PLANT PHYSIOLOGY , Vol 109, Issue 2 393-407, Copyright © 1995 by American Society of Plant Biologists
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GENE REGULATION AND MOLECULAR GENETICS |
Histones of Chlamydomonas reinhardtii (Synthesis, Acetylation, and Methylation)
J. H. Waterborg, A. J. Robertson, D. L. Tatar, C. M. Borza and J. R. Davie
School of Biological Sciences, University of Missouri-Kansas City, 5100 Rockhill Road, Kansas City,Missouri 64110-2499 (J.H.W., A.J.R., D.L.T., C.M.B.)
Histones of the green alga Chlamydomonas reinhardtii were prepared by a new
method and fractionated by reversed-phase high-performance liquid
chromatography. Acid-urea-Triton gel analysis and tritiated acetate
labeling demonstrated high levels of steady-state acetylation for the
single histone H3 protein, in contrast to low levels on histones H4 and
H2B. Twenty percent of histone H3 is subject to dynamic acetylation with,
on average, three acetylated lysine residues per protein molecule. Histone
synthesis in light-dark-synchronized cultures was biphasic with pattern
differences between two histone H1 variants, between two H2A variants, and
between H2B and ubiquitinated H2B. Automated protein sequence analysis of
histone H3 demonstrated a site-specific pattern of steady-state acetylation
between 7 and 17% at five of the six amino-terminal lysines and of
monomethylation between 5 and 81% at five of the eight amino-terminal
lysines in a pattern that may limit dynamic acetylation. An algal histone
H3 sequence was confirmed by protein sequencing with a single threonine as
residue 28 instead of the serine28-alanine29 sequence, present in all other
known plant and animal H3 histones.
