Mikhail A. Belozersky

Bio: Mikhail A. Belozersky is an academic researcher from Moscow State University. The author has contributed to research in topics: Proteolytic enzymes & Protease. The author has an hindex of 23, co-authored 63 publications receiving 1393 citations. Previous affiliations of Mikhail A. Belozersky include Laboratory of Molecular Biology.

Stored proteinases and the initiation of storage protein mobilization in seeds during germination and seedling growth

Abstract: Though endopeptidases and carboxypeptidases are present in protein bodies of dry quiescent seeds the function of these proteases during germination is still a matter of debate. In some plants it was demonstrated that endopeptidases of dry protein bodies degrade storage proteins of these organelles. Other studies describe cases where this did not happen. The role that stored proteinases play in the initiation of storage protein breakdown in germinating seeds thus remains unclear. Numerous reviews state that the initiation of reserve protein mobilization is attributed to de novo formed endopeptidases which together with stored carboxypeptidases degrade the bulk of proteins in storage organs and tissues after seeds have germinated. The evidence that the small amounts of endopeptidases in protein bodies of embryonic axes and cotyledons of dry seeds from dicotyledonous plants play an important role in the initiation of storage protein mobilization during early germination is summarized here.

Diversity of digestive proteinases in Tenebrio molitor (Coleoptera: Tenebrionidae) larvae.

Abstract: The spectrum of Tenebrio molitor larval digestive proteinases was studied in the context of the spatial organization of protein digestion in the midgut. The pH of midgut contents increased from 5.2-5.6 to 7.8-8.2 from the anterior to the posterior. This pH gradient was reflected in the pH optima of the total proteolytic activity, 5.2 in the anterior and 9.0 in the posterior midgut. When measured at the pH and reducing conditions characteristic of each midgut section, 64% of the total proteolytic activity was in the anterior and 36% in the posterior midgut. In the anterior midgut, two-thirds of the total activity was due to cysteine proteinases, whereas the rest was from serine proteinases. In contrast, most (76%) of the proteolytic activity in the posterior midgut was from serine proteinases. Cysteine proteinases from the anterior were represented by a group of anionic fractions with similar electrophoretic mobility. Trypsin-like activity was predominant in the posterior midgut and was due to one cationic and three anionic proteinases. Chymotrypsin-like proteinases also were prominent in the posterior midgut and consisted of one cationic and four anionic proteinases, four with an extended binding site. Latent proteinase activity was detected in each midgut section. These data support a complex system of protein digestion, and the correlation of proteinase activity and pH indicates a physiological mechanism of enzyme regulation in the gut.

Aspartic proteinase from wheat seeds: isolation, properties and action on gliadin.

Abstract: Wheat endosperm was shown to contain an aspartic proteinase capable of hydrolyzing the wheat storage protein, gliadin, in vitro. The enzyme was purified to homogeneity by affinity chromatography on bacilliquin-silochrome, diethylaminoethyl-Toyopearl ion-exchange chromatography, chromatofocusing, and preparative polyacrylamide gel electrophoresis. The sedimentation constant of the enzyme was 3.4 S and the relative molecular mass (Mr), determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, was 58000 dalton (Da). The purified enzyme was completely inhibited by pepstain whereas other enzyme inhibitors did not affect its activity. The enzyme was found to hydrolyze mainly ω- and γ-gliadins with Mr's of 67000–95000 Da, with maximal activity at pH 4.5. The data make it possible to suggest that the enzyme has an endogenous function by initiating proteolysis of storage proteins in germinating wheat seeds.

Protease Inhibitors in Improvement of Plant Resistance to Pathogens and Insects

Abstract: This review concerns the possibility of using plant inhibitors of proteolytic enzymes to improve plant resistance to insects and phytopathogens. The main argument in favor of this approach is that protease inhibitors are widespread in plant tissues and highly active with respect to various proteases of insects, bacteria, and fungi. Genetic engineering yields promising results in the field, as recent studies demonstrate. The main drawbacks of the approach and ways to improve its efficiency are discussed. Still, the approach has several advantages over the standard methods and is ecologically safe.

