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At least 73 records · Page 4Linked to original sources
PubMed2026

Effect of Tertiary Lymphoid Structures on Immune Cell Infiltration in the Tumor Microenvironment and Prognosis in Lung Adenocarcinoma.

Tertiary lymphoid structures (TLSs) modulate immune responses in various solid tumors, but their comprehensive role in lung adenocarcinoma (LUAD) remains unclear. In this study, we analyzed RNA-seq data from 539 LUAD patients in The Cancer Genome Atlas (TCGA) and microarray data from 223 samples from the Gene Expression Omnibus (GEO, GSE13213, and GSE37745). TLS signatures were evaluated via unsupervised consensus clustering based on 12 chemokine transcriptome signatures. The relationships between TLS and clinical characteristics, tumor microenvironment (TME) cell infiltration, and prognosis were assessed using ESTIMATE and CIBERSORT. A prognostic model was established using LASSO regression and validated with external datasets. Additionally, H&E and IHC analyses were performed to explore associations between intratumoral TLS density, immune-related molecular expression, and patient prognosis in LUAD. Consensus clustering of the TCGA cohort revealed two distinct LUAD patient clusters according to TLS abundance. Cluster 1 exhibited greater immune cell infiltration, more favorable prognosis, and increased expression of immune checkpoint molecules. We developed a prognostic model comprising eight survival-associated genes that act as independent prognostic factors for patient survival. H&E/IHC analyses revealed that TLS density-regardless of pathological stage-was associated with better prognosis; higher intratumoral TLS density/proportion was also related to more favorable outcomes. IHC confirmed that survival-associated genes (CD5, HLA-DMB, and P2RY13) are independent prognostic indicators in LUAD. Our study demonstrated the close relationship between TLS signatures and an active immune microenvironment, highlighting their potential as independent prognostic indicators in LUAD.

Humans↗
PubMed1992

Sequence, structure, and expression of a wasp venom protein with a negatively charged signal peptide and a novel repeating internal structure.

An expression cDNA library prepared from mRNA from the venom gland of a parasitic wasp, Chelonus sp. near curvimaculatus, was screened with polyclonal antibodies against a 33-kDa venom protein from this wasp. Immunoreactive clones were sequenced, yielding a complete inferred sequence for a protein with an NH2 terminus identical with that of the 33-kDa protein. The structure of the cDNA showed an apparent encoded signal peptide, which was unusual in possessing 2 glutamic acid residues juxtapositioned next to, or replacing, the conventional basic residues. The bulk of the mature protein sequence which follows the NH2-terminal, 5000-kDa hydrophobic domain is composed of a dozen tandem repeats of a highly charged, approximately 14-residue sequence, except for the truncated eighth repeat which terminates in the only proline in this large domain. The primary structure is not closely related to any sequence in the GenBank data bank. Secondary structure analysis identified a turn occurring at or near each of 12 invariantly conserved serine residues. Further, the codon used for this serine was invariant, whereas other serines in the protein (including a nearly invariant serine 2 residues away) used various codons. Results of epitope mapping experiments supported a proposed tertiary structure in which the NH2-terminal 5-kDa forms a hydrophobic core, overlain with the charged repeats. Northern analysis of poly(A) RNA from the venom gland of young adult female wasps showed expression of a single 1-kilobase transcript, for which there is no corresponding message in normal or parasitized host larvae. The remarkable structure of this protein and structural data on other wasp venom proteins suggest an evolutionary pattern in which some proteins critical for venom function evolve by internal tandem duplication, and which are secreted after biosynthesis by a different mechanism from that used for proteins with classical signal peptides containing basic residues.

Amino Acid Sequence↗
PubMed1979

High-resolution phosphorus nuclear magnetic resonance spectra of yeast phenylalanine transfer ribonucleic acid. Melting curves and relaxation effects.

In a continuation of our studies on structural effects on the 31P chemical shifts of nucleic acids, we present 31P NMR spectra of yeast phenylalanine tRNA in the presence and absence of Mg2+. Superconducting field (146 MHz) and 32-MHz 31P NMR spectra reveal approximately 15 nonhelical diester signals spread over approximately 7 ppm besides the downfield terminal 3'-phosphate monoester. In the presence of 10 mM Mg2+, most scattered and main cluster signals do not shift between 22--66 degrees C, thus supporting our earlier hypothesis that 31P chemical shifts are sensitive to phosphate ester torsional and bond angles. At 70 degrees C, all of the signals merge into a single random coil conformation signal. Similar effects are observed in the absence of Mg2+ except that the transition melting temperature is approximately 20 degrees C lower. Measured spin-lattice and spin-spin relaxation times reveal another lower temperature transition besides the thermal denaturation process. A number of the scattered peaks are shifted (0.2--1.7 ppm) and broadened between 22 and 66 degrees C in the presence of Mg2+ as a result of this conformational transition between two intact tertiary structures. The loss of the scattered peaks in the absence of Mg2+ occurs in the temperature range expected for melting of a tertiary structure. An attempt to simulate the 31P spectra of tRNA Phe based upon the X-ray crystallographically determined phosphate ester torsional agles supports the suggestion that the large shifts in the scattered peaks are due to bond angle distortions in the tertiary structure.

