Alterations in the tRNA's of Escherichia coli recovered from lethally infected animals
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Abstract:
Escherichia coli grown in chemically defined iron-deficient media or in fluids containing the iron-binding proteins transferrin, lactoferrin, or ovotransferrin have well-characterized alterations in the chromatographic properties of tRNA's containing the modified nucleoside 2-methylthio-N6-(delta2-isopentenyl)-adenosine. The present work shows that similar tRNA alterations occur in E. coli O111 recovered from the peritoneal cavities of lethally infected guinea pigs and rabbits. Adding iron to these in vivo-grown bacteria resulted in the rapid conversion of chromatographically abnormal tRNA's to the normal species. The work strongly suggests that host iron-binding proteins, present in mucosal and other secretions, can affect the metabolism of invading organisms. The idea that the tRNA alterations are connected with the adaptation of E. coli to growth under the iron restricted conditions imposed by iron-binding proteins in tissue fluids, and thus with bacterial pathogenicity, is therefore made particularly attractive.
Insights
Host iron-binding proteins alter bacterial transfer RNA (tRNA) metabolism, impacting pathogenicity. Restoring iron levels normalizes tRNA, suggesting a key adaptation mechanism for invading bacteria like Escherichia coli.
Area of Science:
- Microbiology
- Molecular Biology
- Biochemistry
Background:
- Escherichia coli tRNA exhibits altered chromatographic properties when grown in iron-deficient media or with iron-binding proteins.
- These alterations involve the modified nucleoside 2-methylthio-N6-(delta2-isopentenyl)-adenosine.
Purpose of the Study:
- To investigate if similar tRNA alterations occur in E. coli during in vivo infections.
- To determine the effect of iron availability on these tRNA changes in vivo.
- To explore the link between tRNA alterations, iron restriction, and bacterial pathogenicity.
Main Methods:
- Culturing E. coli in iron-deficient and iron-binding protein-containing media.
- Analyzing E. coli O111 recovered from infected guinea pigs and rabbits.
- Chromatographic analysis of tRNA.
- Supplementing in vivo-grown bacteria with iron.
Main Results:
- E. coli O111 recovered from infected animals showed similar tRNA alterations as those grown in vitro under iron-restricted conditions.
- Addition of iron to in vivo-grown bacteria rapidly normalized the abnormal tRNA species.
- Host iron-binding proteins significantly affect bacterial tRNA metabolism.
Conclusions:
- Host iron-binding proteins in tissue fluids can influence the metabolism of invading bacteria.
- tRNA alterations are likely an adaptive response of E. coli to iron-restricted environments.
- These adaptations may play a crucial role in bacterial pathogenicity.