Intrinsic disorder: A term to define the specific physicochemical characteristic of protein conformational heterogeneity.

In his commentary in this issue of Molecular Cell,1 Struhl reasons that the term "intrinsically disordered regions" represents a vague and confusing concept for protein function. However, the term "intrinsically disordered" highlights the important physicochemical characteristic of conformational heterogeneity. Thus, "intrinsically disordered" is the counterpart to the term "folded, " with neither term having specific functional implications.

Infants Infected with Respiratory Syncytial Virus Generate Potent Neutralizing Antibodies that Lack Somatic Hypermutation.

Respiratory syncytial virus (RSV) is a leading cause of infant mortality, and there are currently no licensed vaccines to protect this vulnerable population. A comprehensive understanding of infant antibody responses to natural RSV infection would facilitate vaccine development. Here, we isolated more than 450 RSV fusion glycoprotein (F)-specific antibodies from 7 RSV-infected infants and found that half of the antibodies recognized only two antigenic sites. Antibodies targeting both sites showed convergent sequence features, and structural studies revealed the molecular basis for their recognition of RSV F. A subset of antibodies targeting one of these sites displayed potent neutralizing activity despite lacking somatic mutations, and similar antibodies were detected in RSV-naive B cell repertoires, suggesting that expansion of these B cells in infants may be possible with suitably designed vaccine antigens. Collectively, our results provide fundamental insights into infant antibody responses and a framework for the rational design of age-specific RSV vaccines.

Intrinsically disordered proteins in cellular signalling and regulation.

Intrinsically disordered proteins (IDPs) are important components of the cellular signalling machinery, allowing the same polypeptide to undertake different interactions with different consequences. IDPs are subject to combinatorial post-translational modifications and alternative splicing, adding complexity to regulatory networks and providing a mechanism for tissue-specific signalling. These proteins participate in the assembly of signalling complexes and in the dynamic self-assembly of membrane-less nuclear and cytoplasmic organelles. Experimental, computational and bioinformatic analyses combine to identify and characterize disordered regions of proteins, leading to a greater appreciation of their widespread roles in biological processes.

Glutamine-rich regions of the disordered CREB transactivation domain mediate dynamic intra- and intermolecular interactions.

The cyclic AMP response element (CRE) binding protein (CREB) is a transcription factor that contains a 280-residue N-terminal transactivation domain and a basic leucine zipper that mediates interaction with DNA. The transactivation domain comprises three subdomains, the glutamine-rich domains Q1 and Q2 and the kinase inducible activation domain (KID). NMR chemical shifts show that the isolated subdomains are intrinsically disordered but have a propensity to populate local elements of secondary structure. The Q1 and Q2 domains exhibit a propensity for formation of short ß-hairpin motifs that function as binding sites for glutamine-rich sequences. These motifs mediate intramolecular interactions between the CREB Q1 and Q2 domains as well as intermolecular interactions with the glutamine-rich Q1 domain of the TATA-box binding protein associated factor 4 (TAF4) subunit of transcription factor IID (TFIID). Using small-angle X-ray scattering, NMR, and single-molecule Förster resonance energy transfer, we show that the Q1, Q2, and KID regions remain dynamically disordered in a full-length CREB transactivation domain (CREBTAD) construct. The CREBTAD polypeptide chain is largely extended although some compaction is evident in the KID and Q2 domains. Paramagnetic relaxation enhancement reveals transient long-range contacts both within and between the Q1 and Q2 domains while the intervening KID domain is largely devoid of intramolecular interactions. Phosphorylation results in expansion of the KID domain, presumably making it more accessible for binding the CBP/p300 transcriptional coactivators. Our study reveals the complex nature of the interactions within the intrinsically disordered transactivation domain of CREB and provides molecular-level insights into dynamic and transient interactions mediated by the glutamine-rich domains.

The smallest functional antibody fragment: Ultralong CDR H3 antibody knob regions potently neutralize SARS-CoV-2.

