Nuclear proteins interacting with DNA and tubulin. Study of the interaction of the High Mobility Group protein 1 with tubulin.
Fractionation of a 0.2 M NaCl nuclear extract from rat liver cells by both tubulin and DNA affinity chromatography steps allowed us to find three polypeptides interacting in vitro with both DNA and tubulin. A 22 kDa polypeptide was identified as a proteolytic fragment of High Mobility Group proteins 1 or 2 (HMG 1 or 2). Purified rat liver HMG 1 immobilized on nitrocellulose was found to bind radioiodinated dimeric tubulin through its central B domain. The C domain of HMG 1 appeared to play a negative role in this association process. Soluble HMG 1 depleted of its C-terminal domain interacted with tubulin immobilized on an agarose gel and with microtubules formed from purified tubulin. In contrast, undigested HMG 1 did not interact with tubulin in these conditions. The modification of HMG 1 with amine by 1-ethyl-3-(dimethylaminopropyl)carbodiimide which caused the neutralization of the C domain carboxyl groups restored the ability of HMG 1 to interact with microtubules. These results show that: (a) HMG 1, through its central B domain, binds to both assembled and non-assembled tubulin in vitro and (b) the C-terminal domain of HMG 1 exerts a negative regulatory action on the interaction.
Briolay
A
A
Laboratoire de Physico-chimie Biologique, CNRS EP-19, Université Claude Bernard, Lyon, France.
Rousset
B
B
Roux
B
B
D000818:Animals; D004247:DNA / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000302:isolation & purification / Q000378:metabolism*; D006609:High Mobility Group Proteins / Q000378:metabolism*; D009687:Nuclear Proteins / Q000302:isolation & purification / Q000378:metabolism*; D010446:Peptide Fragments / Q000302:isolation & purification / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D051381:Rats; D013552:Swine; D014404:Tubulin / Q000378:metabolism*
D004268:DNA-Binding Proteins; D006609:High Mobility Group Proteins; D009687:Nuclear Proteins; D010446:Peptide Fragments; D014404:Tubulin; D004247:DNA