The naturally transformable bacterium Haemophilus influenzae Rd contains 14
71 copies of the DNA uptake signal sequence (USS) 5'-AAGTGCGGT in its genom
e. Neisseria meningitidis contains 1891 copies of the USS sequence 5'-GCCGT
CTGAA. The USSs are often found in the base paired stem of transcription te
rminators. (C) 1999 Editions scientifiques et medicales Elsevier SAS.