Cows produce antibodies with a disulfide-bonded antigen-binding domain embedded within ultralong heavy chain third complementarity determining regions. This "knob" domain is analogous to natural cysteine-rich peptides such as knottins in that it is small and stable but can accommodate diverse loops and disulfide bonding patterns. We immunized cattle with SARS-CoV-2 spike and found ultralong CDR H3 antibodies that could neutralize several viral variants at picomolar IC50 potencies in vitro and could protect from disease in vivo. The independent CDR H3 peptide knobs were expressed and maintained the properties of the parent antibodies. The knob interaction with SARS-CoV-2 spike was revealed by electron microscopy, X-ray crystallography, NMR spectroscopy, and mass spectrometry and established ultralong CDR H3-derived knobs as the smallest known recombinant independent antigen-binding fragment. Unlike other vertebrate antibody fragments, these knobs are not reliant on the immunoglobulin domain and have potential as a new class of therapeutics.

Microtubule-Mediated Regulation of ß2AR Translation and Function in Failing Hearts.

BACKGROUND: ß1AR (beta-1 adrenergic receptor) and ß2AR (beta-2 adrenergic receptor)-mediated cyclic adenosine monophosphate signaling has distinct effects on cardiac function and heart failure progression. However, the mechanism regulating spatial localization and functional compartmentation of cardiac ß-ARs remains elusive. Emerging evidence suggests that microtubule-dependent trafficking of mRNP (messenger ribonucleoprotein) and localized protein translation modulates protein compartmentation in cardiomyocytes. We hypothesized that ß-AR compartmentation in cardiomyocytes is accomplished by selective trafficking of its mRNAs and localized translation. METHODS: The localization pattern of ß-AR mRNA was investigated using single molecule fluorescence in situ hybridization and subcellular nanobiopsy in rat cardiomyocytes. The role of microtubule on ß-AR mRNA localization was studied using vinblastine, and its effect on receptor localization and function was evaluated with immunofluorescent and high-throughput Förster resonance energy transfer microscopy. An mRNA protein co-detection assay identified plausible ß-AR translation sites in cardiomyocytes. The mechanism by which ß-AR mRNA is redistributed post-heart failure was elucidated by single molecule fluorescence in situ hybridization, nanobiopsy, and high-throughput Förster resonance energy transfer microscopy on 16 weeks post-myocardial infarction and detubulated cardiomyocytes. RESULTS: ß1AR and ß2AR mRNAs show differential localization in cardiomyocytes, with ß1AR found in the perinuclear region and ß2AR showing diffuse distribution throughout the cell. Disruption of microtubules induces a shift of ß2AR transcripts toward the perinuclear region. The close proximity between ß2AR transcripts and translated proteins suggests that the translation process occurs in specialized, precisely defined cellular compartments. Redistribution of ß2AR transcripts is microtubule-dependent, as microtubule depolymerization markedly reduces the number of functional receptors on the membrane. In failing hearts, both ß1AR and ß2AR mRNAs are redistributed toward the cell periphery, similar to what is seen in cardiomyocytes undergoing drug-induced detubulation. This suggests that t-tubule remodeling contributes to ß-AR mRNA redistribution and impaired ß2AR function in failing hearts. CONCLUSIONS: Asymmetrical microtubule-dependent trafficking dictates differential ß1AR and ß2AR localization in healthy cardiomyocyte microtubules, underlying the distinctive compartmentation of the 2 ß-ARs on the plasma membrane. The localization pattern is altered post-myocardial infarction, resulting from transverse tubule remodeling, leading to distorted ß2AR-mediated cyclic adenosine monophosphate signaling.

Multivalency enables unidirectional switch-like competition between intrinsically disordered proteins.

