Processing Of Precursor Research Articles

Mitochondrial mRNA and the Small Subunit rRNA in Budding Yeasts Undergo 3'-End Processing at Conserved Species-specific Elements.

Respiration in eukaryotes depends on mitochondrial protein synthesis, which is performed by organelle-specific ribosomes translating organelle-encoded mRNAs. Although RNA maturation and stability are central events controlling mitochondrial gene expression, many of the molecular details in this pathway remain elusive. These include cis- and trans-regulatory factors that generate and protect the 3' ends. Here, we mapped the 3' ends of mitochondrial mRNAs of yeasts classified into multiple families of the subphylum Saccharomycotina. We found that the processing of mitochondrial 15S rRNA and mRNAs involves species-specific sequence elements, which we term 3'-end RNA processing elements (3'-RPEs). In Saccharomyces cerevisiae, the 3'-RPE has long been recognized as a conserved dodecamer sequence, which recent studies have shown to specifically interact with the nuclear genome-encoded pentatricopeptide repeat protein Rmd9. We also demonstrate that, analogous to Rmd9 in Saccharomyces cerevisiae, two Rmd9 orthologs from the Debaryomycetaceae family interact with their respective 3'-RPEs found in mRNAs and 15S rRNA. Thus, Rmd9-dependent processing of mitochondrial RNA precursors is a common mechanism among the families of the Saccharomycotina subphylum. This represents an example of mitochondrial-nuclear co-evolution. Surprisingly, we observed that 3'-RPEs often occur upstream of stop codons in complex I subunit mRNAs from yeasts of the CUG-Ser1 clade. We examined two of these mature mRNAs and found that their stop codons are indeed removed. Thus, translation of these transcripts would require a novel termination mechanism. Our findings establish Rmd9 as a key evolutionarily conserved factor in both mitochondrial mRNA metabolism and mitoribosome biogenesis in a variety of yeasts.

Chemically Processed Porous V2O5 Thin‐Film Cathodes for High‐Performance Thin‐film Zn‐Ion Batteries

AbstractThin‐film rechargeable batteries have a wide range of applications due to their unique properties such as small size, thinness, and the ability to power smart devices, including portable electronic devices, medical devices, smart cards, RFID tags, and Internet of Things (IoT) devices. Processing thin‐film electrodes for these batteries generally relies on standard physical vapor deposition technologies. However, producing porous thin‐films using these techniques presents significant challenges. Here, a rapid and cost‐effective chemical route for processing porous vanadium oxide (V2O5) thin‐film cathodes for application in Zinc‐ion‐based thin‐film batteries (Zn‐TFBs) is explored. The V2O5 precursor process uses an industrially viable spraying technique, which not only offers impressive charge storage performance of an areal capacity of 47.34 µAh cm−2, areal energy of 50.18 µWh cm−2, and areal power of 53 µW cm−2 at 50 µA cm−2 in the optimized gel‐electrolyte composition. This study introduces a cost‐effective and industrially viable method for processing highly porous thin‐film cathodes, enabling the production of high‐performance, affordable, and safer thin‐film batteries.

Exploring phytochemical inhibitors of protein kinase C alpha for therapeutic targeting of Alzheimer's disease.

Alzheimer's disease (AD) is characterized by neurodegeneration linked to amyloid-β (Aβ) plaques and tau protein tangles. Protein kinase C alpha (PKCα) plays a crucial role in modulating amyloid-β protein precursor (AβPP) processing, potentially mitigating AD progression. Consequently, PKCα stands out as a promising target for AD therapy. Despite the identification of numerous inhibitors, the pursuit of more effective and precisely targeted PKCα inhibitors remains crucial. In this study, we employed an integrated virtual screening approach of molecular docking and molecular dynamics (MD) simulations to identify phytochemical inhibitors of PKCα from the IMPPAT database. Molecular docking screening via InstaDock identified compounds with strong binding affinities to PKCα. Subsequent ADMET and PASS analyses filtered out compounds with favorable pharmacokinetic profiles. Interaction analysis using Discovery Studio Visualizer and PyMOL further elucidated binding conformations of selected compounds with PKCα. Top hits underwent 200 ns MD simulations using GROMACS to validate stability of the interactions. Finally, we propose two phytochemicals, Kammogenin and Imperialine, with appreciable drug-likeliness and binding potential with PKCα. Taken together, the findings suggest Kammogenin and Imperialine as potential PKCα inhibitors, highlighting their therapeutic promise for AD after further validation.

