Non-histone chromosomal protein HMG1 reduces the histone H5-induced changes in c.d. spectra of DNA: the acidic C-terminus of HMG1 is necessary for binding to H5.
Chemical cross-linking was used to study the interaction between non-histone high-mobility-group (HMG)1 and histone H5 in free solution. The presence of acidic C-terminal domain in HMG1 was shown to be a prerequisite for HMG1 binding to histone H5. The objective of this communication is to ascertain whether HMG1 could affect the conformation of DNA associated with a linker histone H5. Complexes of histone H5 with chicken erythrocyte DNA or an alternating purine-pyrimidine polynucleotide poly[d(A-T)] were prepared at different molar ratios H5/DNA. Changes in DNA conformation in the complexes with histone H5 or H5/HMG1 were monitored by circular dichroism (c.d.). Depending on the molar ratio H5/poly[d(A-T)], under conditions limiting the complex aggregation, three distinct types of c.d. spectra were observed. The addition of HMG1 to H5-DNA complexes reduced in all cases the histone H5-induced conformational changes in poly[d(A-T)]. The sensitivity of H5-poly[d(A-T)] complexes to HMG1 was inversely proportional to the amount of H5 in the complex. The effect of HMG1 was not observed upon removal of the acidic C-terminal domain of HMG1.
Stros
M
M
Institute of Biophysics, Czechoslovak Academy of Sciences, Brno.
Vorlícková
M
M
D000818:Animals; D002417:Cattle; D002645:Chickens; D002942:Circular Dichroism; D003432:Cross-Linking Reagents; D004247:DNA / Q000737:chemistry*; D006609:High Mobility Group Proteins / Q000737:chemistry*; D006657:Histones / Q000737:chemistry*; D009690:Nucleic Acid Conformation
D003432:Cross-Linking Reagents; D006609:High Mobility Group Proteins; D006657:Histones; D004247:DNA