Kinetics↗
PubMed1992

Towards identification of cis-acting elements involved in the replication of enterovirus and rhinovirus RNAs: a proposal for the existence of tRNA-like terminal structures.

On the basis of a comparative analysis of published sequences, models for the secondary structure of the 3'-terminal [poly(A)-preceding] untranslated region of the entero- and rhinovirus RNAs were worked out. The models for all these viruses share a common core element, but there are an extra enterovirus-specific element and still an additional element characteristic of a subset of enterovirus RNAs. The two latter models were verified for poliovirus and coxsackievirus B genomes by testing with single-strand and double-strand specific enzymatic and chemical probes. A tRNA-like tertiary structure model for the 3'-terminal folding of enterovirus RNAs was proposed. A similar folding was proposed for the 3' termini of the negative RNA strands as well as for the 5' termini of the positive strand of all entero- and rhinovirus RNAs. Implications of these data for template recognition during negative and positive RNA strands synthesis and for the evolution of the picornavirus genomes are discussed.

Base Sequence↗
PubMed1977

RNA-ligant interactions. (I) Magnesium binding sites in yeast tRNAPhe.

X-ray crystallagraphic studies studies indicate that there are at least four site-specifically bound hydrated Mg2+ ions, [Mg(H2O)n]2+, in yeast tRNAPhe. The size and the octahedral coordination geometry, rather than the charge, of [Mg(H2O)N]2+ appear to be the primary reasons for the specificity of magnesium ions in site-binding and in the stabilization of the tertiary structure of tRNA.

Binding Sites↗
PubMed1975

The binding of complementary oligoribonucleotides to yeast initiator Transfer RNA.

Oligoribonucleotide binding to baker's yeast initiator tRNA was measured by equilibrium dialysis in order to determine which regions of the tRNA were free to bind complementary oligomers and which were involved in secondary and tertiary structure. Association constants of trinucleoside diphosphates and tetranucleoside triphophates complementary to the single-stranded regions of the cloverleaf structure of yeast tRNAfMet were measured at o degrees in 1.0 M NaCl, and 0.01 M MgCl2. The only regions of the tRNA whose complementary oligomers bound to the tRNA were the amino acid acceptor end and the five nucleotides at the 5' end of the anticodon loop. These results differ from those for the other tRNAs studied by this technique; usually oligomers complementary to the dihydrouracil loop bind to the tRNA. The sequence of yeast tRNAfMet and other eucaryotic initiators is unusual. The "TpsiC loop" contains the sequence A-U-C instead of T-psi-C, yet the binding pattern to the THE TpsiC LOOP IS LIKE THAT FOR OTHER TRNAs; no oligomers bind.

Binding Sites↗
PubMed1979

Role of ribothymidine in the thermal stability of transfer RNA as monitored by proton magnetic resonance.

In order to elucidate the functional role of the modified uridines at position 54 of tRNA, the 270 MHz high-field proton NMR spectra of methionine tRNAs from E. coli, from a mutant thereof, and from T. thermophilus, containing ribothymidine, uridine and 2-thioribothymidine, respectively, have been measured as a function of temperature. A comparison of the NMR melting profiles of the minor nucleosides from these tRNAs shows that the melting temperature of uridine containing tRNA is 6 degrees C lower than that of the wild type tRNA whereas that of the 2-thioribothymidine tRNA is 7 degrees C higher than that of the wild type tRNA. These results, therefore, demonstrate that these modifications serve for stabilization of the tertiary structure of tRNA.

Drug Stability↗
PubMed1978

Strong magnesium binding sites in yeast phenylalanine transfer RNA.

To ascertain the sites that are available for strong binding between magnesium ions and phosphate groups in yeast phenylalanine transfer RNA, all distances below 5.5 A separating the phosphoryl oxygens (Op) of the 76 nucleotide residues have been computed from the latest atomic coordinates for the monoclinic form of the tRNA crystallized in the presence of magnesium chloride. The 5.5 A distance is chosen as the upper limit expected for Op....Op distances involved in strong magnesium-phosphate binding, on the basis of studies on a model magnesium phosphodiester hydrate, taking into account the quoted standard deviation in the tRNA atomic coordinates. It is concluded that there are four possible sites for strong magnesium binding in the tRNA molecule, in addition to the three sites previously reported. One of the hypothetical sites: m2G10-OL, U47-OR, could be involved in the first stage of melting of the tRNA molecule, and may be relevant to tertiary structure stabilization, since it links the dihydrouridine arm with the extra (V) loop.

Binding Sites↗
PubMed1976

Structural domains of transfer RNA molecules.