Carbon Dot Synthesis and Purification: Trends, Challenges and Recommendations

AbstractCarbon dots (CDs) have rapidly emerged as a new family of carbon‐based nanomaterials since their initial discovery two decades ago. Numerous appealing properties, such as precursor and synthesis process flexibility, tunable photoluminescence, and good biocompatibility, have enabled their widespread applications in sensing, catalysis, energy, and biomedical fields. As the field expands, notable efforts have recently focused on mechanistically elucidating the structural formation and optical behavior of CDs. However, the absence of “clean” CDs presents a major obstacle to achieving a solid understanding of these aspects. Often, the claimed CDs are, in fact, a mixture of small molecules, oligomers, nano‐sized aggregates, or even microparticles. Such coexistence of impurities markedly impacts the physicochemical properties of resulting CD‐based mixtures, hampering the resolution of key mechanistic questions. Here, we aim to address this fundamental shortcoming of the field, going beyond the customary focus of the existing reviews that predominantly cover synthesis, optical performance, and application prospects. We begin with an overview of CD synthesis and then thoroughly examine the purification methods, including filtration, dialysis, electrophoresis, and chromatography. The insights provided here will guide the researchers towards obtaining high‐quality CDs, employing proper combinations of available tools, and ultimately paving the way for more demanding applications.

Ablation of PC1/3 in POMC-Expressing Tissues but Not in Immune Cells Induces Sepsis Hypersensitivity.

Prohormone convertase 1/3 (PC1/3) is an endopeptidase required for the processing of neuropeptide and endocrine peptide precursors; it is expressed in neuroendocrine tissues as well as in immune cells. In response to endotoxemia, global PC1/3 knockout mice mount a cytokine storm and die rapidly. Further, immune cells isolated from these mice have a pro-inflammatory signature, suggesting that PC1/3 activates an unknown anti-inflammatory peptide precursor in immune cells. Here, we tested this hypothesis using tissue-specific PC1/3 ablation models. Knocking out PC1/3 in the myeloid or the hematopoietic compartment did not induce any phenotype. In contrast, proopiomelanocortin (POMC)-specific PC1/3 knockout mice phenocopied global PC1/3 knockout mice, including an enlarged spleen size and a hyperinflammatory sepsis phenotype in response to mild endotoxemia. This phenotype was prevented by steroid therapy and mimicked by blocking corticoid receptors in wild-type mice. Thus, our data suggest that sepsis hypersensitivity in PC1/3 deficiency is uncoupled from immune cell intrinsic PC1/3 expression and is driven by a lack of anti-inflammatory glucocorticoids due to an impairment in the hypothalamic-pituitary-adrenal axis.

Promotion effect of proanthocyanidin on dentin remineralization via the polymer induced liquid precursor process

Proanthocyanidin (PA) has demonstrated promise as a dental biomodifier for maintaining dentin collagen integrity, yet there is limited evidence regarding its efficacy in dentin repair. The aim of this study was to investigate the effect of PA on dentin remineralization through the polymer induced liquid precursor (PILP) process, as well as to assess the mechanical properties of the restored dentin. Demineralized dentin was treated with a PA-contained remineralization medium, resulting in the formation of PA-amorphous calcium phosphate (ACP) nanoparticles via the PILP process. The kinetics and microstructure of remineralized dentin were examined through the use of Fourier transform infrared spectroscopy(FTIR), attenuated total reflectance-FTIR, scanning electron microscopy, transmission electron microscopy. The results showed that the application of PA facilitated the process of dentin remineralization, achieving completion within 48 h, demonstrating a notable reduction in time required. Following remineralization, the mechanical properties of the dentin exhibited an elastic modulus of 15.89 ± 1.70 GPa and a hardness of 0.47 ± 0.08 GPa, which were similar to those of natural dentin. These findings suggest that combining PA with the PILP process can promote dentin remineralization and improve its mechanical properties, offering a promising new approach for dentin repair in clinical practice.

