Synergism of imipenem with fosfomycin associated with the active cell wall recycling and heteroresistance in Acinetobacter calcoaceticus-baumannii complex

The carbapenem-resistant Acinetobacter calcoaceticus-baumannii (ACB) complex has become an urgent threat worldwide. Here, we determined antibiotic combinations and the feasible synergistic mechanisms against three couples of ACB (A. baumannii (AB250 and A10), A. pittii (AP1 and AP23), and A. nosocomialis (AN4 and AN12)). Imipenem with fosfomycin, the most effective in the time-killing assay, exhibited synergism to all strains except AB250. MurA, a fosfomycin target encoding the first enzyme in the de novo cell wall synthesis, was observed with the wild-type form in all isolates. Fosfomycin did not upregulate murA, indicating the MurA-independent pathway (cell wall recycling) presenting in all strains. Fosfomycin more upregulated the recycling route in synergistic strain (A10) than non-synergistic strain (AB250). Imipenem in the combination dramatically downregulated the recycling route in A10 but not in AB250, demonstrating the additional effect of imipenem on the recycling route, possibly resulting in synergism by the agitation of cell wall metabolism. Moreover, heteroresistance to imipenem was observed in only AB250. Our results indicate that unexpected activity of imipenem on the active cell wall recycling concurrently with the presence of heteroresistance subpopulation to imipenem may lead to the synergism of imipenem and fosfomycin against the ACB isolates.

Natural Mutations Affect Structure and Function of gC1q Domain of Otolin-1

Otolin-1 is a scaffold protein of otoliths and otoconia, calcium carbonate biominerals from the inner ear. It contains a gC1q domain responsible for trimerization and binding of Ca2+. Knowledge of a structure–function relationship of gC1q domain of otolin-1 is crucial for understanding the biology of balance sensing. Here, we show how natural variants alter the structure of gC1q otolin-1 and how Ca2+ are able to revert some effects of the mutations. We discovered that natural substitutions: R339S, R342W and R402P negatively affect the stability of apo-gC1q otolin-1, and that Q426R has a stabilizing effect. In the presence of Ca2+, R342W and Q426R were stabilized at higher Ca2+ concentrations than the wild-type form, and R402P was completely insensitive to Ca2+. The mutations affected the self-association of gC1q otolin-1 by inducing detrimental aggregation (R342W) or disabling the trimerization (R402P) of the protein. Our results indicate that the natural variants of gC1q otolin-1 may have a potential to cause pathological changes in otoconia and otoconial membrane, which could affect sensing of balance and increase the probability of occurrence of benign paroxysmal positional vertigo (BPPV).

Genotype-Structure-Phenotype Correlations in Disease-Associated IGF1R Variants and Similarities to Those in INSR Variants

We previously reported that genotype-phenotype correlations in 12 missense variants causing severe insulin resistance, located in the second and third fibronectin type III (FnIII) domains of the insulin receptor (INSR), containing the α-β cleavage and part of insulin-binding sites. This study aimed to identify genotype-phenotype correlations in FnIII domain variants of IGF1R, a structurally related homolog of INSR, which may be associated with growth retardation, using the recently reported crystal structures of IGF1R. A structural bioinformatics analysis of five previously reported disease-associated heterozygous missense variants and a likely benign variant in the FnIII domains of IGF1R predicted that the disease-associated variants would severely impair the hydrophobic core formation and stability of the FnIII domains or affect the α-β cleavage site, while the likely benign variant would not affect the folding of the domains. A functional analysis of these variants in CHO cells showed impaired receptor processing and autophosphorylation in cells expressing the disease-associated variants, but not in those expressing the wild-type form or the likely benign variant. These results demonstrated genotype-phenotype correlations in the FnIII domain variants of <i>IGF1R</i>, which are presumably consistent with<i> </i>those of <i>INSR</i> and would help in the early diagnosis of patients with disease-associated <i>IGF1R</i> variants.

