The Study of Protein Conformation in Solution Via Direct Sampling by Desorption Electrospray Ionization Mass Spectrometry

The direct sampling feature of liquid sample desorption electrospray ionization (DESI) allows the ionization of liquid samples without adding acids/organic solvents (i.e., without sample pretreatment). As a result, it provides a new approach for probing protein conformation in solution. In this study, it has been observed that native protein ions are generated from proteins in water by DESI. Interestingly, the intensities of the resulting protein ions appear to be higher than those generated by ESI of the proteins in water or in ammonium acetate. For protein solutions that already contain acids/organic solvents, DESI can be used to investigate the influences of these denaturants on protein conformations and the obtained results are in good agreement with spectroscopic data. In addition, online monitoring of protein conformational changes by DESI is feasible; for instance, heat-induced unfolding of ubiquitin can be traced with DESI in water without influences of organic solvents/acids. This DESI method provides a new alternative tool for the study of protein conformation in solution

1988 DWC Membership and Mailing Lists

Membership list of DWC members, 198

Mother-Offspring Relations: Prey Quality and Maternal Size Affect Egg Size of an Acariphagous Lady Beetle in Culture

We investigated mother-offspring relations in a lady beetle Stethorus punctillum Weise that utilizes spider mites as prey. Our objectives were to determine if (1) prey quality affects egg size, (2) maternal size correlates with egg size, and (3) egg size affects hatching success. We fed predators spider mites Tetranychus urticae Koch from lima bean Phaseolus lunatus L. foliage in the laboratory. Mothers of unknown body size offered high rather than low quality spider mites since birth produced larger eggs. Mothers of known body size offered only high quality spider mites, produced eggs of variable size, but mean egg size correlated positively with hind femur length. Mothers laid their eggs singly, rather than in batches, and eggs were large relative to femur size. Egg size did not affect hatch success; mean hatch rate exceeded 95% regardless of egg size. In conclusion, the quality of prey consumed by S. punctillum mothers while in the larval stage can affect their size as adults and, consequently, the size of their eggs. The behavior of laying eggs singly, the positive relationship between maternal size and mean egg size, and the high rate of egg hatch suggest that S. punctillum mothers invest heavily in offspring

The Prospects for Immigration Amendments

Obg proteins are a family of P-loop GTPases, conserved from bacteria to human. The Obg protein in Escherichia coli (ObgE) has been implicated in many diverse cellular functions, with proposed molecular roles in two global processes, ribosome assembly and stringent response. Here, using pre-steady state fast kinetics we demonstrate that ObgE is an anti-association factor, which prevents ribosomal subunit association and downstream steps in translation by binding to the 50S subunit. ObgE is a ribosome dependent GTPase; however, upon binding to guanosine tetraphosphate (ppGpp), the global regulator of stringent response, ObgE exhibits an enhanced interaction with the 50S subunit, resulting in increased equilibrium dissociation of the 70S ribosome into subunits. Furthermore, our cryo-electron microscopy (cryo-EM) structure of the 50S? ObgE? GMPPNP complex indicates that the evolutionarily conserved N-terminal domain (NTD) of ObgE is a tRNA structural mimic, with specific interactions with peptidyl-transferase center, displaying a marked resemblance to Class I release factors. These structural data might define ObgE as a specialized translation factor related to stress responses, and provide a framework towards future elucidation of functional interplay between ObgE and ribosome-associated (p) ppGpp regulators. Together with published data, our results suggest that ObgE might act as a checkpoint in final stages of the 50S subunit assembly under normal growth conditions. And more importantly, ObgE, as a (p) ppGpp effector, might also have a regulatory role in the production of the 50S subunit and its participation in translation under certain stressed conditions. Thus, our findings might have uncovered an under-recognized mechanism of translation control by environmental cues

Chidamide and Decitabine in Combination with a HAG Priming Regimen for Acute Myeloid Leukemia with TP53 Mutation

We analyzed the treatment effects of chidamide and decitabine in combination with a HAG (homoharringtonine, cytarabine, G-CSF) priming regimen (CDHAG) in acute myeloid leukemia (AML) patients with TP53 mutation. Seven TP53 mutated AML patients were treated with CDHAG. The treatment effects were assessed using hemogram detection and bone marrow aspirate. The possible side effects were evaluated based on both hematological and non-hematological toxicity. Four of the seven patients were classified as having achieved complete remission after CDHAG treatment; one patient was considered to have achieved partial remission, and the remaining two patients were considered in non-remission. The overall response rate (ORR) to CDHAG was 71.4%. Regarding the side effects, the hematological toxicity level of the seven patients ranged from level III to level IV, and infections that occurred at lung, blood, and skin were recorded. Nausea, vomiting, liver injury, and kidney injury were also detected. However, all side effects were attenuated by proper management. The CDHAG regimen clearly improved the ORR (71.4%) of TP53-mutated AML patients, with no severe side effects