The genome of the model beetle and pest Tribolium castaneum.

Abstract: Tribolium castaneum is a member of the most species-rich eukaryotic order, a powerful model organism for the study of generalized insect development, and an important pest of stored agricultural products. We describe its genome sequence here. This omnivorous beetle has evolved the ability to interact with a diverse chemical environment, as shown by large expansions in odorant and gustatory receptors, as well as P450 and other detoxification enzymes. Development in Tribolium is more representative of other insects than is Drosophila, a fact reflected in gene content and function. For example, Tribolium has retained more ancestral genes involved in cell-cell communication than Drosophila, some being expressed in the growth zone crucial for axial elongation in short-germ development. Systemic RNA interference in T. castaneum functions differently from that in Caenorhabditis elegans, but nevertheless offers similar power for the elucidation of gene function and identification of targets for selective insect control.

The genome of the model beetle and pest Tribolium castaneum

Abstract: Tribolium castaneum is a member of the most species-rich eukaryotic order, a powerful model organism for the study of generalized insect development, and an important pest of stored agricultural products We describe its genome sequence here This omnivorous beetle has evolved the ability to interact with a diverse chemical environment, as shown by large expansions in odorant and gustatory receptors, as well as P450 and other detoxification enzymes Development in Tribolium is more representative of other insects than is Drosophila, a fact reflected in gene content and function For example, Tribolium has retained more ancestral genes involved in cell-cell communication than Drosophila, some being expressed in the growth zone crucial for axial elongation in short-germ development Systemic RNA interference in T castaneum functions differently from that in Caenorhabditis elegans, but nevertheless offers similar power for the elucidation of gene function and identification of targets for selective insect control

Lifestyle transitions in plant pathogenic Colletotrichum fungi deciphered by genome and transcriptome analyses

Abstract: Colletotrichum species are fungal pathogens that devastate crop plants worldwide. Host infection involves the differentiation of specialized cell types that are associated with penetration, growth inside living host cells (biotrophy) and tissue destruction (necrotrophy). We report here genome and transcriptome analyses of Colletotrichum higginsianum infecting Arabidopsis thaliana and Colletotrichum graminicola infecting maize. Comparative genomics showed that both fungi have large sets of pathogenicity-related genes, but families of genes encoding secreted effectors, pectin-degrading enzymes, secondary metabolism enzymes, transporters and peptidases are expanded in C. higginsianum. Genome-wide expression profiling revealed that these genes are transcribed in successive waves that are linked to pathogenic transitions: effectors and secondary metabolism enzymes are induced before penetration and during biotrophy, whereas most hydrolases and transporters are upregulated later, at the switch to necrotrophy. Our findings show that preinvasion perception of plant-derived signals substantially reprograms fungal gene expression and indicate previously unknown functions for particular fungal cell types.

First off the mark: early seed germination

Abstract: Most plant seeds are dispersed in a dry, mature state. If these seeds are non-dormant and the environmental conditions are favourable, they will pass through the complex process of germination. In this review, recent progress made with state-of-the-art techniques including genome-wide gene expression analyses that provided deeper insight into the early phase of seed germination, which includes imbibition and the subsequent plateau phase of water uptake in which metabolism is reactivated, is summarized. The physiological state of a seed is determined, at least in part, by the stored mRNAs that are translated upon imbibition. Very early upon imbibition massive transcriptome changes occur, which are regulated by ambient temperature, light conditions, and plant hormones. The hormones abscisic acid and gibberellins play a major role in regulating early seed germination. The early germination phase of Arabidopsis thaliana culminates in testa rupture, which is followed by the late germination phase and endosperm rupture. An integrated view on the early phase of seed germination is provided and it is shown that it is characterized by dynamic biomechanical changes together with very early alterations in transcript, protein, and hormone levels that set the stage for the later events. Early seed germination thereby contributes to seed and seedling performance important for plant establishment in the natural and agricultural ecosystem.