The p53 isoforms are differentially modified by Mdm2

The discovery that the single p53 gene encodes several different p53 protein isoforms has initiated a flurry of research into the function and regulation of these novel p53 proteins. Full-length p53 protein level is primarily regulated by the E3-ligase Mdm2, which promotes p53 ubiquitination and degradation. Here, we report that all of the novel p53 isoforms are ubiquitinated and degraded to varying degrees in an Mdm2-dependent and -independent manner, and that high-risk human papillomavirus can degrade some but not all of the novel isoforms, demonstrating that full-length p53 and the p53 isoforms are differentially regulated. In addition, we provide the first evidence that Mdm2 promotes the NEDDylation of p53β. Altogether, our data indicates that Mdm2 can distinguish between the p53 isoforms and modify them differently.     

Multiomic Metabolic Enrichment Network Analysis Reveals Metabolite–Protein Physical Interaction Subnetworks Altered in Cancer

Metabolism is recognized as an important driver of cancer progression and other complex diseases, but global metabolite profiling remains a challenge. Protein expression profiling is often a poor proxy since existing pathway enrichment models provide an incomplete mapping between the proteome and metabolism. To overcome these gaps, we introduce multiomic metabolic enrichment network analysis (MOMENTA), an integrative multiomic data analysis framework for more accurately deducing metabolic pathway changes from proteomics data alone in a gene set analysis context by leveraging protein interaction networks to extend annotated metabolic models. We apply MOMENTA to proteomic data from diverse cancer cell lines and human tumors to demonstrate its utility at revealing variation in metabolic pathway activity across cancer types, which we verify using independent metabolomics measurements. The novel metabolic networks we uncover in breast cancer and other tumors are linked to clinical outcomes, underscoring the pathophysiological relevance of the findings.     

Highly specialized Cretaceous beetle parasitoids (Ripiphoridae) identified with optimized visualization of microstructures

Extremely miniaturized longipedes insects (body length c. 0.3 mm) embedded in two pieces of Cretaceous amber from Myanmar are described and interpreted. Using inverted fluorescence and light microscopy for detailed analysis of microstructures, the inclusions were identified as primary larvae of the beetle family Ripiphoridae, subfamily Ripidiinae. While the structure of thoracic and abdominal segments including appendages corresponds well with the groundplan known in recent members of Ripidiinae, a curved prosternal ridge with prominent spines (each c. 5 μm), the reduced condition of stemmata and antennae and the lack of sharp mandibles are unique features within the entire family, apparently apomorphies of the longipedes larvae. A sinuate prosternal edge with a dense row of spines (prosternoctenidium) might be homologous with ‘head ctenidia’ in some previously described miniaturized conicocephalate larvae, but further investigation is needed. The morphological differences between the head of longipedes larvae and extant Ripidiinae are interpreted as adaptations to different groups of hosts and life strategies. Palaeoethology of the longipedes larvae is briefly discussed. In addition, the systematic placement of conicocephalate larvae from Canadian, Myanmar and Russian Cretaceous ambers, already interpreted by various authors as primary instars within Coleopterida (assigned to either Strepsiptera or to the coleopteran Tenebrionoidea: Ripiphoridae), is discussed.     

Alkaloids of Dyera costulata

Six bisindole alkaloids have been isolated from the leaves of Dyera costulata (Apocynaceae). One is the known ochrolifuanine A and the others are the novel ochrolifuanines E and F, and the 18-dehydroochrolifuanines A, E and F.     

Differential scanning calorimetric study of the thermal unfolding of beta-lactamase I from Bacillus cereus.

The irreversible thermal unfolding of the class A beta-lactamase I from Bacillus cereus has been investigated at pH 7.0, using differential scanning calorimetry (DSC) and inactivation kinetic techniques. DSC transitions showed a single peak with a denaturation enthalpy of 646 kJ.mol-1 and were moderately scan rate dependent, suggesting that the process was partially kinetically controlled. The inactivation kinetics at constant temperature showed that the irreversible denaturation of the enzyme occurs as the sum of two exponential terms whose amplitudes are strongly temperature dependent within the transition range so that, at the lowest temperatures within this interval, irreversible inactivation would proceed mainly through the slow phase. The fraction of irreversibly denatured enzyme (D) as a function of temperature for a given scanning rate was calculated by numerical integration of the kinetic equation with temperature, using previously determined kinetic parameters. This D form was the most populated of the unfolded states only at temperatures well above the maximum in the calorimetric transition. Combination of the results of kinetic and DSC experiments has allowed us to separate the contribution of the final D state to the excess enthalpy change from the contribution arising from the reversibly denatured forms of the enzyme (I(i), i = 1,..., n), with the resulting conclusion that the scan rate dependence of the calorimetric traces was the result of two different dynamic effects, viz., the irreversible step and a slow relaxation process during formation of the reversibly denatured intermediate states. Finally, the problems of using results obtained at a single scan rate to validate the two-state kinetic model are commented on.     

