Precursor processing during the maturation of a spore-coat protein in Bacillus megaterium KM.

Abstract

A protein of apparent mol.wt. 35000 that is extractable from the purified coat fraction of Bacillus megaterium KM spores is synthesized during sporulation as a precursor protein from which a 12-13 amino acid peptide is removed. Cleavage of this small peptide is delayed until 60-90 min after precursor synthesis and is concomitant with the morphological appearance of stage VI. The addition of chloramphenicol, subsequent to precursor synthesis, prevents the appearance of this late processing event. Two-dimensional non-equilibrium pH-gradient gel electrophoresis of the integument extract of forespores isolated at stage V from sporangia pulse-labelled with L-[35S]methionine 1 h before isolation, revealed both unprocessed and processed components. Similar analysis of total protein from the corresponding mother cells revealed only the unprocessed component in relatively small amounts, suggesting that, although the protein may be synthesized in the mother-cell compartment, processing may be restricted to the forespore. Peptide analysis by limited proteolysis was used to examine the relationship between the 35000- and a 17500-mol.wt. coat protein. The possible implications of limited proteolytic processing to maturation of the spore coat are discussed.

Synthesis and Deposition of Spore Coat Proteins during Sporulation of Bacillus megaterium

“…Aronson and co-workers reported a precursor protein in B. cereus T (1) and stated that there is a common precursor, 60K protein, for many of the mature spore coat proteins in B. subtilis (18). 35K protein in B. megaterium KM as a precursor was reported by Stewart and Ellar (21). We failed to find precursor proteins in this study.…”

Proteolytic processing of a coleopteran-specific δ-endotoxin produced by Bacillus thuringiensis var. tenebrionis

“…The crystals formed were washed with deionized water in order to remove the proteinases. Peptide mapping Peptide mapping by limited proteolysis was performed by a method modified from that of Cleveland et al (1977) as described by Stewart & Ellar (1983). Antiserum preparation and immunoblotting Antibodies were raised to a gel-purified (Walker et al, 1980) 67 kDa polypeptide of B. thuringiensis var.…”

17K‐Spore Coat Protein Antigen in Sporulating Cells of Bacillus megaterium ATCC 19213

“…2). These results suggest that the precursors, if present as reported for other strains (1,3,7,9,11,14), can be very rapidly processed to 17K protein and immediately after processing the protein must be transferred from MCC-Fr to FCP-Fr in sporulating cells. A similar speculation was made in the case of B. megaterium ATCC 12872 from the following data.…”