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Major proteins released by a protein-producing bacterium, Bacillus brevis 47, are derived from cell wall protein
Abstract:
B. brevis 47 secretes a vast amount of protein consisting mainly of two kinds with approximate molecular weights of 130,000 and 150,000. The two major extracellular proteins were indistinguishable from those of cell wall protein by SDS-polyacrylamide gel electrophoresis. Based on the results of analysis of amino acid composition, limited proteolysis followed by electrophoresis, and the cross-reactivity of antisera, we conclude that the 130K and 150K extracellular proteins are derived from the respective cell wall proteins. Furthermore, the NH2-terminal amino acid analysis suggests that the two major extracellular proteins are released from the cell wall without any modification of the NH2-terminal portion.
Insights
Bacillus brevis 47 secretes major extracellular proteins (130K and 150K) originating from its cell wall. These proteins are released without modification to their amino-terminal sequences.
Area of Science:
- Microbiology
- Protein Biochemistry
Background:
- Bacillus brevis 47 is known to secrete significant quantities of extracellular proteins.
- Understanding the origin and nature of these secreted proteins is crucial for characterizing bacterial physiology and potential applications.
Purpose of the Study:
- To identify and characterize the major extracellular proteins secreted by Bacillus brevis 47.
- To determine the relationship between the extracellular proteins and the bacterial cell wall components.
Main Methods:
- Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) to assess molecular weights and purity.
- Amino acid composition analysis to compare protein structures.
- Limited proteolysis followed by electrophoresis to analyze protein fragments.
- Antisera cross-reactivity tests to assess protein homology.
- NH2-terminal amino acid sequencing to detect modifications.
Main Results:
- Two major extracellular proteins with molecular weights of approximately 130,000 (130K) and 150,000 (150K) were identified.
- These extracellular proteins were indistinguishable from cell wall proteins via SDS-PAGE.
- Analysis of amino acid composition, proteolytic digestion patterns, and antibody cross-reactivity indicated that the extracellular proteins are derived from cell wall proteins.
- NH2-terminal sequencing revealed no modification of the amino-terminal portion during release.
Conclusions:
- The major extracellular proteins secreted by Bacillus brevis 47 are derived from its cell wall.
- The release mechanism involves the shedding of cell wall proteins without N-terminal modification.