Epoxy composite microspheres as a versatile platform for enhancement of chlorophyll dispersion and photostability in coatings

Chlorophyll (Chl), as a rich natural pigment, is limited in applications due to poor photostability. The hydrophobic properties of Chl attributed to the tetrapyrrole ring and terminal long-chain hydrocarbons further constrains its dispersion in aqueous coatings. In this work, chlorophyll/epoxy composite microspheres (Chl/EMs) were prepared as candidate pigments via emulsion polymerization to provide a versatile platform for enhanced dispersion and photostability. The optimal reaction temperature of 75 °C for achieving the appropriate particle size distribution of epoxy microspheres (EMs) was first determined. Chl/EMs were then prepared by (1) the combination of Chl and DGEBA in the emulsification process, or by (2) mixing Chl with m-xylylenediamine (MXDA) during curing. The effects of Chl introduction at different steps on the emulsification, curing agent diffusion, and curing process were studied using off-site microscopy observation and aggregation-induced emission technique, to clarify the structure and morphology evolution during emulsion polymerization. The particle size of the microspheres was mainly determined by the emulsification process of the epoxy precursor. Chl participates in emulsification of Chl/EMs in case (1), resulting in a large average particle size and poor particle size distribution. In case (2), the diffusion of MXDA into epoxy emulsion particles is completed within 30 min and does not impede the quicker diffusion process of Chl which was mixed with MXDA. The prepared Chl/EMs with size ranging from 1 to 10 μm create a conducive oxygen blocking environment. Compared to the complete degradation period of untreated Chl coatings, the photostability of Chl/EMs coatings increased nearly 7-fold. Remarkably, Chl/EMs exhibit superior dispersion capability in waterborne polyurethane coatings compared to pure Chl coatings. The EMs with controllable morphology and size can be used as a versatile platform for enhancing dispersion and photostability of other organic or natural dyes and pigments in waterborne coatings.

POP1 Facilitates Proliferation in Triple-Negative Breast Cancer via m6A-Dependent Degradation of CDKN1A mRNA.

Triple-negative breast cancer (TNBC) is currently the worst prognostic subtype of breast cancer, and there is no effective treatment other than chemotherapy. Processing of precursors 1 (POP1) is the most substantially up-regulated RNA-binding protein (RBP) in TNBC. However, the role of POP1 in TNBC remains clarified. A series of molecular biological experiments invitro and invivo and clinical correlation analyses were conducted to clarify the biological function and regulatory mechanism of POP1 in TNBC. Here, we identified that POP1 is significantly up-regulated in TNBC and associated with poor prognosis. We further demonstrate that POP1 promotes the cell cycle and proliferation of TNBC invitro and vivo. Mechanistically, POP1 directly binds to the coding sequence (CDS) region of CDKN1A mRNA and degrades it. The degradation process depends on the N6-methyladenosine (m6A) modification at the 497th site of CDKN1A and the recognition of this modification by YTH N6-methyladenosine RNA binding protein 2 (YTHDF2). Moreover, the m6A inhibitor STM2457 potently impaired the proliferation of POP1-overexpressed TNBC cells and improved the sensitivity to paclitaxel. In summary, our findings reveal the pivotal role of POP1 in promoting TNBC proliferation by degrading the mRNA of CDKN1A and that inhibition of m6A with STM2457 is a promising therapeutic strategy for TNBC.

Iron chelation by oral deferoxamine treatment decreased brain iron and iron signaling proteins.

Deferoxamine (DFO) and other iron chelators are clinically used for cancer and stroke. They may also be useful for Alzheimers disease (AD) to diminish iron from microbleeds. DFO may also stimulate antioxidant membrane repair which is impaired during AD. DFO, and other chelators do enter the brain despite some contrary reports. Low dose, oral DFO was given in lab chow to wildtype (WT) C57BL/6 mice to evaluate potential impact on iron levels, iron-signaling and storage proteins, and amyloid precursor protein (APP) and processing enzymes. Young WT mice do not have microbleeds or disrupted blood-brain barrier of AD mice. Iron was measured by MRI and chemically after two weeks of dietary DFO. Cerebral cortex was examined for changes in iron metabolism, antioxidant signaling, and APP processing by Western blot. DFO decreased brain iron by 18% (MRI) and decreased seven major proteins that mediate iron metabolism by at least 25%. The iron storage proteins ferritin light and heavy chain decreased by at least 30%. APP and secretase enzymes also decreased by 30%. WT mice respond to DFO with decreased APP, amyloid processing enzymes, and antioxidant repair. Potential DFO treatment for early-stage AD by DFO should consider the benefits of lowered APP and secretase enzymes.

