Nonhistone chromosomal proteins and histone gene transcription

Auxin-induced changes in chromosomal protein phosphorylation in wounded potato tuber parenchyma

White potato tuber tissue reacts upon wounding with a rapid increase in activity of both chromatin-bound DNA-dependent RNA polymerase I and II as well as protein phosphokinase. This enhancement is more pronounced if 0.1 mM of the synthetic auxin 2,4-dichlorophenoxyacetic acid (2,4-D) is added shortly after wounding. The effect of the hormone on protein kinases becomes evident only after a lag phase of about 10h and lasts throughout the wound-healing period. Different protein kinases with different substrate specificity (i.e. histone, phosvitin, casein phosphokinases) are distinctly more active in auxin-treated tissues. The phosphate is apparently introduced into proteins via seryl and threonyl bonds. Acyl or histidyl phosphates are not involved.The properties of protein phosphokinases are virtually identical in wounded and auxin-treated tissues. However, the pattern of chromosomal proteins and the pattern of their phosphorylation in hormone-treated tissues is different from those in wounded ones. A drastic stimulation of phosphorylation of both high and low-molecular weight chromosomal proteins is characteristic for auxin-treated cells.