In this article, we have described various detailed features of the conformation of yeast tRNA(Phe) revealed by recent refinement analysis of x-ray diffraction data at 2.5 A resolution. The gross features of the molecule observed in the unrefined version have been largely confirmed and a number of new features found. The unique role of the ribose 2' hydroxyl groups in maintaining a series of nonhelical conformations in this RNA molecule has become apparent. Many of these features are a direct consequence of the geometry of the ribose phosphate backbone of RNA molecules, and these may also be found in structured regions of other RNA species as well. Special attention has been directed toward two conformational motifs revealed by this analysis. These include the striking similarity between the TpsiC and anticodon hairpin turns in the polynucleotide chain, which are stabilized by the participation of uridine in the U turn. In addition, there is frequent occurrence of an arch conformation in the polynucleotide chian which is stabilized by hydrogen bonds from 2' hydroxyl residues to phosphate groups across the base of the arch. The importance of the 2' hydroxyl interactions in defining tertiary structure is illustrated by the fact that, in the nonhelical regions, almost half of the ribose residues are involved in O2' hydrogen-bonding interactions which stabilize the conformation of the molecule.

Anticodon↗
PubMed1976

4-Thiouridine, a built-in probe for structural changes in transfer RNA.

The luminescence of an aqueous solution of 4-thiouridine was compared with its emission when forming part of the polynucleotide chain of tRNA. In both cases excitation into the last absorption band at 335 nm yields a weak emission in the 520--550 nm region. However, while in aqueous solution this emission has a lifetime of approximately 240 ns, it increases in native tRNA to tau congruent to 6.6 mus. Oxygen and Cl- ions quench the thiouridine emission efficiently in aqueous solution while Na+ and Mg2+ ions have no influence on it. On the other hand thiouridine which forms part of a tRNA molecule is quite insensitive to Cl- ions and to O2 while its emission is greatly enhanced by Na+ and Mg2+ ions. From these salt effects as well as from data on the temperature dependence of the emission yield and the decay curve, it is concluded that the site of the thiouridine residue is very well protected within the tertiary structure of tRNA. Both permanent changes in the secondary and in the tertiary structures of the polynucleotide as well as dynamic conformation changes can be observed by following the emission characteristics of its thiouridine residue.

Binding Sites↗
PubMed1978

A study of the thermal unfolding of Escherichia coli phenylalanine transfer RNA by chemical modification at elevated temperatures.

Escherichia coli tRNAPhe was modified by 3 M sodium bisulphite pH 6.0 for 24 h in the temperature range 25 degrees C (x 5 degrees C) to 55 degrees C and in the absence of added magnesium ions. The sites and extents of conversion of cytidines to uridine occurring at each temperature were determined by fingerprinting. The new sites of cytidine modification found at higher reaction temperatures were assumed to arise from breakage of secondary and tertiary structure hydrogen bonds involving cytidine residues. From these data, we conclude that hydrogen bonds within the 'complex core' of the tRNA (including the base pairs G-10 . C-25, C-11 . G-24 and C-13 . G-21 within the dihydrouridine stem and the tertiary structure base pair G-15 . C-48 melt at a lower temperature than the tertiary structure hydrogen bonds between G-19 in the dihydrouridine loop and C-56 in the TpsiC loop.

Base Sequence↗
PubMed1977

1H NMR studies of transfer RNA III: the observed and the computed spectra of the hydrogen-bonded NH resonances of baker's yeast transfer-RNA Phe.

The hydrogen-bonded NH resonances of Baker's yeast tRNAphe in H2O solution with Mg++ have been measured by a 360 MHz spectrometer at 23 degrees C. Totally, fifteen peaks and one shoulder can be resolved which represent 25 +/- 1 protons. Based on the refined atomic coordinates of the tRNAphe in the orthorhombic crystal, on the recent advances in the distance dependence of the ring-current magnetic field effects and on the adopted values for the isolated hydrogen-bonded NH resonances, a computed spectrum consisting of 23 protons was constructed. A quantitative comparison by computer was made between the computed spectrum and the spectrum simulated from the observed spectrum. These two spectra are closely similar but not identical. We suggest that the conformation of yeast tRNAphe in aqueous solution is closely similar but not identical to that found in the crystal, especially in the T psi C region and D region. Also the NH resonances in 3-4 proposed hydrogen bonds (most likely for tertiary structure) may exchange very rapidly in aqueous solution.

Binding Sites↗
PubMed1991

Application of a nuclease from rye nucleus for structural studies of plant ribonucleic acids.

A new nuclease (Rn) isolated from rye nucleus was applied for the structural studies of methionine initiator transfer ribonucleic acid and ribosomal 5S rRNA from yellow lupin seeds. The enzyme shows high specificity for some regions of both RNAs. The dihydrouridine and ribothymidine loops which are supposed to be involved in the tertiary interactions of the methionine initiator tRNA were hydrolysed. The anticodon loop is not digested at all. 5S rRNA was digested in single stranded regions (loops). The cleavage pattern of the tRNA and 5S rRNA obtained with Rn enzyme, suggests not only the high specificity toward single stranded regions, but also some dependence on their tertiary structure.

Base Sequence↗