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Proteins whose synthesis is enhanced by polyamines at the level of translation were identified with a polyaminerequiring 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.sup.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.

A spermidine excretion protein in Escherichia coli was looked for among 33 putative drug exporters thus far identified. Cell toxicity and inhibition of growth due to overaccumulation of spermidine were examined in an E. coli strain deficient in spermidine acetyltransferase, an enzyme that metabolizes spermidine. Toxicity and inhibition of cell growth by spermidine were recovered in cells transformed with pUCmdtJI or pMWmdtJI, encoding MdtJ and MdtI, which belong to the small multidrug resistance family of drug exporters. Both mdtJ and mdtI are necessary for recovery from the toxicity of overaccumulated spermidine. It was also found that the level ofmdtJI mRNA was increased by spermidine. The spermidine content in cells cultured in the presence of 2 mM spermidine was decreased, and excretion of spermidine from cells was enhanced by MdtJI, indicating that the MdtJI complex can catalyze excretion of spermidine from cells. It was found that [Tyr.sup.4], [Trp.sup.5], [Glu.sup.15], [Tyr.sup.45], [Tyr.sup.61], and [Glu.sup.82] in MdtJ and [Glu.sup.5], [Glu.sup.19], [Asp.sup.68], [Trp.sup.68], and [Trp.sup.81] in MdtI are involved in the excretion activity of MdtJI.

Proteins whose synthesis is enhanced by polyamines at the level of translation were identified in a polyaminerequiring mutant cultured in the presence of 0.1% glucose and 0.02% glutamate instead of 0.4% glucose as an energy source. Under these conditions, enhancement of cell growth by polyamines was almost the same as that in the presence of 0.4% glucose. It was found that synthesis of RpoN, Cra, and H-NS was enhanced by polyamines at the level of translation at the early logarithmic phase of growth ([A.sub.540] of 0.15). The effects of polyamines on synthesis of RpoN, H-NS, and Cra were due to the existence of unusual Shine-Dalgarno sequences (RpoN and H-NS) and an inefficient GUG initiation codon (Cra) in their mRNAs. Thus, rpoN, cra and hns genes were identified as new members of the polyamine modulon. Because most of the polyamine modulon genes thus far identified encode transcription factors (RpoS [[[sigma].sup.38]], Cya, FecI [[[sigma].sup.18]], Fis, RpoN [[[sigma].sup.54]], Cra, and H-NS), DNA microarray analysis of mRNA expressed in cells was performed. At the early logarithmic phase of growth, a total of 97 species of mRNAs that were up-regulated by polyamines more than twofold were under the control of seven polyamine modulon genes mentioned above.

The fourth author's name is spelled incorrectly. The correct name is: Kyohei Higashi. The correct citation is: Mencio CP, Tilve SM, Suzuki M, Higashi K, Katagiri Y, Geller HM (2022) A novel cytoskeletal action of xylosides. PLOS ONE 17(6): e0269972. https://doi.org/10.1371/journal.pone.0269972.By Caitlin P. Mencio; Sharada M. Tilve; Masato Suzuki; Kyohei Higashi; Yasuhiro Katagiri and Herbert M. GellerReported by Author; Author; Author; Author; Author; Author [Extracted from the article]

Adipocytes, which comprise the majority of white adipose tissue (WAT), are involved in obesity‐related pathology via various mechanisms, including disturbed lysosomal enzymatic activity and accumulation of oxidative stress. Sequestosome 1 (SQSTM1/p62) is an autophagy marker that participates in antioxidative responses via the activation of nuclear factor erythroid‐derived 2‐like 2 (NRF2). Trehalose is a non‐reducing disaccharide reported to suppress adipocyte hypertrophy in obese mice and improve glucose tolerance in humans. We recently revealed that trehalose increases SQSTM1 levels and enhances antioxidative capacity in hepatocytes. Here, to further evaluate the mechanism behind the beneficial effects of trehalose on metabolism, we examined SQSTM1 levels, autophagy, and oxidative stress in trehalose‐treated adipocytes. We initially confirmed that trehalose increases SQSTM1 transcription and protein levels without affecting autophagy in adipocytes. Trehalose also elevated transcription of several lysosomal genes and the activity of cathepsin L, a lysosomal enzyme, independently of the transcription factor EB. In agreement with our data from hepatocytes, trehalose induced the nuclear translocation of NRF2 and the transcription of its downstream antioxidative genes, resulting in reduced cellular reactive oxygen species levels. Moreover, some cellular trehalose was detected in trehalose‐treated adipocytes, implying that extracellular trehalose is taken into cells. These observations reveal the mechanism behind the beneficial effects of trehalose on metabolism and suggest its potential for preventing or treating obesity‐related pathology. [ABSTRACT FROM AUTHOR]