Histone-induced damage of a mammalian epithelium: the role of protein and membrane structure.
In a previous report [T. J. Kleine, A. Gladfelter, P. N. Lewis, and S. A. Lewis, Am. J. Physiol. 268 (Cell Physiol. 37): C1114-C1125, 1995], we found that the cationic DNA-binding proteins histones H4, H1, and H5 caused a voltage-dependent increase in the transepithelial conductance in rabbit urinary bladder epithelium. In this study, results from lipid bilayer experiments suggest that histones H5-H1 and H4 form variably sized conductive units. Purified fragments of histones H4 and H5 were used to determine the role of histone tertiary structure in inducing conductance. Isolated COOH- and NH2-terminal tails of histone H4, which are random coils, were inactive, whereas the central alpha-helical domain induced a conductance increase. Although the activities of the central fragment and intact histone H4 were in many ways similar, the dose-response relationships suggest that the isolated central domain was much less potent than intact histone H4. This suggests than the NH2- and COOH-terminal tails are also important for histone H4 activity. For histone H5, the isolated globular central domain was inactive. Thus the random-coil NH2- and COOH-terminal tails are important for H5 activity as well. These results indicate that histone molecules interact directly with membrane phospholipids to form a channel and that protein tertiary structure and the degree of positive charge play an important role in this activity.
Kleine
T J
TJ
Department of Physiology and Biophysics, University of Texas Medical Branch, Galveston 77555, USA.
Lewis
P N
PN
Lewis
S A
SA
D000595:Amino Acid Sequence; D000818:Animals; D002645:Chickens; D004268:DNA-Binding Proteins; D004553:Electric Conductivity; D004847:Epithelial Cells / Q000187:drug effects / Q000502:physiology*; D004912:Erythrocytes / Q000378:metabolism; D006657:Histones / Q000737:chemistry / Q000494:pharmacology* / Q000502:physiology*; D066298:In Vitro Techniques; D007700:Kinetics; D008051:Lipid Bilayers; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D008969:Molecular Sequence Data; D018408:Patch-Clamp Techniques; D010446:Peptide Fragments / Q000737:chemistry / Q000494:pharmacology*; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011817:Rabbits; D001743:Urinary Bladder / Q000502:physiology*
D004268:DNA-Binding Proteins; D006657:Histones; D008051:Lipid Bilayers; D010446:Peptide Fragments