Improved self-cleaving precipitation tags for efficient column free bioseparations

Current biological research requires simple protein bioseparation methods capable of purifying target proteins in a single step with high yields and purities. Conventional affinity tag-based approaches require specific affinity resins and expensive proteolytic enzymes for tag removal. Purification strategies based on self-cleaving aggregating tags have been previously developed to address these problems. However, these methods often utilize C-terminal cleaving contiguous inteins which suffer from premature cleavage, resulting in significant product loss during protein expression. In this work, we evaluate two novel mutants of the Mtu RecA ΔI-CM mini-intein obtained through yeast surface display for improved protein purification. When used with the elastin-like-polypeptide (ELP) precipitation tag, the novel mutants - ΔI-12 and ΔI-29 resulted in significantly higher precursor content, product purity and process yield compared to the original Mtu RecA ΔI-CM mini-intein. Product purities ranging from 68 % to 94 % were obtained in a single step for three model proteins - green fluorescent protein (GFP), maltose binding protein (MBP) and beta-galactosidase (beta-gal). Further, high cleaving efficiency was achieved after 5 h under most conditions. Overall, we have developed improved self-cleaving precipitation tags which can be used for purifying a wide range of proteins cheaply at laboratory scale.

Current Status of Transfer RNA-derived Small RNAs in Cancers

Transfer RNA-derived small RNAs (tsRNAs) are a new type of non-coding small RNAs produced by the processing and splicing of precursor or mature transfer RNAs by specific endonucleases under unfavorable conditions, such as starvation, oxidative stress, hypoxia, etc. tsRNAs have been found to be abnormally expressed in multiple types of cancers. With the development of science and technology, their regulatory mechanisms have been gradually discovered. This review summarizes the progress of tsRNAs in cancers of gastrointestinal system, breast system and reproductive system, and lays the foundation for the diagnosis and treatment of the diseases.

Small Charged Molecule-Mediated Fibrillar Mineralization: Implications for Ectopic Calcification.

Numerous small biomolecules exist in the human body and play roles in various biological and pathological processes. Small molecules are believed not to induce intrafibrillar mineralization alone. They are required to work in synergy with noncollagenous proteins (NCPs) and their analogs, e.g. polyelectrolytes, for inducing intrafibrillar mineralization, as the polymer-induced liquid-like precursor (PILP) process has been well-documented. In this study, we demonstrate that small charged molecules alone, such as sodium tripolyphosphate, sodium citrate, and (3-aminopropyl) triethoxysilane, could directly mediate fibrillar mineralization. We propose that small charged molecules might be immobilized in collagen fibrils to form the polyelectrolyte-like collagen complex (PLCC) via hydrogen bonds. The PLCC could attract CaP precursors along with calcium and phosphate ions for inducing mineralization without any polyelectrolyte additives. The small charged molecule-mediated mineralization process was evidenced by Cryo-TEM, AFM, SEM, FTIR, ICP-OES, etc., as the PLCC exhibited both characteristic features of collagen fibrils and polyelectrolyte with increased charges, hydrophilicity, and density. This might hint at one mechanism of pathological biomineralization, especially for understanding the ectopic calcification process.

Ether chain modified electrochromic polymer based on EDOT and benzene

Polar side chain plays an critical role in regulating molecular aggregation, film morphology and electrochromic properties of conjugated polymer. Here an ether chain modified conjugated polymer poly(EB-ether) based on EDOT and benzene was prepared at low oxidation potential by electrochemical method in EtOH-CH2Cl2 (v/v = 5/1) containing 0.1 M Bu4NPF6. The prepared poly(EB-ether) could achieve similar electrochromic parameters with alkoxy chain modified poly(EB-alkoxy), such as optical contrast of 35 %, response time of 0.8 s, coloration efficiency of 283 C−1 cm2, and reversible color change between dark red and blue. Electrochromic results indicate that high-performance poly(EB-ether) film could be prepared in mixed solvent containing little CH2Cl2. Therefore, the introduction of ether chain in precursor is a feasible method to decrease or avoid the use of halogenated solvent in electrochemical polymerization process of precursor.

