Translation of the adhE transcript to produce ethanol dehydrogenase requires RNase III cleavage in Escherichia coli.
Previous studies have shown that the adhE gene, which encodes a multifunctional protein with ethanol dehydrogenase activity, is under transcriptional regulation. The level of dehydrogenase activity in cells grown fermentatively is about 10-fold higher than that in cells grown aerobically. In these studies, we mapped the promoter to a region well upstream of the protein-coding region of adhE. Unexpectedly, in mutants lacking the endoribonuclease RNase III, no significant ethanol dehydrogenase activity was detected in cells grown anaerobically on rich (Luria-Bertani) medium supplemented with glucose, even though adhE mRNA levels were high. Indeed, like Delta adhE mutants, strains lacking RNase III failed to grow fermentatively on glucose but grew on the more oxidized carbon source glucuronate. Computer-generated secondary structures of the putative 5' untranslated region of adhE mRNA suggest that the ribosome binding site is occluded by intramolecular base pairing. It seems likely that cleavage of this secondary structure by RNase III is necessary for efficient translation initiation.
Aristarkhov
A
A
Department of Microbiology and Molecular Genetics, Harvard Medical School, Boston, Massachusetts 02115, USA.
Mikulskis
A
A
Belasco
J G
JG
Lin
E C
EC
D000426:Alcohol Dehydrogenase / Q000235:genetics*; D000445:Aldehyde Oxidoreductases / Q000235:genetics*; D000693:Anaerobiosis; D001483:Base Sequence; D004722:Endoribonucleases / Q000378:metabolism; D004790:Enzyme Induction; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D029968:Escherichia coli Proteins; D005285:Fermentation; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000235:genetics*; D009690:Nucleic Acid Conformation; D014176:Protein Biosynthesis; D012323:RNA Processing, Post-Transcriptional; D012329:RNA, Bacterial / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics*; D043244:Ribonuclease III
D029968:Escherichia coli Proteins; D009097:Multienzyme Complexes; D012329:RNA, Bacterial; D012333:RNA, Messenger; D000426:Alcohol Dehydrogenase; C068383:adhE protein, E coli; D000445:Aldehyde Oxidoreductases; D004722:Endoribonucleases; D043244:Ribonuclease III; C468366:ribonuclease III, E coli