Extracellular targeting of the vacuolar tobacco proteins AP24, chitinase and β-1,3-glucanase in transgenic plants

The Nicotiana tabacum ap24 gene encoding a protein with antifungal activity toward Phytophthora infestans has been characterized. Analysis of cDNA clones revealed that at least three ap24-like genes are induced in tobacco upon infection with tobacco mosaic virus. Amino acid sequencing of the purified protein showed that AP24 is synthesized as a preproprotein from which an amino-terminal signal peptide and a carboxyl-terminal propeptide (CTPP) are cleaved off during post-translational processing. The functional role of the CTPP was investigated by expressing chimeric genes encoding either wild-type AP24 or a mutant protein lacking the CTPP. Plants expressing the wild-type construct resulted in proteins properly sorted to the vacuole. In contrast, the proteins produced in plants expressing the mutant construct were secreted extracellularly, indicating that the CTPP is necessary for targeting of AP24 to the vacuoles. Similar results were obtained for vacuolar chitinases and -1,3-glucanases of tobacco. The extracellularly targeted mutant proteins were shown to have retained their biological activity. Together, these results suggest that within all vacuolar pathogenesis-related proteins the targeting information resides in a short carboxyl-terminal propeptide which is removed during or after transport to the plant vacuole.     

A meta-analysis on morphological,physiological and biochemical responses of plants with PGPR inoculation under drought stress

Plant growth-promoting rhizobacteria (PGPR) can help plants to resist drought stress. However, the mechanisms of how PGPR inoculation affect plant status under drought remain incompletely understood. We performed a meta-analysis of plant response to PGPR inoculation by compiling data from 57 PGPR-inoculation studies, including 2, 387 paired observations on morphological, physiological and biochemical parameters under drought and well-watered conditions. We compare the PGPR effect on plants performances among different groups of controls and treatments. Our results reveal that PGPR enables plants to restore themselves from drought-stressed to near a well-watered state, and that C4 plants recover better from drought stress than C3 plants. Furthermore, PGPR is more effective underdrought than well-watered conditions in increasing plant biomass, enhancing photosynthesis and inhibiting oxidant damage, and the responses of C4 plants to the PGPR effect was stronger than that of C3 plants under drought conditions. Additionally, PGPR belonging to different taxa and PGPR with different functional traits have varying degrees of drought-resistance effects on plants. These results are important to improve our understanding of the PGPR beneficial effects on enhanced drought-resistance of plants.     

Comparative Transcriptome Analyses Reveal Genes Related to Spine Development in Cucumber (<i>Cucumis sativus</i>)

Fruit spine is an important quality trait of cucumber. To better understand the molecular basis of cucumber spine development and function, RNA-Seq was performed to identify differentially expressed genes (DEGs) in fruit spines of different development stages, namely, 8 days before anthesis (SpBA8), anthesis (SpA) and 8 days after anthesis (SpAA8). Stage-wise comparisons obtained 2,259 (SpBA8 vs. SpA), 4,551 (SpA vs. SpAA8), and 5,290 (SpBA8 vs. SpAA8) DEGs. All the DEGs were classified into eight expression clusters by trend analysis. Among these DEGs, in addition to the Mict, Tril, CsTTG1, CsMYB6, NS, and Tu genes that have been reported to regulate fruit spine formation, we found that the CsHDG11, CsSCL8, CsSPL8, CsZFP6 and CsZFP8 may also be involved in spine development in cucumber. Our study provides a theoretical basis for further research on molecular mechanisms of spine development in cucumber.     

Alcaloides du Strychnos tchibangensis

The structure of a new bisindole alkaloid has been elucidated by chemical correlation and analysis of ¹³C NMR spectra.