How do bacterial ribosome binding sites work?

The bacterial ribosome binds to specific sequences on an mRNA, primarily the ribosome binding site and the start codon (AUG). The 16S rRNA of the bacterial ribosome are formed when the RBS base-pairs with RNA. The start condon base pairs with the initiator tRNA, which is bound to the ribosome. In order to allow contact between the appropriate parts of the ribosome complex and the two mRNA sequences, the sequences must be positioned approximately six to seven nucleotides apart.