Comparison of Bacteroides thetaiotaomicron and Escherichia coli 16S rRNA gene expression signals

Abstract

There are barriers to cross-expression of genes betweenBacteroidesspp. andEscherichia coli. In this study, alux-based reporter system was developed forBacteroidesand used to compare the promoter structure and function of aBacteroides thetaiotaomicron4001 (BT4001) 16S rRNA promoter with those ofE. coli in vivo. Analysis of the BT4001 sequences upstream of the 16S rRNA gene revealed the same overall structure known forE. coli16S rRNA promoters in that there were two promoters separated by ∼150 bp. However, the BT4001 16S rRNA promoter contains the proposedBacteroides−7 and −33 consensus sequences instead of theE. coli−10 and −35 consensus sequences. The biological activity of various configurations of the BT4001 16S rRNA promoter was analysed. Experiments pairing the BT4001 16S rRNA promoter with anE. coliRBS, and vice-versa, confirmed that gene expression between the two species is restricted at the level of transcription. InBacteroides, a difference in translation initiation also appears to limit expression of foreign genes.