ISSN:
1365-2958
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
,
Medicine
Notes:
The expression of the chloramphenicol-inducible chloramphenicol-acetyltransferase gene (cat), encoded on Staphylococcus aureus plasmid pUB112, is regulated via a translational attenuation mechanism. Ribosomes, which are arrested by chloramphenicol during synthesis of a short leader peptide, activate catm RNA translation by opening a 5′-located stem-loop structure, thus setting free the cat ribosome-binding site. We have determined the 5′ and 3′ ends of cat mRNA and analysed its stability in Bacillus subtilis. In the absence of the antibiotic, the half-life of cat mRNA is shorter than 0.5 min; it is enhanced to about 8 min by sub-inhibitory concentrations of the drug. No decay intermediates of cat mRNA could be detected, indicating a very fast degradation after an initial rate-limiting step. ochre nonsense mutations in the 5′ region of the cat structural gene, which eliminate cat mRNA translation, did not affect its chloramphenicol-induced stabilization. Mutations in the leader-peptide coding region, which abolish ribosome stalling and, therefore, cat gene induction, also eliminate cat mRNA stabilization. We conclude that cat mRNA is stabilized on induction by a chloram-phenicol-arrested ribosome, which physically protects a nuclease-sensitive target site in the 5′ region of cat mRNA against exo- or endonucleolytic initiation of degradation. This protection is analogous to ermA and ermC mRNA and seems to reflect a general mechanism for stabilization of mRNA derived from inducible antibiotic resistance genes in B. subtilis.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1365-2958.1991.tb01862.x
