Mutational analysis of the DNA binding domain A of chromosomal protein HMG1.
We have mutated several residues of the first of the two HMG-boxes of mammalian HMG1. Some mutants cannot be produced in Escherichia coli, suggesting that the peptide fold is grossly disrupted. A few others can be produced efficiently and have normal DNA binding affinity and specificity; however, they are more sensitive towards heating and chaotropic agents than the wild type polypeptide. Significantly, the mutation of the single most conserved residue in the rather diverged HMG-box family falls in this 'in vitro temperature-sensitive' category, rather than in the non-folded category. Finally, two other mutants have reduced DNA binding affinity but unchanged binding specificity. Overall, it appears that whenever the HMG-box can fold, it will interact specifically with kinked DNA.
Falciola
L
L
DIBIT, San Raffaele Scientific Institute, Milan, Italy.
Murchie
A I
AI
Lilley
D M
DM
Bianchi
M
M
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D016384:Consensus Sequence; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics; D006609:High Mobility Group Proteins / Q000737:chemistry* / Q000235:genetics; D008322:Mammals; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013329:Structure-Activity Relationship
D004268:DNA-Binding Proteins; D006609:High Mobility Group Proteins