J. Biol. Chem., Vol. 255, Issue 18, 8417-8423, Sep, 1980
In vivo and in vitro synthesis of the spore-specific proteins A and C of bacillus megaterium
SS Dignam and P Setlow
Pulse labeling of cells of Bacillus megaterium followed by cell disruption
and immunoprecipitation has shown that the spore-specific Proteins A and C
are synthetized only during a discrete time period in sporulation. At its
maximum, the synthesis of the A- and C-proteins accounted for 5% of the
protein being synthesized in vivo, but the mRNA for the A- and C-proteins
had a lifetime no longer than that of other mRNAs translated at that time.
No evidence was found for synthesis of Proteins A or C in high molecular
weight precursor form, and essentially all of the newly synthesized A- and
C-protein was found in the forespore. Isolation of total RNA from cells in
various stages of growth and sporulation, translation of this RNA in a
cell-free system from vegetative cells, and immunoprecipitation showed that
the ability of cellular RNA to promote A- and C-protein synthesis in vitro
was directly proportional to the rate at which the cells had been
synthesizing Proteins A and C in vivo. These data indicate that synthesis
of Proteins A and C during sporulation in B. megaterium is primarily under
transcriptional control. The identity of the immunoprecipitated labeled
material material synthesized in vitro with the A- and C-proteins was
established by: 1) their co-migration on sodium dodecyl
sulfate-polyacrylamide gels; 2) co-migration on high performance liquid
chromatography of tryptic peptides from an [35S]methionine-labeled
immunoprecipitate with the methionine- containing tryptic peptides of the
A- and C-proteins; and 3) digestion of the labeled immunoprecipitate with a
protease specific for the A- and C-proteins.
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