Exportin-5 binding precedes 5′- and 3′-end processing of tRNA precursors in Drosophila

Exportin5 (Exp5) is the major microRNA (miRNA) nuclear export factor and recognizes structural features of pre-miRNA hairpins, while it also exports other minihelix-containing RNAs. In Drosophila, Exp5 is suggested to play a major role in tRNA export because the gene encoding the canonical tRNA export factor Exportin-t is missing in its genome. To understand molecular functions of fly Exp5, we studied the Exp5/RNA interactome in the cell line S2R+ using the CLIP (crosslinking and immunoprecipitation) technology. The CLIP experiment captured known substrates such as tRNAs and miRNAs, and detected candidates of novel Exp5 substrates including various mRNAs and long non-coding RNAs (lncRNAs). Some mRNAs and lncRNAs enriched PAR-CLIP tags compared to their expression levels, suggesting selective binding of Exp5 to them. Intronless mRNAs tended to enrich PAR-CLIP tags, therefore we proposed that Exp5 might play a role in export of specific classes of mRNAs/lncRNAs. This result suggested that Drosophila Exp5 might have a wider variety of substrates than initially thought. Surprisingly, Exp5 CLIP reads often contained sequences corresponding to the flanking 5’-leaders and 3’-trailers of tRNAs, which were thought to be removed prior to nuclear export. In fact, we found pre-tRNAs before end-processing were present in the cytoplasm, supporting the idea that tRNA end-processing is a cytoplasmic event. In summary, our results provide a genome-wide list of Exp5 substrate candidates, and suggest that flies may lack a mechanism to distinguish pre-tRNAs with or without the flanking sequences.

LARP3, LARP7, and MePCE are involved in the early stage of human telomerase RNA biogenesis

Human telomerase assembly is a highly dynamic process. Using biochemical approaches, we find that LARP3 and LARP7/MePCE are involved in the early stage of human telomerase RNA (hTR) and that their binding to RNA is destabilized when the mature form is produced. LARP3 plays a negative role in preventing the processing of the 3′-extended long (exL) form and the binding of LARP7 and MePCE. Interestingly, the tertiary structure of the exL form prevents LARP3 binding and facilitates hTR biogenesis. Furthermore, low levels of LARP3 promote hTR maturation, increase telomerase activity, and elongate telomeres. LARP7 and MePCE depletion inhibits the conversion of the 3′-extended short (exS) form into mature hTR and the cytoplasmic accumulation of hTR, resulting in telomere shortening. Taken together our data suggest that LARP3 and LARP7/MePCE mediate the processing of hTR precursors and regulate the production of functional telomerase.

De‐Intercalation of Iodoplumbate(DMSO)x Complex for Uniaxially Oriented Halide Perovskite Thin‐Film Solar Cells

AbstractOrganic lead halide perovskite solar cells (PSCs) have become a viable alternative for next‐generation photovoltaic systems. The significance of reproducibly processing perovskite with less defects comes from the fact that imperfections have a major impact on the solar cell's performance and long‐term stability. Although it is well known that cautious precursor processing has a significant influence on perovskite defect generation, there haven't been extensive investigations on the serial associations between precursor processing, perovskite orientation, and defect generation in PSCs. Making use of a unique precursor chemistry treatment technique that facilitates uniaxially oriented perovskite growth, it is aimed to mitigate defects of sequentially spin‐coated perovskite. Through the temperature‐dependent configurational entropic effect on coordination between iodoplumbate and dimethylsulfoxide (DMSO), a DMSO de‐intercalation processing method is developed. This method enables the induction of uniaxially‐oriented α‐FA0.9MA0.1PbI3‐xBrx (FA: formamidnium, MA: methylammomnium, x < 0.13) perovskite growth parallel to substrates. As a result, this processing delivered significant advances in power conversion efficiency (24.02%) and ambient operational stability under light. This straightforward technique provides a accesible process for producing efficient and stable perovskite solar cells, enabling uniaxially oriented perovskite fabrication without complicated procedures or additional substances.

Over 19% Efficient Inverted Organic Photovoltaics Featuring a Molecularly Doped Metal Oxide Electron-Transporting Layer.

