The
Escherichia coli gene
ssyB was cloned and sequenced. The
ssyB63 (Cs) mutation is an insertion mutation in
nusB, while the
nusB5 (Cs) mutation suppresses
secY24, indicating that inactivation of
nusB causes cold-sensitive cell growth as well as phenotypic suppression of
secY24. The correct map position of
nusB is 9.5 min rather than I I min as previously assigned. It is located at the distal end of an operon that contains a gene showing significant homology with a
Bacillus subtilis gene involved in riboflavin biosynthesis.
Key words Protein secretion - Suppressor of secY
- Riboflavin biosynthesis -
nusB gene -
ssyB mutation