ISSN:
1573-4927
Keywords:
nuclear acetyltransferase
;
nonhistone substrate
;
high-mobility group acetylase
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Chemistry and Pharmacology
Notes:
Abstract A variety of nonhistone proteins and polyamines has been studied for their substrate activity for nuclear histoneN-acetyltransferase. Nonhistone chromatin high-mobility group (HMG) proteins are found to be as good a substrate for the enzyme as histones. The enzyme also acetylates spermidine and spermine. However, protamine, bovine serum albumin, and ubiquitin are not substrates. Chymotryptic peptides of histone and HMGs retained about 64% of the substrate activity, but trypsin treatment reduced the substrate activity by more than 85%. BothN-acetyltransferase activities for HMGs and histones are copurified through salt extraction, polyethylene glycol fractionation, and chromatography on DEAE-cellulose, phosphocellulose columns, and a HPLC anionic-exchange column. The highly purified nuclear histone acetyltransferase shows similar optimalpH and ping-pong kinetics for both HMGs and histones. TheK m for HMG is 0.25 mg/ml. HMGs are able to accept the acetyl group from isolated acetyl-enzyme intermediate. Denatured gel analysis shows that HMG 1 and HMG 2 are the major proteins acetylated. High salt concentrations, mononucleotides, and DNA, which inhibit histone substrate activity of the enzyme, also inhibit HMG substrate activity. These observations suggest that there is a major nuclearN-acetyltransferase which is responsible for the acetylation of both histones and HMGs and perhaps also of spermine and spermidine. Thus the regulation of the structure and function of chromatin through postsynthetic acetylation can be achieved by a single nuclearN-acetyltransferase.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02399688
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