>tr|A0A4P6WSW4|A0A4P6WSW4_9ENTR Small ribosomal subunit protein bS21 OS=Citrobacter arsenatis OX=2546350 GN=rpsU PE=3 SV=1 MPVIKVRENEPFDVALRRFKRSCEKAGVLAEVRRREFYEKPTTERKRAKASAVKRHAKKL ARENARRTRLY