Expression of the HIV reverse transcriptase and other essential viral enzymes requires a -1 translational frameshift. The frameshift event is induced by two highly conserved RNA elements within the HIV-1 mRNA: a UUUUUUA heptamer known as the slippery sequence, and a downstream RNA structure. Here, we report structural and thermodynamic evidence that the HIV-1 frameshift site RNA forms a stem-loop and lower helix separated by a three-purine bulge. We have determined the structure of the 45 nucleotide frameshift site RNA using multidimensional heteronuclear nuclear magnetic resonance (NMR) methods. The upper helix is highly thermostable (T(m)>90 degrees C), forming 11 Watson-Crick base-pairs capped by a stable ACAA tetraloop. The eight base-pair lower helix was found to be only moderately stable (T(m)=47 degrees C). A three-purine bulge separates the highly stable upper helix from the lower helix. Base stacking in the bulge forms a wedge, introducing a 60 degrees bend between the helices. Interestingly, this bend is similar to those seen in a number of frameshift inducing pseudoknots for which structures have been solved. The lower helix must denature to allow the ribosome access to the slippery site, but likely functions as a positioning element that enhances frameshift efficiency.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1016/j.jmb.2005.03.038 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Chlamydomonas reinhardtii polysaccharides retard rice starch retrogradation by weakening hydrogen bond strength within starch double helices.
Int J Biol Macromol
January 2025
College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, PR China. Electronic address:
This study investigated the effects of Chlamydomonas reinhardtii polysaccharides (CRPs) on retarding the retrogradation of japonica rice starch (JS) and glutinous rice starch (GS). Structure characterization revealed that CRPs, with an average molecular weight of 505 kDa, mainly consisted of glucose, mannose, and galactose and featured a triple-helix structure. CRPs could reduce the storage modulus increment of JS during the cooling process by interacting with amylose, thereby inhibiting gel network formation.
View Article and Find Full Text PDFTemporally dissociable neural representations of pitch height and chroma.
J Neurosci
January 2025
Department of Psychology, Chinese University of Hong Kong, Hong Kong SAR, China
The extraction and analysis of pitch underpin speech and music recognition, sound segregation, and other auditory tasks. Perceptually, pitch can be represented as a helix composed of two factors: height monotonically aligns with frequency, while chroma cyclically repeats at doubled frequencies. Although the early perceptual and neurophysiological mechanisms for extracting pitch from acoustic signals have been extensively investigated, the equally essential subsequent stages that bridge to high-level auditory cognition remain less well understood.
View Article and Find Full Text PDFThe expression of BHLHE22 in endometrial carcinoma: Associations with mismatch repair protein expression status, tumor-infiltrating immune cells, programmed death-ligand 1 and clinical outcomes.
Taiwan J Obstet Gynecol
January 2025
Department of Pathology, Shuang Ho Hospital, Taipei Medical University, New Taipei City, 23561, Taiwan; Department of Pathology, School of Medicine, College of Medicine, Taipei Medical University, Taipei, 11031, Taiwan. Electronic address:
Objective: Endometrial cancer (EC) shows substantial heterogeneity in their immune microenvironment. BHLHE22 is consistently hypermethylated in EC and high expression of BHLHE22 is likely to be immunosuppressive in the tumor microenvironment. Herein, we evaluated expression of BHLHE22, programmed cell death ligand-1 (PD-L1), CD8, CD68 and mismatch repair proteins in EC.
View Article and Find Full Text PDFCharacterization of dynamic of the structural changes of legume starches during gelatinization.
Int J Biol Macromol
January 2025
Beijing Key Laboratory of Functional Food from Plant Resources, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China. Electronic address:
This study investigated the dynamic changes in legume starches (common vetch, mung bean, and pea) during gelatinization. All three starches displayed a similar pattern: water absorption and swelling at lower temperatures (50-65 °C), structural rupture at medium temperatures (65-75 °C), and melting/reorganization at higher temperatures (75-90 °C). Gelatinization likely starts with internal structural dissociation, as evidenced by the weakening of the double helix structure and decreasing order observed throughout the process.
View Article and Find Full Text PDFHIF-2α/LPCAT1 orchestrates the reprogramming of lipid metabolism in ccRCC by modulating the FBXW7-mediated ubiquitination of ACLY.
Int J Biol Sci
January 2025
Department of Urology, the First Affiliated Hospital of Anhui Medical University, Anhui Medical University, Hefei, Anhui, PR China.
The current research revealed a strong link between lipid reprogramming and dysregulated lipid metabolism to the genesis and development of clear cell renal cell carcinoma (ccRCC). Pathologically, ccRCC exhibits a high concentration of lipid droplets within the cytoplasm. HIF-2α expression has previously been demonstrated to be elevated in ccRCC caused by mutations in the von Hippel-Lindau (VHL) gene, which plays a vital role in the development of renal cell carcinoma.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!