Alterations in the tRNA's of Escherichia coli recovered from lethally infected animals.

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.