research, analyzed the binding of UBR7. They identified that it binds to histones with a specific epigenetic marker. The marker—one that is linked with gene promoters—is only attached to histones that are packaged into chromatin. This makes UBR7 one of the first histone chaperones known to control recycled histones, instead of fresh histones.

Producing cells without UBR7 obstructed the redeposition of these particular histones.

If the cell marks a histone and then gets rid of it during replication, then it’s lost that epigenetic information. The cell has ways to ensure that you can put those modified histones right back, to ensure that information is retained. It’s a memory of the state of the gene before DNA replication.”

Daniel Foltz, Study Senior Author and Associate Professor, Biochemistry and Molecular Genetics, Northwestern University Feinberg School of Medicine

According to Foltz what makes UBR7 interesting is that it has a known function: controlling nucleotide metabolism. UBR7 interacts with proteins that form the basic building block of DNA and RNA, increasing the possibility that it performs a coordinating role for both processes.

It might be a way for the cell to ensure that not only does it have enough building blocks to create DNA, but that it also has enough building blocks to build chromatin.”

Daniel Foltz, Study Senior Author and Associate Professor, Biochemistry and Molecular Genetics, Northwestern University Feinberg School of Medicine

The researchers intend to analyze other histone chaperone proteins, investigating other dual-use proteins.

Foltz concludes, “This coordination probably involves other chaperones besides just UBR7.”