Intrinsically disordered proteins must compete for binding to common regulatory targets to carry out their biological functions. Previously, we showed that the activation domains of two disordered proteins, the transcription factor HIF-1α and its negative regulator CITED2, function as a unidirectional, allosteric molecular switch to control transcription of critical adaptive genes under conditions of oxygen deprivation. These proteins achieve transcriptional control by competing for binding to the TAZ1 domain of the transcriptional coactivators CREB-binding protein (CBP) and p300 (CREB: cyclic-AMP response element binding protein). To characterize the mechanistic details behind this molecular switch, we used solution NMR spectroscopy and complementary biophysical methods to determine the contributions of individual binding motifs in CITED2 to the overall competition process. An N-terminal region of the CITED2 activation domain, which forms a helix when bound to TAZ1, plays a critical role in initiating competition with HIF-1α by enabling formation of a ternary complex in a process that is highly dependent on the dynamics and disorder of the competing partners. Two other conserved binding motifs in CITED2, the LPEL motif and an aromatic/hydrophobic motif that we term ϕC, function synergistically to enhance binding of CITED2 and inhibit rebinding of HIF-1α. The apparent unidirectionality of competition between HIF-1α and CITED2 is lost when one or more of these binding regions is altered by truncation or mutation of the CITED2 peptide. Our findings illustrate the complexity of molecular interactions involving disordered proteins containing multivalent interaction motifs and provide insight into the unique mechanisms by which disordered proteins compete for occupancy of common molecular targets within the cell.

Nasal and pharyngeal mucosal immunity to poliovirus in children following routine immunization with inactivated polio vaccine (IPV) in the United States of America.

BACKGROUND: Although polioviruses (PVs) replicate in lymphoid tissue of both the pharynx and ileum, research on polio vaccine-induced mucosal immunity has predominantly focused on intestinal neutralizing and binding antibody levels measured in stool. METHODS: To investigate the extent to which routine immunization with intramuscularly injected inactivated polio vaccine (IPV) may induce nasal and pharyngeal mucosal immunity, we measured PV type-specific neutralization and immunoglobulin (Ig) G, IgA, and IgM levels in nasal secretions, adenoid cell supernatants, and sera collected from 12 children, aged 2 to 5 years, undergoing planned adenoidectomies. All participants were routinely immunized with IPV and had no known contact with live PVs. RESULTS: PV-specific mucosal neutralization was detected in nasal and adenoid samples, mostly from children who had previously received four IPV doses. Across the three PV serotypes, both nasal (Spearman's rho ≥ 0.87, p≤0.0003 for all) and adenoid (Spearman's rho ≥0.57, p≤0.05 for all) neutralization titers correlated with serum neutralization titers. In this small study sample, there was insufficient evidence to determine which Ig isotype(s) was correlated with neutralization. CONCLUSIONS: Our findings provide policy-relevant evidence that routine immunization with IPV may induce nasal and pharyngeal mucosal immunity. The observed correlations of nasal and pharyngeal mucosal neutralization with serum neutralization contrast with previous observations of distinct intestinal and serum responses to PV vaccines. Further research is warranted to determine which antibody isotype(s) correlate with polio vaccine-induced nasal and pharyngeal mucosal neutralizing activity and to understand the differences from intestinal mucosal immunity.

Probing the Dissociation Pathway of a Kinetically Labile Transthyretin Mutant.

