Although some experiments suggest that the ribosome displays specificity for the identity of the esterified amino acid of its aminoacyl-tRNA substrate, a study measuring dissociation rates of several misacylated tRNAs containing the GAC anticodon from the A site showed little indication for such specificity. In this article, an expanded set of misacylated tRNAs and two 2'-deoxynucleotide-substituted mRNAs are used to demonstrate the presence of a lower threshold in k(off) values for aa-tRNA binding to the A site. When a tRNA binds sufficiently well to reach this threshold, additional stabilizing effects due to the esterified amino acid or changes in tRNA sequence are not observed. However, specificity for different amino acid side chains and the tRNA body is observed when tRNA binding is sufficiently weaker than this threshold. We propose that uniform aa-tRNA binding to the A site may be a consequence of a conformational change in the ribosome, induced by the presence of the appropriate combination of contributions from the anticodon, amino acid and tRNA body.
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http://dx.doi.org/10.1093/nar/gkn1040 | DOI Listing |
Sci Rep
December 2024
Department of Life Sciences, Pohang University of Science and Technology, Pohang, 37673, Kyungbook, Republic of Korea.
Alanine racemase (Alr) catalyzes the pyridoxal 5'-phosphate (PLP)-dependent racemization between L- and D-alanine in bacteria. Owing to the potential interest in targeting Alr for antibacterial drug development, several studies have determined the structures of Alr from different species, proposing models for the reaction mechanism. Insights into its reaction dynamics may be conducive to a better understanding of the Alr reaction mechanism.
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December 2024
Department of Endocrinology, Children's Hospital, Zhejiang University School of Medicine, National Children's Regional Medical Center, National Clinical Research Center for Child Health, 3333 Binsheng Road, Hangzhou, 310052, Zhejiang Province, China.
Williams Syndrome (WS) is a rare neurodevelopmental disorder with a prevalence of 1 in 7500 to 1 in 20,000 individuals, caused by a microdeletion in chromosome 7q11.23. Despite its distinctive clinical features, the underlying metabolic alterations remain largely unexplored.
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December 2024
Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Falmouth, USA.
Coral reef sponges efficiently take up particulate and dissolved organic matter (DOM) from the water column and release compounds such as nucleosides, amino acids, and other dissolved metabolites to the surrounding reef via their exhalent seawater, but the influence of this process on reef picoplankton and nutrient processing is relatively unexplored. Here we examined the impact of sponge exhalent on the reef picoplankon community and subsequent alterations to the reef dissolved metabolite pool. We exposed reef picoplankton communities to a sponge exhalent water mixture (Niphates digitalis and Xestospongia muta) or filtered reef seawater (control) in closed, container-based dark incubations.
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December 2024
Microelement Research Center, College of Resources and Environment, Huazhong Agricultural University, No. 1 Shizishan Road, Wuhan, 430070, China.
The quality of cigar tobacco leaves is profoundly affected by the timing of their harvest, with both early and late collections resulting in inferior characteristics. While the relationship between maturity and physiological metabolic processes is acknowledged, a comprehensive understanding of the physiological behavior of cigar leaves harvested at different stages remains elusive. This research investigated the physiological and metabolomic profiles of the cigar tobacco variety CX-014, grown in Danjiangkou City, Hubei Province, with leaves sampled at 35 (T1), 42 (T2), 49 (T3), and 56 (T4) days post-inflorescence removal.
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December 2024
Institute of Agriculture and Life Science, Gyeongsang National University, Jinju, 52828, Republic of Korea.
Heat stress (HS) is an impactful condition in ruminants that negatively affects their physiological and rumen microbial composition. However, a fundamental understanding of metabolomic and metataxonomic mechanisms in goats under HS conditions is lacking. Here, we analyzed the rumen metabolomics, metataxonomics, and serum metabolomics of goats (n = 10, body weight: 41.
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