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The amino acid sequence specificity of a protease from spores of Bacillus megaterium.

1980; Elsevier BV; Volume: 255; Issue: 8 Linguagem: Inglês

10.1016/s0021-9258(19)85749-6

1083-351X

Peter Setlow, Craig Gérard, Juris Ozols,

Machine Learning in Bioinformatics

Previous work has shown that the degradation of 20% of total protein which occurs early in germination of Bacillus megaterium spores is initiated by an endoprotease.This enzyme is found only in the spore and is active only on the spore proteins degraded during germination.Action of the spore protease in vitro on the three major proteins (Proteins A, B, and C) which are degraded in vivo during germination results in cleavage of one (A and C protein) or two (B protein) peptide bonds.The sequences surrounding the cleavage sites are -Tyr-Glui Ile-Ala-Ser-Glu-Phe-in the A protein, -Phe-Glui Ile-Ala-Ser-Glu-Phe-in the C protein, and -Thr-Glui Phe-Gly-Ser-Glu-Thr-, and -Thr-Glui Phe-Ala-Ser-Glu-Thr-in the B protein, with cleavage taking place at the glutamyl bond noted by the arrow.The similarity of these four sequences suggests the possibility that the specificity of the spore protease may be due to its requirement for a specific pentapeptide sequence of the type -R-Glu-(Phe or 1le)-(Gly or Ala)-Ser-Glu-R-for recognition and cleavage.However, it is also possible that it is the conformation of the A, B, and C proteins which determines their site of cleavage by the spore protease.Approximately 20% of the total protein of dormant spores of Bacillus and Clostridium species is degraded to amino acids in the fist minutes of spore germination (1-3).Three proteins, termed A, B and C, account for -85% of the protein degraded during germination of Bacillus megaterium spores (1).These proteins are unique to the spore stage of growth, and all have low molecular weights (7000 to 9000) (2).The primary structure of Protein A has been reported (4).Similar proteins are present in spores of other species (1, 3).A major function of these proteins is to be degraded during germination, thus supplying amino acids for protein synthesis during spore germination and outgrowth (5).Other functions for these proteins, such as involvement in the resistance of spores to ultraviolet light, have been proposed but not yet proven (2, 6).The degradation of the A, B, and C proteins during germination of B. megaterium spores is initiated by an endoprotease, also found only in the spore (7, 8).During spore germination this enzyme cleaves the A, B, and C proteins into a few large oligopeptides which are then degraded to free amino