Genotype-Structure-Phenotype Correlations in Disease-Associated IGF1R Variants and Similarities to Those in INSR Variants

We previously reported that genotype-phenotype correlations in 12 missense variants causing severe insulin resistance, located in the second and third fibronectin type III (FnIII) domains of the insulin receptor (INSR), containing the α-β cleavage and part of insulin-binding sites. This study aimed to identify genotype-phenotype correlations in FnIII domain variants of IGF1R, a structurally related homolog of INSR, which may be associated with growth retardation, using the recently reported crystal structures of IGF1R. A structural bioinformatics analysis of five previously reported disease-associated heterozygous missense variants and a likely benign variant in the FnIII domains of IGF1R predicted that the disease-associated variants would severely impair the hydrophobic core formation and stability of the FnIII domains or affect the α-β cleavage site, while the likely benign variant would not affect the folding of the domains. A functional analysis of these variants in CHO cells showed impaired receptor processing and autophosphorylation in cells expressing the disease-associated variants, but not in those expressing the wild-type form or the likely benign variant. These results demonstrated genotype-phenotype correlations in the FnIII domain variants of <i>IGF1R</i>, which are presumably consistent with<i> </i>those of <i>INSR</i> and would help in the early diagnosis of patients with disease-associated <i>IGF1R</i> variants.

Summary of 26 Heavenly Bamboo Selections Evaluated for Invasive Potential in Florida

Over the course of nearly 2 decades, the resident or wild-type form of heavenly bamboo (Nandina domestica) and 25 additional selections have been evaluated for landscape performance and invasive potential in various trial locations in Florida. Overall, in northern Florida (Quincy and Citra), ‘Royal Princess’, ‘Umpqua Chief’, ‘Gulf Stream’, ‘Monfar’ (Sienna Sunrise®), ‘Emerald Sea’, ‘Greray’ (Sunray®), ‘Lemon-Lime’, ‘Murasaki’ (Flirt™), ‘SEIKA’ (Obsession™), and ‘Twilight’ performed well throughout much of the study with average ratings between 3.0 and 4.9 (1 to 5 scale). In southern Florida (Balm and Fort Pierce), ‘AKA’ (Blush Pink™), ‘Compacta’, ‘Emerald Sea’, ‘Firestorm’™, ‘Greray’, ‘Gulf Stream’, ‘Harbour Dwarf’, ‘Jaytee’ (Harbor Belle™), ‘Lemon-Lime’, ‘Monum’ (Plum Passion®), ‘Murasaki’, and ‘SEIKA’ performed well with average ratings between 3.0 and 5.0. Among selections evaluated, plant sizes were categorized as small, medium, or large, where the final plant height ranged from 20 to 129 cm, and the plant perpendicular width ranged from 15 to 100 cm. Almost three-fourths of the selections evaluated had little to no fruiting when compared with the wild-type form. ‘AKA’, ‘Chime’, ‘Filamentosa’, ‘Firehouse’, ‘Firepower’, ‘Firestorm’, ‘Greray’, ‘Lemon- Lime’, ‘Moon Bay’, and ‘SEIKA’ did not fruit at any of the trial sites. In northern Florida, small amounts of fruit (94% to 99.9% reduction) were observed for ‘Gulf Stream’, ‘Harbour Dwarf’, ‘Jaytee’, ‘Monfar’, ‘Murasaki’, ‘Royal Princess’, ‘Twilight’, and the twisted leaf selection. Moderate amounts of fruit (62% to 83% reduction) were observed for ‘Alba’, ‘Emerald Sea’, ‘Lowboy’, ‘Moyer’s Red’, and ‘Umpqua Chief’. Heavy fruiting comparable or greater than the wild type was observed for ‘Compacta’ and ‘Monum’. Pregermination seed viability ranged from 67% to 100% among fruiting selections with 5.5% to 32.0% germination in 60 days. Germination was considerably higher (58% to 82%) when the germination time was extended to 168 days. Nuclear DNA content of selections were comparable to the wild type suggesting they are diploid. Thus, ploidy level does not appear to be associated with female infertility of those little-fruiting heavenly bamboo selections. Overall, our findings revealed certain selections of heavenly bamboo that have little potential to present an ecological threat and thus merit consideration for production and use. As a result, the University of Florida(UF)/Institute of Food and Agricultural Sciences’ (IFAS) Status Assessment on Non-native Plants in Florida’s Natural Areas infraspecific taxon protocol has concluded that ‘Firepower’ and ‘Harbour Dwarf’ are noninvasive and can be recommended for production and use in Florida. In addition, due to acceptable plant performance and low to no fruiting capacity, our research supports that ‘Firehouse’, ‘AKA’, ‘Firestorm’, ‘Gulfstream’, ‘Jaytee’, ‘Monfar’, ‘Royal Princess’, ‘Greray’, ‘Lemon-Lime’, ‘Murasaki’, and ‘SEIKA’ be considered for future noninvasive status approval.

