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Cloning of the determinants for microcin D93 production and analysis of three different D-type microcin plasmids
1Servicio de Microbiología, Hospital Ramón y Cajal, Madrid, Spain.
Abstract:
Three different microcin plasmids coding for D-type microcins were analyzed. Two of the plasmids (pMccD93 and pCP101) were small, multicopy plasmids and were closely related. The third plasmid (pCP106) was a conjugative, antibiotic multiresistance plasmid. Although plasmids pCP101 and pCP106 were previously classified as A-type microcin plasmids, we have determined that they are, in fact, D type. Furthermore, the determinants for microcin D93 production were cloned from plasmid pMccD93, and a DNA probe for the region implicated in the synthesis of microcin was obtained. This probe hybridized to plasmid C from Escherichia coli strain V517, indicating that this plasmid might be involved in the synthesis of a D-type microcin. The characteristics of replication of plasmid pCP106 were analyzed and appeared to be similar to those of ColEl plasmids, although pCP106 is a conjugative single-copy plasmid.
Insights
Researchers reclassified microcin plasmids, identifying two previously misidentified A-type plasmids as D-type. They also cloned microcin D93 production determinants and found a potential D-type microcin producer in Escherichia coli.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Microcins are ribosomally synthesized peptides with antibiotic properties.
- Plasmids are extrachromosomal DNA elements that can carry genes for microcin production.
- Classification of microcin plasmids is crucial for understanding their genetic basis and spread.
Purpose of the Study:
- To analyze and reclassify three microcin plasmids.
- To identify the genetic determinants for D-type microcin production.
- To investigate the replication characteristics of a conjugative microcin plasmid.
Main Methods:
- Plasmid analysis and characterization.
- Cloning of microcin production determinants.
- DNA hybridization using a specific probe.
- Replication analysis of a conjugative plasmid.
Main Results:
- Two small, multicopy plasmids (pMccD93, pCP101) and one conjugative, multiresistance plasmid (pCP106) were analyzed.
- Plasmids pCP101 and pCP106, previously classified as A-type, were reclassified as D-type microcin plasmids.
- Determinants for microcin D93 production were cloned, and a DNA probe was generated.
- The probe hybridized to a plasmid in Escherichia coli V517, suggesting its involvement in D-type microcin synthesis.
- Plasmid pCP106, a conjugative single-copy plasmid, exhibited replication characteristics similar to ColEl plasmids.
Conclusions:
- The study reclassifies key microcin plasmids, expanding the understanding of D-type microcin diversity.
- Genetic elements responsible for D-type microcin production are identified and characterized.
- A potential new source of D-type microcin in Escherichia coli was discovered.
- The replication mechanism of a conjugative single-copy plasmid was elucidated, offering insights into plasmid biology.
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