Binding of the protein disulfide isomerase isoform ERp60 to the nuclear matrix-associated regions of DNA

Protein ERp60, previously found in the internal nuclear matrix in chicken liver nuclei, is a member of the protein disulfide isomerase family. It binds DNA and double helical polynucleotides in vitro with a preferential recognition toward the matrix‐associated regions of DNA and poly(dA)·poly(dT), and its binding is inhibited by distamycin. ERp60 can be cross‐linked chemically to DNA in the intact nuclei, suggesting that its association with DNA is present in vivo. As a whole, these results indicate that ERp60 is a component of the subset of nuclear matrix proteins that are responsible for the attachment of DNA to the nuclear matrix and for the formation of DNA loops. A distinctive feature of this protein, which has two thioredoxin‐like sites, is that its affinity to poly(dA)·poly(dT) is strongly dependent on its redox state. Only its oxidized form, in fact, does it bind poly(dA)·poly(dT). The hypothesis can be made that through the intervention of ERp60, the redox state of the nucleus influences the formation or the stability of some selected nuclear matrix–DNA interactions. J. Cell. Biochem. 72:528–539, 1999. © 1999 Wiley‐Liss, Inc.