In‐depth and 3‐dimensional exploration of the budding yeast phosphoproteome

Phosphorylation is one of the most dynamic and widespread post‐translational modifications regulating virtually every aspect of eukaryotic cell biology. Here, we assemble a dataset from 75 independent phosphoproteomic experiments performed in our laboratory using Saccharomyces cerevisiae. We report 30,902 phosphosites identified from cells cultured in a range of DNA damage conditions and/or arrested in distinct cell cycle stages. To generate a comprehensive resource for the budding yeast community, we aggregate our dataset with the Saccharomyces Genome Database and another recently published study, resulting in over 46,000 budding yeast phosphosites. With the goal of enhancing the identification of functional phosphorylation events, we perform computational positioning of phosphorylation sites on available 3D protein structures and systematically identify events predicted to regulate protein complex architecture. Results reveal hundreds of phosphorylation sites mapping to or near protein interaction interfaces, many of which result in steric or electrostatic “clashes” predicted to disrupt the interaction. With the advancement of Cryo‐EM and the increasing number of available structures, our approach should help drive the functional and spatial exploration of the phosphoproteome.     

Functional Analysis of B144/LST1: A Gene in the Tumor Necrosis Factor Cluster That Induces Formation of Long Filopodia in Eukaryotic Cells

B144/LST1 is a gene encoded in the human major histocompatibility complex that produces multiple forms of alternatively spliced mRNA and encodes peptides fewer than 100 amino acids in length. B144/LST1 is strongly expressed in dendritic cells. Transfection of B144/LST1 into a variety of cells induces morphologic changes including the production of long, thin filopodia differing from those seen on transfection of a dominant active CDC42 gene. The structures are dynamically rearranging and sometimes connect one cell with another. The full effect of B144/LST1 protein on cell morphology requires the retention of at least one of the four cysteines of the peptide plus the presence of a hydrophobic segment in the protein, but requires only one of the two coding regions present in the terminal 3′ exons.     

Chlorpromazine induced aggregation of normal human hemoglobin. Electron microscopic evidence.

Normal human hemoglobin exceeding a certain minimum concentration (called critical aggregation concentration) undergoes aggregation in presence of the psychotherapeutic drug chlorpromazine (CPZ). The critical aggregation concentration decreases with the increase of CPZ concentration. Electron micrographs of CPZ-treated hemoglobin clearly indicate that the aggregates of hemoglobin are in filamentous form of average width 75 +/- 8 A. A possible mechanism for such aggregation has been discussed.     

In vivo distribution of lithium in plasma and brain

A single administration of LiCl (0.5, 2 and 4 mmol/kg) to adult male albino rats produced a dose dependent increase of Li level in plasma, whole brain and brain regions. The concentration of Li in whole brain and brain regions was much less than that in plasma. Further, it is also found that concentration of Li in plasma reached a peak at 8 hr while that of Li in whole brain and brain regions reached a peak at 12 hr after the administration. The distribution and retention of Li was found to be highest in hypothalamus followed by striatum, pons-medulla, cerebellum and cerebral cortex. Daily administration of LiCl at a dose of 0.5 and 2 mmol/kg/day showed a time and dose dependent increase in plasma Li level up to a period of 21 consecutive days. But at higher dose (4 mmol/kg/day), on the other hand, under similar condition showed a time dependent increase in plasma Li level up to a period of 14 consecutive days and then gradually decreased with prolongation of treatment to 21 consecutive days. In brain there was no such decrease, rather increase in Li level was observed with the prolongation of duration of treatment, highest concentration of Li was found in hypothalamus and striatum than the rest of the brain regions. These results suggest that under short term treatment with LiCl, the clearance rate of Li in brain cell is much slower than that in plasma. Both single and long-term exposure of LiCl produces a dose dependent increase of Li in plasma, whole brain and brain regions.(ABSTRACT TRUNCATED AT 250 WORDS)     

Kinetics of induction and decay of error-prone DNA repair activity in Escherichia coli after treatment with nalidixic acid

Inducible error-prone DNA repair activity was detected by infecting nalidixic acid-pretreated E. coli cells with UV-irradiated phage phi X174. Induction and decay kinetics of reactivation very much resembled that of mutagenesis of the UV-damaged phage. Repair as well as mutagenic activity increased for about 30 min. The maximal error-prone repair capacity, which was induced in the cell during the 30 min nalidixic acid treatment, rapidly died out during subsequent cell growth in absence of nalidixic acid. Induction of this repair mode was not observed in a recA- mutant. In the presence of nalidixic acid plus rifampicin both repair and mutagenic effects were abolished.