期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 107, 期 14, 页码 6258-6263出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.1001062107
关键词
bacterial competition; bacterial growth inhibition; growth regulation; Paenibacillus dendritiformis; subtilisin
资金
- Welch Foundation [F-1573]
- National Institutes of Health [AI50669]
- National Science Foundation-sponsored Center for Theoretical Biological Physics [PHY-0216576, 0225630]
- University of California at San Diego
- Sid W. Richardson Foundation
- Division Of Physics
- Direct For Mathematical & Physical Scien [0225630] Funding Source: National Science Foundation
Sibling Paenibacillus dendritiformis bacterial colonies grown on low-nutrient agar medium mutually inhibit growth through secretion of a lethal factor. Analysis of secretions reveals the presence of subtilisin (a protease) and a 12 kDa protein, termed sibling lethal factor (Slf). Purified subtilisin promotes the growth and expansion of P. dendritiformis colonies, whereas Slf is lethal and lyses P. dendritiformis cells in culture. Slf is encoded by a gene belonging to a large family of bacterial genes of unknown function, and the gene is predicted to encode a protein of approximately 20 kDa, termed dendritiformis sibling bacteriocin. The 20 kDa recombinant protein was produced and found to be inactive, but exposure to subtilisin resulted in cleavage to the active, 12 kDa form. The experimental results, combined with mathematical modeling, show that subtilisin serves to regulate growth of the colony. Below a threshold concentration, subtilisin promotes colony growth and expansion. However, once it exceeds a threshold, as occurs at the interface between competing colonies, Slf is then secreted into the medium to rapidly reduce cell density by lysis of the bacterial cells. The presence of genes encoding homologs of dendritiformis sibling bacteriocin in other bacterial species suggests that this mechanism for self-regulation of colony growth might not be limited to P. dendritiformis.
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