Publications by authors named "Alexandrescu A"

As of May 2023, the public health emergency of COVID-19 was lifted across the globe. However, SARS-CoV-2 infections continue to be recorded worldwide. This situation has been attributed to the ability of the virus to evade host immune responses including neutralizing antibody-derived Immunity.

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Icosahedral dsDNA viruses such as the tailed bacteriophages and herpesviruses have a conserved pathway to virion assembly that is initiated from a scaffolding protein driven procapsid formation. The dsDNA is actively packaged into procapsids, which undergo complex maturation reactions to form infectious virions. In bacteriophage P22, scaffolding protein (SP) directs the assembly of coat proteins into procapsids that have a T=7 icosahedral arrangement, en route to the formation of the mature P22 capsid.

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The 134-residue phage L decoration protein (Dec) forms a capsid-stabilizing homotrimer that has an asymmetric tripod-like structure when bound to phage L capsids. The N-termini of the trimer subunits consist of spatially separated globular OB-fold domains that interact with the virions of phage L or the related phage P22. The C-termini of the trimer form a three-stranded intertwined spike structure that accounts for nearly all the interactions that stabilize the trimer.

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Mitochondria are central to cellular metabolism; hence, their dysfunction contributes to a wide array of human diseases. Cardiolipin, the signature phospholipid of the mitochondrion, affects proper cristae morphology, bioenergetic functions, and metabolic reactions carried out in mitochondrial membranes. To match tissue-specific metabolic demands, cardiolipin typically undergoes an acyl tail remodeling process with the final step carried out by the phospholipid-lysophospholipid transacylase tafazzin.

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Domain Z7 of nuclear transcription factor ZNF711 has the consensus last metal-ligand H23 found in odd-numbered zinc fingers of this protein replaced by a phenylalanine. Ever since the discovery of ZNF711, it has been thought that Z7 is probably non-functional because of the H23F substitution. The presence of H26 three positions downstream prompted us to examine if this histidine could substitute as the last metal-ligand.

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Long-range HNCO NMR spectra for proteins show crosspeaks due to J, J, J, and J couplings. The J couplings are transmitted through hydrogen bonds and their sizes are correlated to hydrogen bond lengths. We collected long-range HNCO data at a series of temperatures for four protein structures.

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Mitochondria are central to cellular metabolism; hence, their dysfunction contributes to a wide array of human diseases including cancer, cardiopathy, neurodegeneration, and heritable pathologies such as Barth syndrome. Cardiolipin, the signature phospholipid of the mitochondrion promotes proper cristae morphology, bioenergetic functions, and directly affects metabolic reactions carried out in mitochondrial membranes. To match tissue-specific metabolic demands, cardiolipin typically undergoes an acyl tail remodeling process with the final step carried out by the phospholipid-lysophospholipid transacylase tafazzin.

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Domain Z7 of nuclear transcription factor ZNF711 has the consensus last metal-ligand H23 found in odd-numbered zinc-fingers of this protein replaced by a phenylalanine. Ever since the discovery of ZNF711 it has been thought that Z7 is probably non-functional because of the H23F substitution. The presence of H26 three positions downstream prompted us to examine if this histidine could substitute as the last metal ligand.

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Most mitochondrial proteins are targeted to the organelle by N-terminal mitochondrial targeting sequences (MTSs, or "presequences") that are recognized by the import machinery and subsequently cleaved to yield the mature protein. MTSs do not have conserved amino acid compositions, but share common physicochemical properties, including the ability to form amphipathic α-helical structures enriched with basic and hydrophobic residues on alternating faces. The lack of strict sequence conservation implies that some polypeptides can be mistargeted to mitochondria, especially under cellular stress.

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Kinesin is a motor protein, comprised of two heavy and two light chains that transports cargo along the cytoskeletal microtubule filament network. The heavy chain has a neck domain connecting the ATPase motor head responsible for walking along microtubules, with the stalk and subsequent tail domains that bind cargo. The neck domain consists of a coiled coli homodimer with about five heptad repeats, preceded by a linker region that joins to the ATPase head.

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ZNF750 is a nuclear transcription factor that activates skin differentiation and has tumor suppressor roles in several cancers. Unusually, ZNF750 has only a single zinc-finger (ZNF) domain, Z*, with an amino acid sequence that differs markedly from the CCHH family consensus. Because of its sequence differences Z* is classified as degenerate, presumed to have lost the ability to bind the zinc ion required for folding.

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This article was initially published in the Journal of Structural Biology, instead of the Journal of Structural Biology: X, due to a publisher error. We regret the inconvenience. The link to the article published in Journal of Structural Biology: X is presented below: https://www.

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NMR isotope shifts occur due to small differences in nuclear shielding when nearby atoms are different isotopes. For molecules dissolved in 1:1 HO:DO, the resulting mixture of N-H and N-D isotopes leads to a small splitting of resonances from adjacent nuclei. We used multidimensional NMR to measure isotope shifts for the proteins CUS-3iD and CspA.

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An emerging reality is the development of smart buildings and cities, which improve residents' comfort. These environments employ multiple sensor networks, whose data must be acquired and processed in real time by multiple rule engines, which trigger events that enable specific actuators. The problem is how to handle those data in a scalable manner by using multiple processing instances to maximize the system throughput.

