Phosphorylation of the DNA-binding domain of nonhistone high-mobility group I protein by cdc2 kinase: Reduction of binding affinity

Journal Article · Fri Mar 01 00:00:00 EST 1991 · Proceedings of the National Academy of Sciences of the United States of America; (United States)

DOI:https://doi.org/10.1073/pnas.88.5.1671· OSTI ID:6203324

Reeves, R; Nissen, M S ^[1]; Langan, T A ^[2]

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1. Washington State Univ., Pullman (United States)
2. Univ. of Colorado, Denver (United States)

Mammalian high-mobility group I nonhistone protein (HMG-I) is a DNA-binding chromatin protein that has been demonstrated both in vitro and in vivo to be localized to the A + T-rich sequenced of DNA. Recently an unusual binding domain peptide, the A{center dot}T-hook motif, that mediates specific interaction of HMG-I with the minor groove of DNA in vitro has been described. Inspection of the A{center dot}T-hook region of the binding domain showed that it matches the consensus sequence for phosphorylation by cdc2 kinase. Here the authors demonstrate that HMG-I is a substrate for phosphorylation by purified mammalian cdc2 kinase in vitro. The site of phosphorylation by this enzyme is a threonine residue at the amino-terminal end of the principal binding-domain region of the protein. Labeling of mitotically blocked mouse cells with ({sup 32}P)phosphate demonstrates that this same threonine residue in HMG-I is also preferentially phosphorylated in vivo. These finding indicate that cdc2 phosphorylation may significantly alter the DNA-binding properties of the HMG-I proteins. Becuase many cdc2 substrated are DNA-binding proteins, these results further suggest that alteration of the DNA-binding affinity of a variety of proteins is an important general component of the mechanism by which cdc2 kinase regulates cell cycle progression.

• OSTI ID: 6203324
• Journal Information: Proceedings of the National Academy of Sciences of the United States of America; (United States), Vol. 88:5; ISSN 0027-8424
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
CHROMATIN
PHOSPHORYLATION
PHOSPHOTRANSFERASES
BIOCHEMISTRY
PHOSPHORUS 32
PURIFICATION
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CHEMICAL REACTIONS
CHEMISTRY
DAYS LIVING RADIOISOTOPES
ENZYMES
ISOTOPES
LIGHT NUCLEI
NUCLEI
ODD-ODD NUCLEI
PHOSPHORUS ISOTOPES
PHOSPHORUS-GROUP TRANSFERASES
RADIOISOTOPES
TRANSFERASES
550201* - Biochemistry- Tracer Techniques