Discovery of Novel Chemical Series of OXA-48 β-Lactamase Inhibitors by High-Throughput Screening.

The major cause of bacterial resistance to β-lactams is the production of hydrolytic β-lactamase enzymes. Nowadays, the combination of β-lactam antibiotics with β-lactamase inhibitors (BLIs) is the main strategy for overcoming such issues. Nevertheless, particularly challenging β-lactamases, such as OXA-48, pose the need for novel and effective treatments.

Caffeine extends yeast lifespan by targeting TORC1.

Dietary nutrient limitation (dietary restriction) is known to increase lifespan in a variety of organisms. Although the molecular events that couple dietary restriction to increased lifespan are not clear, studies of the model eukaryote Saccharomyces cerevisiae have implicated several nutrient-sensitive kinases, including the target of rapamycin complex 1 (TORC1), Sch9, protein kinase A (PKA) and Rim15. We have recently demonstrated that TORC1 activates Sch9 by direct phosphorylation.

Sch9 is a major target of TORC1 in Saccharomyces cerevisiae.

The Target of Rapamycin (TOR) protein is a Ser/Thr kinase that functions in two distinct multiprotein complexes: TORC1 and TORC2. These conserved complexes regulate many different aspects of cell growth in response to intracellular and extracellular cues. Here we report that the AGC kinase Sch9 is a substrate of yeast TORC1.

Rim15 and the crossroads of nutrient signalling pathways in Saccharomyces cerevisiae.

In recent years, the general understanding of nutrient sensing and signalling, as well as the knowledge about responses triggered by altered nutrient availability have greatly advanced. While initial studies were directed to top-down elucidation of single nutrient-induced pathways, recent investigations place the individual signalling pathways into signalling networks and pursue the identification of converging effector branches that orchestrate the dynamical responses to nutritional cues. In this review, we focus on Rim15, a protein kinase required in yeast for the proper entry into stationary phase (G0).

Regulation of G0 entry by the Pho80-Pho85 cyclin-CDK complex.

Eukaryotic cell proliferation is controlled by growth factors and essential nutrients. In their absence, cells may enter into a quiescent state (G0). In Saccharomyces cerevisiae, the conserved protein kinase A (PKA) and rapamycin-sensitive TOR (TORC1) pathways antagonize G0 entry in response to carbon and/or nitrogen availability primarily by inhibiting the PAS kinase Rim15 function.

A platform for high-throughput expression of recombinant human enzymes secreted by insect cells.

Functional genomics and proteomics have been fields of intense investigation, since the disclosure of the sequence of the human genome. To contribute to the assignment of a physiological role to the vast number of coding genes with unknown function, we have undertaken a program to clone, express, purify and determine the catalytic activity of those enzymes predicted to enter the secretory pathway, focusing our efforts on human peptidases. Our strategy to promote high-throughput expression and purification of recombinant proteins secreted by insect cells relies on the expression of the target enzymes with their native leader sequences and on the carboxyl-terminal fusion with a poly-histidine tag.

A cell sizer network involving Cln3 and Far1 controls entrance into S phase in the mitotic cycle of budding yeast.

Saccharomyces cerevisiae must reach a carbon source-modulated critical cell size, protein content per cell at the onset of DNA replication (Ps), in order to enter S phase. Cells grown in glucose are larger than cells grown in ethanol. Here, we show that an increased level of the cyclin-dependent inhibitor Far1 increases cell size, whereas far1 Delta cells start bud emergence and DNA replication at a smaller size than wild type.

TOR and PKA signaling pathways converge on the protein kinase Rim15 to control entry into G0.

The highly conserved Tor kinases (TOR) and the protein kinase A (PKA) pathway regulate cell proliferation in response to growth factors and/or nutrients. In Saccharomyces cerevisiae, loss of either TOR or PKA causes cells to arrest growth early in G(1) and to enter G(0) by mechanisms that are poorly understood. Here we demonstrate that the protein kinase Rim15 is required for entry into G(0) following inactivation of TOR and/or PKA.

Checking cell size in budding yeast: a systems biology approach.

The regulation of cell cycle progression via the attainment of a critical cell size is a conserved feature from simpler unicellular organisms to mammalian cells that is obtaining much attention recently. Genome wide analysis of Saccharomyces cerevisiae deletion strains, genetic epistasis, DNA microarray analysis have recently revealed an increasingly complex network of cell size modulation mechanisms. A systems biology-based approach, that is needed to structure the underlying complexity of cell cycle regulatory mechanisms, is described.