Open AccessConformation and Domain Structure of the Non‐histone Chromosomal Proteins, HMG 1 and 2
Author(s) -
CARY Peter D.,
TURNER Christopher H.,
MAYES Elaine,
CRANEROBINSON Colyn
Publication year - 1983
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1983.tb07272.x
Subject(s) - peptide , edman degradation , chemistry , trypsin , acetylation , residue (chemistry) , biochemistry , peptide sequence , histone , non histone protein , stereochemistry , protein structure , enzyme , dna , gene
Proteins HMG 1 and 2 have been digested with trypsin and two major products, stable to further digestion between 8 min and 2 h, have been purified (peptides A and B). Peptide B from HMG 1 has been identified as residues 12–75 and peptide A as residues 94/96–169 by amino acid analyses and Edman degradation. Peptide B spontaneously folds with the formation of 51% helix and exhibits the majority of the perturbed NMR resonances characteristic of folded intact HMG 1. Peptide B is stably folded in the presence of 150 mM NaCl between pH 3 and 10, like intact HMG 1. Peptide A forms 30%α‐helix and also exhibits tertiary folding but is denatured by pH 10. The 11 N‐terminal residues residues removed by trypsin contain both sites of post‐synthetic acetylation (residues 2 and 11), a situation very similar to that found with core histones. It is proposed that HMG 1 and 2 consist of four structural domains, viz: (a) residues 1–11, (b) residues 12 to approximately 75, (c) residues 94–169 and (d) the very acidic region beyond residue 169. The instability of peptide A may mean that it is not a truly independent domain. No structural similarities to histone H1 are therefore observed in HMG 1 and 2.