Aggregation of transthyretin (TTR) is associated with devastating amyloid diseases. Amyloidosis begins with the dissociation of the native homotetramer (a dimer of dimers) to form a monomeric intermediate that assembles into pathogenic aggregates. This process is accelerated in vitro at low pH, but the process by which TTR dissociates and reassembles at neutral pH remains poorly characterized due to the low population of intermediates. Here, we use 19F-nuclear magnetic resonance (NMR) and a highly sensitive trifluoromethyl probe to determine the relative populations of the species formed by the dissociation of a destabilized variant, A25T. The A25T mutation perturbs both the strong dimer and weak dimer-dimer interfaces. A tetramer ⇌ dimer ⇌ monomer (TDM) equilibrium model is proposed to account for concentration- and temperature-dependent population changes. Thermodynamic and kinetic parameters and activation energetics for dissociation of the native A25T tetramer, as well as a destabilized alternative tetramer (T*) with a mispacked F87 side chain, were extracted by van't Hoff and 19F-NMR line shape analysis, saturation transfer, and transition state theory. Chemical shifts for the dimer and T* species are degenerate for 19F and methyl probes close to the strong dimer interface, implicating interfacial perturbation as a common structural feature of these destabilized species. All-atom molecular dynamics simulations further suggest more frequent F87 ring flipping on the nanosecond time scale in the A25T dimer than in the native A25T tetramer. Our integrated approach offers quantitative insights into the energy landscape of the dissociation pathway of TTR at neutral pH.

Structural and dynamic studies of DNA recognition by NF-κB p50 RHR homodimer using methyl NMR spectroscopy.

Protein dynamics involving higher-energy sparsely populated conformational substates are frequently critical for protein function. This study describes the dynamics of the homodimer (p50)2 of the p50 Rel homology region (RHR) of the transcription factor NF-κB, using 13C relaxation dispersion experiments with specifically (13C, 1H)-labeled methyl groups of Ile (δ), Leu and Val. Free (p50)2 is highly dynamic in solution, showing µs-ms relaxation dispersion consistent with exchange between the ground state and higher energy substates. These fluctuations propagate from the DNA-binding loops through the core of the domain. The motions are damped in the presence of κB DNA, but the NMR spectra of the DNA complexes reveal multiple local conformations of the p50 RHR homodimer bound to certain κB DNA sequences. Varying the length and sequence of κB DNA revealed two factors that promote a single bound conformation for the complex: the length of the κB site in the duplex and a symmetrical sequence of guanine nucleotides at both ends of the recognition motif. The dynamic nature of the DNA-binding loops, together with the multiple bound conformations of p50 RHR with certain κB sites, is consistent with variations in the transcriptional activity of the p50 homodimer with different κB sequences.

A phosphorylation-dependent switch in the disordered p53 transactivation domain regulates DNA binding.

The tumor-suppressor p53 is a critical regulator of the cellular response to DNA damage and is tightly regulated by posttranslational modifications. Thr55 in the AD2 interaction motif of the N-terminal transactivation domain functions as a phosphorylation-dependent regulatory switch that modulates p53 activity. Thr55 is constitutively phosphorylated, becomes dephosphorylated upon DNA damage, and is subsequently rephosphorylated to facilitate dissociation of p53 from promoters and inactivate p53-mediated transcription. Using NMR and fluorescence spectroscopy, we show that Thr55 phosphorylation inhibits DNA-binding by enhancing competitive interactions between the disordered AD2 motif and the structured DNA-binding domain (DBD). Nonphosphorylated p53 exhibits positive cooperativity in binding DNA as a tetramer. Upon phosphorylation of Thr55, cooperativity is abolished and p53 binds initially to cognate DNA sites as a dimer. As the concentration of phosphorylated p53 is further increased, a second dimer binds and causes p53 to dissociate from the DNA, resulting in a bell-shaped binding curve. This autoinhibition is driven by favorable interactions between the DNA-binding surface of the DBD and the multiple phosphorylated AD2 motifs within the tetramer. These interactions are augmented by additional phosphorylation of Ser46 and are fine-tuned by the proline-rich domain (PRD). Removal of the PRD strengthens the AD2-DBD interaction and leads to autoinhibition of DNA binding even in the absence of Thr55 phosphorylation. This study reveals the molecular mechanism by which the phosphorylation status of Thr55 modulates DNA binding and controls both activation and termination of p53-mediated transcriptional programs at different stages of the cellular DNA damage response.

A transthyretin monomer intermediate undergoes local unfolding and transient interaction with oligomers in a kinetically concerted aggregation pathway.