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Mitochondria play a central role in metabolic homeostasis, and dysfunction of this organelle underpins the etiology of many heritable and aging-related diseases. Tetrapeptides with alternating cationic and aromatic residues such as SS-31 (elamipretide) show promise as therapeutic compounds for mitochondrial disorders. In this study, we conducted a quantitative structure-activity analysis of three alternative tetrapeptide analogs, benchmarked against SS-31, that differ with respect to aromatic side chain composition and sequence register.

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Hydrodynamic radii (R -values) calculated from diffusion coefficients measured by pulse-field-gradient nuclear magnetic resonance are compared for folded and unfolded proteins. For native globular proteins, the R -values increase as a power of 0.35 with molecular size, close to the scaling factor of 0.

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The present study aimed to explore the correlations between clinical, biological, imagistic and procedural factors with the risk of intra-stent restenosis (ISR) in coronary artery disease (CAD) patients after percutaneous coronary intervention (PCI). An observational cross-sectional study was conducted in a high-volume PCI center over a period of 2 years. A total of 235 consecutive patients diagnosed with angina or acute coronary syndrome treated by PCI were included in the study.

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Unlabelled: Hypertrophic cardiomyopathy (HCM) and arterial hypertension (HTN) are conditions with different pathophysiology, but both can result in left-ventricular hypertrophy (LVH). The role of left-atrial (LA) functional changes detected by two-dimensional speckle-tracking echocardiography (STE) in indicating LVH etiology is unknown.

Methods: We aimed to characterize LA mechanics using STE in LVH patients with HCM and HTN.

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The C-terminal domain of Bacillus cereus hemolysin II (HlyIIC), stabilizes the trans-membrane-pore formed by the HlyII toxin and may aid in target cell recognition. Initial efforts to determine the NMR structure of HlyIIC were hampered by cis/trans isomerization about the single proline at position 405 that leads to doubling of NMR resonances. We used the mutant P405M-HlyIIC that eliminates the cis proline to determine the NMR structure of the domain, which revealed a novel fold.

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Decoration proteins are viral accessory gene products that adorn the surfaces of some phages and viral capsids, particularly tailed dsDNA phages. These proteins often play a "cementing" role, reinforcing capsids against accumulating internal pressure due to genome packaging, or environmental insults such as extremes of temperature or pH. Many decoration proteins serve alternative functions, including target cell recognition, participation in viral assembly, capsid size determination, or modulation of host gene expression.

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The formation of appropriate neural connections during development is critical for the proper wiring and functioning of the brain. Although considerable research suggests that the specificity of synapse formation is supported by complex intercellular signaling between potential presynaptic and postsynaptic partners, the extracellular factors and the intracellular signal transduction pathways engaged in this process remain largely unknown. Using the sensory-motor neural circuit that contributes to learning in defensive withdrawal reflexes in Aplysia californica, we investigated the molecular processes governing the interactions between sensory neurons and both target and non-target motor neurons during synapse formation in culture.

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The spatial and temporal coordination of growth factor signaling is critical for both presynaptic and postsynaptic plasticity underlying long-term memory formation. We investigated the spatiotemporal dynamics of cysteine-rich neurotrophic factor (ApCRNF) signaling during the induction of activity-dependent long-term facilitation (AD-LTF) at sensory-to-motor neuron synapses that mediate defensive reflexes in We found that ApCRNF signaling is required for the induction of AD-LTF, and for training-induced early protein kinase activation and late forms of gene expression, exclusively in postsynaptic neurons. These results support the view that ApCRNF is critically involved in AD-LTF at least in part through postsynaptic mechanisms.

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Article Synopsis
  • Scaffolding proteins (SPs) are crucial for the assembly of capsid shells in various viruses, yet detailed structures are limited.
  • Researchers utilized NMR to study the mobile regions of the P22 phage SP in both its free form and when assembled into a procapsid complex.
  • The study found that while the N-terminus remains flexible, the C-terminus binds firmly within the procapsid, suggesting the N-terminus’s structure is important for the release of SP during the genome packaging in virus maturation.
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The major coat proteins of dsDNA tailed phages (order ) and herpesviruses form capsids by a mechanism that includes active packaging of the dsDNA genome into a precursor procapsid, followed by expansion and stabilization of the capsid. These viruses have evolved diverse strategies to fortify their capsids, such as non-covalent binding of auxiliary 'decoration' (Dec) proteins. The Dec protein from the P22-like phage L has a highly unusual binding strategy that distinguishes between nearly identical three-fold and quasi-three-fold sites of the icosahedral capsid.

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The use of extracorporeal membrane oxygenation (ECMO) in severe hypothermia associated with cardiac arrest has become a more frequent warming technique in specialized centers over the years with better survival outcomes compared to traditional rewarming methods. We show that a full recovery is possible, even after prolonged resuscitation. We report the case of a 36-year old male who survived approximately 4 hours of cardiopulmonary resuscitation following an unknown duration of asystole in the context of severe accidental hypothermia (24°C).

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