Effect of Biotin Starvation on Gene Expression in Komagataella phaffii Cells.

Methylotrophic yeast Komagataella phaffii is widely used in biotechnology for recombinant protein production. Due to the practical significance of these yeasts, it is extremely important to properly select cultivation conditions and optimize the media composition. In this study the effect of biotin starvation on gene expression in K. phaffii at transcriptome level was investigated. It was demonstrated, that the response of K. phaffii cell to biotin deficiency strongly depends on the carbon source in the medium. In the media containing glycerol, biotin deficiency led to activation of the genes involved in biotin metabolism, glyoxylate cycle, and synthesis of acetyl-CoA in cytoplasm, as well as repression of the genes, involved in lipo- and gluconeogenesis. In the methanol-containing media, biotin deficiency primarily led to repression of the genes, involved in protein synthesis, and activation of cell response to oxidative stress.

Between Adamantane and Atrane: Intrabridgehead Interactions in the Cage-Like Phosphane Related to a Novel Tris(homoadamantane) Ring System.

Herein, we report unusual four-center interactions in the novel cage-like phosphane, 1,4,7-triaza-9-phosphatricyclo[5.3.2.1(4,9) ]tridecane (CAP). This water-soluble ligand, the first example of a tris(homoadamantane) ring system, can be considered a macrocyclic homologue of the well-known PTA (1,3,5-triaza-7-phosphaadamantane). However, (31) P NMR spectroscopic anomalies of CAP follow those typical for the bi-/tricyclic atrane systems. Another atrane-like feature of CAP is the ability of one nitrogen atom to undergo out-in pyramidal inversion. The latter is associated with a substantial decrease in the intracage N-N and P-N distances. Analysis of electron density distribution [molecular electrostatic potential (MESP) and atoms-in-molecules (AIM) approaches] suggests that the P and N atoms in the pyramidally inverted CAP derivatives are involved in interactions resulting in accumulation of electron density at the center of the phosphane cage. The latter can reliably explain the stereoelectronic and NMR anomalies of the new ligand. The semi-flexible CAP cage populates the structural niche between the rigid adamantine skeleton of PTA and flexible atrane systems and can be regarded as an alternative to PTA in aqueous coordination chemistry.

Acid phosphatases of budding yeast as a model of choice for transcription regulation research.

Acid phosphatases of budding yeast have been studied for more than forty years. This paper covers biochemical characteristics of acid phosphatases and different aspects in expression regulation of eukaryotic genes, which were researched using acid phosphatases model. A special focus is devoted to cyclin-dependent kinase Pho85p, a negative transcriptional regulator, and its role in maintaining mitochondrial genome stability and to pleiotropic effects of pho85 mutations.