The Potential for SARS-CoV-2 to Evade Both Natural and Vaccine-induced Immunity

SARS-CoV-2 attaches to the surface of susceptible cells through extensive interactions between the receptor binding domain (RBD) of its spike protein and angiotensin converting enzyme type 2 (ACE2) anchored in cell membranes. To investigate whether naturally occurring mutations in the spike protein are able to prevent antibody binding, yet while maintaining the ability to bind ACE2 and viral infectivity, mutations in the spike protein identified in cases of human infection were mapped to the crystallographically-determined interfaces between the spike protein and ACE2 (PDB entry 6M0J), antibody CC12.1 (PDB entry 6XC2), and antibody P2B-2F6 (PDB entry 7BWJ). Both antibody binding interfaces partially overlap with the ACE2 binding interface. Among 16 mutations that map to the RBD:CC12.1 interface, 11 are likely to disrupt CC12.1 binding but not ACE2 binding. Among 12 mutations that map to the RBD:P2B-2F6 interface, 8 are likely to disrupt P2B-2F6 binding but not ACE2 binding. As expected, none of the mutations observed to date appear likely to disrupt the RBD:ACE2 interface. We conclude that SARS-CoV-2 with mutated forms of the spike protein may retain the ability to bind ACE2 while evading recognition by antibodies that arise in response to the original wild-type form of the spike protein. It seems likely that immune evasion will be possible regardless of whether the spike protein was encountered in the form of infectious virus, or as the immunogen in a vaccine. Therefore, it also seems likely that reinfection with a variant strain of SARS-CoV-2 may occur among people who recover from Covid-19, and that vaccines with the ability to generate antibodies against multiple variant forms of the spike protein will be necessary to protect against variant forms of SARS-CoV-2 that are already circulating in the human population.

Structural and Physicochemical Characterization of Rhamnolipids produced by Pseudomonas aeruginosa P6

Rhamnolipids are important biosurfactants for application in bioremediation, enhanced oil recovery, pharmaceutical, and detergent industry. In this study, rhamnolipids extracted from P. aeruginosa P6 were characterized to determine their potential fields of application. Thin-layer chromatographic analysis of the produced rhamnolipids indicated the production of two homologues: mono- and di-rhamnolipids, whose structures were verified by 1H and 13C nuclear magnetic resonance spectroscopy. Additionally, high performance liquid chromatography-mass spectrometry identified seven different rhamnolipid congeners, of which a significantly high proportion was di-rhamnolipids reaching 80.16%. Rha-Rha-C10-C10 was confirmed as the principal compound of the rhamnolipid mixture (24.30%). The rhamnolipids were capable of lowering surface tension of water to 36 mN/m at a critical micelle concentration of 0.2 g/L, and exhibited a great emulsifying activity (E24 = 63%). In addition, they showed excellent stability at pH ranges 4–8, NaCl concentrations up to 9% (w/v) and temperatures ranging from 20 to 100 °C and even after autoclaving. These results suggest that rhamnolipids, produced by P. aeruginosa P6 using the cheap substrate glycerol, are propitious for biotechnology use in extreme and complex environments, like oil reservoirs and hydrocarbon contaminated soil. Moreover, P. aeruginosa P6 may be considered, in its wild type form, as a promising industrial producer of di-RLs, which have superior characteristics for potential applications and offer outstanding commercial benefits.

Gain-of-Function Mutant p53: All the Roads Lead to Tumorigenesis

The p53 protein is mutated in about 50% of human cancers. Aside from losing the tumor-suppressive functions of the wild-type form, mutant p53 proteins often acquire inherent, novel oncogenic functions, a phenomenon termed mutant p53 gain-of-function (GOF). A growing body of evidence suggests that these pro-oncogenic functions of mutant p53 proteins are mediated by affecting the transcription of various genes, as well as by protein–protein interactions with transcription factors and other effectors. In the current review, we discuss the various GOF effects of mutant p53, and how it may serve as a central node in a network of genes and proteins, which, altogether, promote the tumorigenic process. Finally, we discuss mechanisms by which “Mother Nature” tries to abrogate the pro-oncogenic functions of mutant p53. Thus, we suggest that targeting mutant p53, via its reactivation to the wild-type form, may serve as a promising therapeutic strategy for many cancers that harbor mutant p53. Not only will this strategy abrogate mutant p53 GOF, but it will also restore WT p53 tumor-suppressive functions.