Bacteroidia ribosomes are "blind" to Shine-Dalgarno (SD) sequences because the anti-SD (ASD) of 16S rRNA is sequestered by bS21, bS18, and bS6 on the 30S platform. In Flavobacterium johnsoniae, one gene contains a strong SD sequence-rpsU, which encodes bS21. Flavobacterium johnsoniae ribosomes lacking bS21 translate rpsU at a higher rate, which establishes an autoregulatory cycle. Here, we targeted the ASD of 16S rRNA in F. johnsoniae, ablating the core element (CCUCC to GAAGC). Replacement of e