Transthyretin (TTR) amyloidosis is associated with tissue deposition of TTR aggregates. TTR aggregation is initiated by dissociation of the native tetramer to form a monomeric intermediate, which locally unfolds and assembles into soluble oligomers and higher-order aggregates. However, a detailed mechanistic understanding requires kinetic and structural characterization of the low population intermediates formed. Here, we show that the monomeric intermediate exchanges with an ensemble of oligomers on the millisecond timescale. This transient and reversible exchange causes broadening of the 19F resonance of a trifluoromethyl probe coupled to the monomeric intermediate at S85C. We show the 19F linewidth and R2 relaxation rate increase with increasing concentration of the oligomer. Furthermore, introduction of 19F probes at additional TTR sites yielded distinct 19F chemical shifts for the TTR tetramer and monomer when the trifluoromethyl probe was attached at S100C, located near the same subunit interface as S85C, but not with probes attached at S46C or E63C, which are distant from any interfaces. The 19F probe at E63C shows that part of the DE loop, which is solvent accessible in the tetramer, becomes more buried in the NMR-visible oligomers. Finally, using backbone amides as probes, we show that parts of the EF helix and H-strand become highly flexible in the otherwise structured monomeric intermediate at acidic pH. We further find that TTR aggregation can be reversed by increasing pH. Taken together, this work provides insights into location-dependent conformational changes in the reversible early steps of a kinetically concerted TTR aggregation pathway.

Effects of schistosomes on host anti-viral immune response and the acquisition, virulence, and prevention of viral infections: A systematic review.

Although a growing number of studies suggest interactions between Schistosoma parasites and viral infections, the effects of schistosome infections on the host response to viruses have not been evaluated comprehensively. In this systematic review, we investigated how schistosomes impact incidence, virulence, and prevention of viral infections in humans and animals. We also evaluated immune effects of schistosomes in those coinfected with viruses. We screened 4,730 studies and included 103. Schistosomes may increase susceptibility to some viruses, including HIV and Kaposi's sarcoma-associated herpesvirus, and virulence of hepatitis B and C viruses. In contrast, schistosome infection may be protective in chronic HIV, Human T-cell Lymphotropic Virus-Type 1, and respiratory viruses, though further research is needed. Schistosome infections were consistently reported to impair immune responses to hepatitis B and possibly measles vaccines. Understanding the interplay between schistosomes and viruses has ramifications for anti-viral vaccination strategies and global control of viral infections.

Prediction of Compound Plasma Concentration-Time Profiles in Mice Using Random Forest.

Pharmacokinetic (PK) parameters such as clearance (CL) and volume of distribution (Vd) have been the subject of previous in silico predictive models. However, having information of the concentration over time profile explicitly can provide additional value like time above MIC or AUC, etc., to understand both the efficacy and safety-related aspects of a compound. In this work, we developed machine learning models for plasma concentration-time profiles after both i.v. and p.o. dosing for a series of 17 in-house projects. For explanatory variables, MACCS Keys chemical descriptors as well as in silico and experimental in vitro PK parameters were used. The predictive accuracy of random forest (RF), message passing neural network, 2-compartment models using estimated CL and Vdss, and an average model (as a control experiment) was investigated using 5-fold cross-validation (5-fold CV) and leave-one-project-out validation (LOPO-V). The predictive accuracy of RF in 5-fold CV for i.v. and p.o. plasma concentration-time profiles was the best among the models studied, with an RMSE for i.v. dosing at 0.08, 1, and 8 h of 0.245, 0.474, and 0.462, respectively, and an RMSE for p.o. dosing at 0.25, 1, and 8 h of 0.500, 0.612, and 0.509, respectively. Furthermore, by investigating the importance of the in vitro PK parameters using the Gini index, we observed that the general prior knowledge in ADME research was reflected well in the respective feature importance of in vitro parameters such as predicted human Vd (hVd) for the initial distribution, mouse intrinsic CL and unbound fraction of mouse plasma for the elimination process, and Caco2 permeability for the absorption process. Also, this model is the first model that can predict twin peaks in the concentration-time profile much better than a baseline compartment model. Because of its combination of sufficient accuracy and speed of prediction, we found the model to be fit-for-purpose for practical lead optimization.

