Enzymes of Polyphosphate Metabolism in Yeast: Properties, Functions, Practical Significance.

Inorganic polyphosphates (polyP) are the linear polymers of orthophosphoric acid varying in the number of phosphate residues linked by the energy-rich phosphoanhydride bonds. PolyP is an essential component in living cells. Knowledge of polyP metabolizing enzymes in eukaryotes is necessary for understanding molecular mechanisms of polyP metabolism in humans and development of new approaches for treating bone and cardiovascular diseases associated with impaired mineral phosphorus metabolism. Yeast cells represent a rational experimental model for this research due to availability of the methods for studying phosphorus metabolism and construction of knockout mutants and strains overexpressing target proteins. Multicomponent system of polyP metabolism in Saccharomyces cerevisiae cells is presented in this review discussing properties, functioning, and practical significance of the enzymes involved in the synthesis and degradation of this important metabolite.

Lytic peptidase L5 of Lysobacter sp. XL1 with broad antimicrobial spectrum.

The Gram-negative bacterium Lysobacter sp. XL1 secretes lytic enzymes (L1-L5) into the culture medium. Enzyme L5 is the most recently found extracellular lytic enzyme of this bacterium. The paper presents the results of the isolation and characterization of some properties of this enzyme. Thus, enzyme L5 of Lysobacter sp. XL1 is a lytic serine protease. Earlier, the enzyme was shown to be secreted into the culture medium by means of outer membrane vesicles, which possess a lytic effect towards living cells of Erwinia caratovora B15 [Vasilyeva et al., FEBS J 2008;15:3827-3835]. This work shows the action of enzyme L5 either as a vesicle component or the homogeneous enzyme L5 on a broad range of Gram-positive and Gram-negative microorganisms. Moreover, the vesicles containing this enzyme were shown to lyze the selected test cultures more efficiently than the soluble enzyme L5. It appears to be one of the first precedents of a bacteriolytic effect mediated by the action of outer membrane vesicles filled with extracellular lytic enzymes. The results suggest that the enzyme L5 of Lysobacter sp. XL1 and the vesicles containing this enzyme can be used as an antimicrobial drug.