The molecular basis of histidase induction in Bacillus subtilis

Leland H. Hartwell, Boris Magasanik

Research output: Contribution to journalArticlepeer-review

30 Scopus citations


Bacillus subtilis can be induced by l-histidine at 37°C in medium containing glutamate as source of carbon to form an enzyme, histidase, that converts l-histidine to urocanic acid. This enzyme was highly purified and characterized and appears in the cell 5 minutes following the addition of the inducer. Actinomycin D, an inhibitor of RNA synthesis, and chloramphenicol, an inhibitor of protein synthesis, were used to elucidate the induction process. The capacity for histidase biosynthesis appears 2 min after the addition of the inducer. This capacity decays exponentially with a half-life of 2·4 min and its synthesis is inhibited by actinomycin D; the compound that endows the cell with the capacity to synthesize histidase is apparently a messenger RNA specific for this enzyme; the product of this messenger RNA is a precursor of histidase, an enzymically inactive protein whose rate of synthesis is proportional to the intracellular level of the specific messenger RNA. This precursor is converted with an initial delay of approximately 2 min to the active enzyme by a process which does not involve the synthesis of peptide bonds. When, approximately 9 min after addition of the inducer, the steady state of enzyme synthesis has been reached, each cell contains sufficient precursor to form approximately 100 molecules of histidase, and produces approximately 50 molecules of the enzyme per min ; the cell produces and loses every minute the capacity to make approximately 15 molecules of histidase per min. A fully induced cell contains approximately 15,000 molecules of histidase.

Original languageEnglish (US)
Pages (from-to)401-420
Number of pages20
JournalJournal of molecular biology
Issue number4
StatePublished - Jan 1 1963
Externally publishedYes

ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology


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