Hypersensitive termination of the hypoxic response by a disordered protein switch.

The cellular response to hypoxia is critical for cell survival and is fine-tuned to allow cells to recover from hypoxic stress and adapt to heterogeneous or fluctuating oxygen levels. The hypoxic response is mediated by the α-subunit of the transcription factor HIF-1 (HIF-1α), which interacts through its intrinsically disordered C-terminal transactivation domain with the TAZ1 (also known as CH1) domain of the general transcriptional coactivators CBP and p300 to control the transcription of critical adaptive genes. One such gene encodes CITED2, a negative feedback regulator that attenuates HIF-1 transcriptional activity by competing for TAZ1 binding through its own disordered transactivation domain. Little is known about the molecular mechanism by which CITED2 displaces the tightly bound HIF-1α from their common cellular target. The HIF-1α and CITED2 transactivation domains bind to TAZ1 through helical motifs that flank a conserved LP(Q/E)L sequence that is essential for negative feedback regulation. Here we show that human CITED2 displaces HIF-1α by forming a transient ternary complex with TAZ1 and HIF-1α and competing for a shared binding site through its LPEL motif, thus promoting a conformational change in TAZ1 that increases the rate of HIF-1α dissociation. Through allosteric enhancement of HIF-1α release, CITED2 activates a highly responsive negative feedback circuit that rapidly and efficiently attenuates the hypoxic response, even at modest CITED2 concentrations. This hypersensitive regulatory switch is entirely dependent on the unique flexibility and binding properties of these intrinsically disordered proteins and probably exemplifies a common strategy used by the cell to respond rapidly to environmental signals.

Retrospective analysis of the potential use of virtual control groups in preclinical toxicity assessment using the eTOX database.

Virtual Control Groups (VCGs) based on Historical Control Data (HCD) in preclinical toxicity testing have the potential to reduce animal usage. As a case study we retrospectively analyzed the impact of replacing Concurrent Control Groups (CCGs) with VCGs on the treatment-relatedness of 28 selected histopathological findings reported in either rat or dog in the eTOX database. We developed a novel methodology whereby statistical predictions of treatment-relatedness using either CCGs or VCGs of varying covariate similarity to CCGs were compared to designations from original toxicologist reports; and changes in agreement were used to quantify changes in study outcomes. Generally, the best agreement was achieved when CCGs were replaced with VCGs with the highest level of similarity; the same species, strain, sex, administration route, and vehicle. For example, balanced accuracies for rat findings were 0.704 (predictions based on CCGs) vs. 0.702 (predictions based on VCGs). Moreover, we identified covariates which resulted in poorer identification of treatment-relatedness. This was related to an increasing incidence rate divergence in HCD relative to CCGs. Future databases which collect data at the individual animal level including study details such as animal age and testing facility are required to build adequate VCGs to accurately identify treatment-related effects.

Statistical analysis of preclinical inter-species concordance of histopathological findings in the eTOX database.

