ISOLATION AND CHARACTERIZATION OF A 28-KDA HMG-LIKE PROTEIN THAT BINDS TO A T-RICH DISTAL PROMOTER REGIONS OF ZEIN GENES/

Plant chromosomal non-histone high mobility group (HMG) proteins contr ibute substantially to the protein/DNA interactions with A/T-rich DNA regions. Here, we demonstrate the existence of a novel maize 28 kDa HM G-like protein which is rich in basic and acidic amino acid residues a nd which has a high proline content. This HMG-like protein factor was isolated and characterized using 0.35 M NaCl extraction, 2% trichloroa cetic acid (TCA) precipitation and ultracentrifugation. As shown by so uthwestern and band shift experiments, this 28-kDa protein interacts s pecifically with distal A/T-rich elements in the 5' flanking region of the Zcl zein gene. Competition experiments with distamycin A indicate that the protein binds A/T stretches predominantly through minor groo ve contacts. (C) 1998 Elsevier Science Ireland Ltd. All rights reserve d.