Unichrom, a novel nuclear matrix protein, binds to the Ars insulator and canonical MARs.
Eukaryotic genomic DNA is organized into loop structures by attachments to the nuclear matrix. These attachments to the nuclear matrix have been supposed to form the boundaries of chromosomal DNA. Insulators or boundary elements are defined by two characteristics: they interrupt promoter-enhancer communications when inserted between them, and they suppress the silencing of transgenes stably integrated into inactive chromosomal domains. We recently identified an insulator element in the upstream region of the sea urchin arylsulfatase (HpArs) gene that shows both enhancer blocking and suppression of position effects. Here, we report that Unichrom, originally identified by its G-stretch DNA binding capability, is a nuclear matrix protein that binds to the Ars insulator and canonical nuclear matrix attachment regions (MARs). We also show that Unichrom recognizes the minor groove of the AT-rich region within the Ars insulator, which may have a base-unpairing property, as well as the G-stretch DNA. Furthermore, Unichrom selectively interacts with poly(dG).poly(dC), poly(dA).poly(dT) and poly(dAT).poly(dAT), but not with poly(dGC).poly(dGC). Unichrom also shows high affinity for single-stranded G- and C-stretches. We discuss the DNA binding motif of Unichrom and the function of Unichrom in the nuclear matrix.
Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan.
Hideki
H
Tagashira
Taishin
T
Shimotori
Naoaki
N
Sakamoto
Masato
M
Katahira
Yohei
Y
Miyanoiri
Takashi
T
Yamamoto
Keiko
K
Mitsunaga-Nakatsubo
Hiraku
H
Shimada
Shinichiro
S
Kusunoki
Koji
K
Akasaka
D000818:Animals; D001192:Arylsulfatases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D004268:DNA-Binding Proteins / Q000378:metabolism; D038101:Insulator Elements / Q000235:genetics / Q000502:physiology*; D008969:Molecular Sequence Data; D015530:Nuclear Matrix / Q000378:metabolism*; D034521:Nuclear Matrix-Associated Proteins / Q000378:metabolism*; D012617:Sea Urchins / Q000201:enzymology / Q000235:genetics*
D004268:DNA-Binding Proteins; D034521:Nuclear Matrix-Associated Proteins; D001192:Arylsulfatases