Preclinical inter-species concordance can increase the predictivity of observations to the clinic, potentially reducing drug attrition caused by unforeseen adverse events. We quantified inter-species concordance of histopathological findings and target organ toxicities across four preclinical species in the eTOX database using likelihood ratios (LRs). This was done whilst only comparing findings between studies with similar compound exposure (Δ|Cmax| ≤ 1 log-unit), repeat-dosing duration, and animals of the same sex. We discovered 24 previously unreported significant inter-species associations between histopathological findings encoded by the HPATH ontology. More associations with strong positive concordance (33% LR+ > 10) relative to strong negative concordance (12.5% LR- < 0.1) were identified. Of the top 10 most positively concordant associations, 60% were computed between different histopathological findings indicating potential differences in inter-species pathogenesis. We also observed low inter-species target organ toxicity concordance. For example, liver toxicity concordance in short-term studies between female rats and dogs observed an average LR+ of 1.84, and an average LR- of 0.73. This was corroborated by similarly low concordance between rodents and non-rodents for 75 candidate drugs in AstraZeneca. This work provides new statistically significant associations between preclinical species, but finds that concordance is rare, particularly between the absence of findings.

From Immunogenic Peptides to Intrinsically Disordered Proteins.

It is hard to evaluate the role of individual mentors in the genesis of important ideas. In the case of our realization that proteins do not have to be stably folded to be functional, the influence of Richard Lerner and our collaborative work in the 1980s on the conformations of immunogenic peptides provided a base level of thinking about the nature of polypeptides in water solutions that led us to formulate and develop our ideas on the importance of intrinsic disorder in proteins. This review describes how the insights gained into the behavior of peptides led directly to the realization that proteins were not only capable of being functional while disordered, but also that disorder provided a distinct functional advantage in many important cellular processes.

Vacuolar localisation of anthocyanin pigmentation in microgreen cotyledons of basil, cabbage and mustard greens does not impact on colonisation by Shiga-toxigenic Escherichia coli O157:H7.

Microgreens, the immature plants harvested after a few weeks of growth, are perceived as a heathy, nutritious food ingredient but may be susceptible to colonisation by human pathogens including Shiga-toxigenic Escherichia coli (STEC). Some microgreen cultivars accumulate anthocyanins or secrete essential oils which, when extracted or purified, have been reported to inhibit bacterial growth. Therefore, the impact of anthocyanins on bacterial colonisation by STEC (Sakai) was compared for three species that have pigmented cultivars: basil (Ocimum basilicum L.), cabbage (Brassica oleracea L.) and mustard greens (Brassica juncea L.). Inoculation with low concentrations of STEC (Sakai) (3 log10 colony forming units/ml (CFU/ml)) during seed germination resulted in extensive colonisation at the point of harvest, accumulating to âˆ¼ 8 log10 CFU/g FW in all cultivars. Bacterial colonies frequently aligned with anticlinal walls on the surface of epidermal cells of the cotyledons and, in basil, associated with peltate and capitate gland cells. Crude lysates of pigmented and non-pigmented basil cultivars had no impact on STEC (Sakai) growth rates, viability status or biofilm formation. Anthocyanins are located within plant vacuoles of these microgreen cultivars and did not affect colonisation by STEC (Sakai) and pigmentation therefore cannot be considered as a controlling factor in bacterial interactions.

Microtubules regulate cardiomyocyte transversal Young's modulus.

The field of cardiomyocyte mechanobiology is gaining significant attention, due to accumulating evidence concerning the significant role of cellular mechanical effects on the integrated function of the heart. To date, the protein titin has been demonstrated as a major contributor to the cardiomyocytes Young's modulus (YM). The microtubular network represents another potential regulator of cardiac mechanics. However, the contribution of microtubules (MTs) to the membrane YM is still understudied and has not been interrogated in the context of myocardial infarction (MI) or mechanical loading and unloading. Using nanoscale mechanoscanning ion conductance microscopy, we demonstrate that MTs contribute to cardiomyocyte transverse YM in healthy and pathological states with different mechanical loading. Specifically, we show that posttranslational modifications of MTs have differing effects on cardiomyocyte YM: Acetylation provides flexibility, whereas detyrosination imparts rigidity. Further studies demonstrate that there is no correlation between the total protein amount of acetylated and detyrosinated MT. Yet, in the polymerized-only populations, an increased level of acetylation results in a decline of detyrosinated MTs in an MI model.