title: Enhancement of the synthesis of RpoE and StpA by polyamines at the level of translation in escherichia coli under heat shock conditions.
abstract: Proteins whose synthesis is enhanced by polyamines at the level of translation were identified with a polyamine-requiring mutant cultured in the presence of 0.1% glucose and 0.02% glutamate at 42 degrees C. Polyamines had a greater effect on cell growth at 42 degrees C than at 37 degrees C. At 42 degrees C, the synthesis of RpoE (sigma(24)) and StpA, which are involved in the transcription of a number of heat shock response genes, was stimulated by polyamines at the level of translation. In the rpoE and stpA mRNAs, a Shine-Dalgarno (SD) sequence is located at 13 and 12 nucleotides, respectively, upstream of the initiation codon AUG. When the SD sequences were moved to the more common position 7 nucleotides upstream of the initiation codon AUG, the degree of polyamine stimulation was reduced, although the level of RpoE and StpA synthesis was markedly increased. The mechanism underlying polyamine stimulation of RpoE synthesis was then studied. Polyamine stimulation of RpoE synthesis was reduced by changing the bulged-out structure in the initiation site of rpoE mRNA, although the level of RpoE synthesis increased. A selective structural change of this bulged-out region induced by spermidine at 42 degrees C was observed by circular dichroism. Polyamine stimulation of fMet-tRNA binding to ribosomes at 42 degrees C also disappeared by changing the bulged-out structure in the initiation site of rpoE mRNA. The results suggest that polyamines enhance the synthesis of RpoE by changing the bulged-out structure in the initiation site of rpoE mRNA.
authors: Faculty of Pharmacy, Chiba Institute of Science, Choshi, Chiba 288-0025, Japan.
authors: Yusuke
authors: Y
authors: Terui
authors: Kyohei
authors: K
authors: Higashi
authors: Yuzuru
authors: Y
authors: Tabei
authors: Hideyuki
authors: H
authors: Tomitori
authors: Kaneyoshi
authors: K
authors: Yamamoto
authors: Akira
authors: A
authors: Ishihama
authors: Kazuei
authors: K
authors: Igarashi
authors: Keiko
authors: K
authors: Kashiwagi
mesh_terms: D001665:Binding Sites; D002942:Circular Dichroism; D004268:DNA-Binding Proteins / Q000096:biosynthesis*; D004926:Escherichia coli / Q000187:drug effects* / Q000502:physiology / Q000528:radiation effects*; D029968:Escherichia coli Proteins / Q000096:biosynthesis*; D015964:Gene Expression Regulation, Bacterial; D006358:Hot Temperature; D018832:Molecular Chaperones / Q000096:biosynthesis*; D009690:Nucleic Acid Conformation; D011073:Polyamines / Q000378:metabolism*; D014176:Protein Biosynthesis / Q000187:drug effects / Q000528:radiation effects; D012333:RNA, Messenger / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012270:Ribosomes / Q000378:metabolism; D012808:Sigma Factor / Q000096:biosynthesis*; D013312:Stress, Physiological
chemical_list: D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D018832:Molecular Chaperones; D011073:Polyamines; D012333:RNA, Messenger; D012808:Sigma Factor; C090104:StpA protein, E coli; C063202:sporulation-specific sigma factors