Molecular doping is commonly utilized to tune the charge transport properties of organic semiconductors. However, applying this technique to electrically dope inorganic materials like metal oxide semiconductors is challenging due to the limited availability of molecules with suitable energy levels and processing characteristics. Herein, n-type doping of zinc oxide (ZnO) films is demonstrated using 1,3-dimethylimidazolium-2-carboxylate (CO2-DMI), a thermally activated organic n-type dopant. Adding CO2-DMI into the ZnO precursor solution and processing it atop a predeposited indium oxide (InOx) layer yield InOx/n-ZnO heterojunctions with increased electron field-effect mobility of 32.6 cm2 V-1 s-1 compared to 18.5 cm2 V-1 s-1 for the pristine InOx/ZnO bilayer. The improved electron transport originates from the ZnO's enhanced crystallinity, reduced hydroxyl concentrations, and fewer oxygen vacancy groups upon doping. Applying the optimally doped InOx/n-ZnO heterojunctions as the electron-transporting layers (ETLs) in organic photovoltaics (OPVs) yields cells with improved power conversion efficiency of 19.06%, up from 18.3% for devices with pristine ZnO, and 18.2% for devices featuring the undoped InOx/ZnO ETL. It is shown that the all-around improved OPV performance originates from synergistic effects associated with CO2-DMI doping of the thermally grown ZnO, highlighting its potential as an electronic dopant for ZnO and potentially other metal oxides.

Enhanced microwave absorption in graphene-based composites: A study on the synergistic effect of ferrite integration and electromagnetic coupling

Graphene integration with magnetic particles demonstrates a synergistic enhancement in dielectric and magnetic loss properties, facilitating the realization of absorbing materials that are strong, broadband, lightweight, and thin. This study achieved uniform dispersion of ferrite on the surface of in-situ synthesized high-conductivity graphene, utilizing an economical liquid glucose precursor and cobalt ferrite sintering process. An interface consisting of iron carbide and cobalt-iron alloy forms between the graphene and cobalt ferrite, significantly enhancing the samples’ microwave absorption performance. Furthermore, the magnetic loss is notably enhanced through the coupling of soft and hard magnetic materials. Consequently, a composite material consisting of Graphene/Fe3C/CoFe2/CoFe2O4, with a minimal thickness of 1.85 mm, demonstrated an impressive minimum reflection loss of −48.8 dB and a notable absorption bandwidth extending over 4.04 GHz. This research will offer an effective approach for developing high-performance microwave absorption materials using graphene-based composite magnetic materials.

Principles of miRNA/miRNA* function in plant MIRNA processing.

MicroRNAs (miRNAs) are essential regulators of gene expression, defined by their unique biogenesis, which requires the precise excision of the small RNA from an imperfect fold-back precursor. Unlike their animal counterparts, plant miRNA precursors exhibit variations in sizes and shapes. Plant MIRNAs can undergo processing in a base-to-loop or loop-to-base direction, with DICER-LIKE1 (DCL1) releasing the miRNA after two cuts (two-step MIRNAs) or more (sequential MIRNAs). In this study, we demonstrate the critical role of the miRNA/miRNA* duplex region in the processing of miRNA precursors. We observed that endogenous MIRNAs frequently experience suboptimal processing in vivo due to mismatches in the miRNA/miRNA* duplex, a key region that fine-tunes miRNA levels. Enhancing the interaction energy of the miRNA/miRNA* duplex in two-step MIRNAs results in a substantial increase in miRNA levels. Conversely, sequential MIRNAs display distinct and specific requirements for the miRNA/miRNA* duplexes along their foldback structure. Our work establishes a connection between the miRNA/miRNA* structure and precursor processing mechanisms. Furthermore, we reveal a link between the biological function of miRNAs and the processing mechanism of their precursors with the evolution of plant miRNA/miRNA* duplex structures.

Lamotrigine-mediated rescue of RsgA-deficient Escherichia coli reveals another role of IF2 in ribosome biogenesis.

RsgA is a late-stage ribosome biogenesis factor. Earlier, infB (IF2) was isolated as a multicopy suppressor of the Escherichia coli ΔrsgA strain. How IF2 rescued the strain growth remained unclear. This study reveals that (i) the multicopy infB-mediated growth rescue of E. coli ΔrsgA and the processing of 17S precursor to 16S rRNA in the strain are enhanced upon simultaneous overexpression of initiator tRNA and (ii) a conformer of IF2, whose occurrence increases when IF2 is overproduced or when E. coli ΔrsgA is treated with Ltg (an anticonvulsant drug that binds to domain II of IF2), compensates for the function of RsgA. Thus, this study reveals yet another role of IF2 in ribosome biogenesis.