[Functionally Significant Amino Acid Motifs of Heat Shock Proteins: Structural and Bioinformatics Analyses of Hsp60/Hsp10 in Five Classes of Chordata].

The Hsp60/Hsp10 chaperonin system is one of the most studied systems of cell emergency responses to stresses associated with changes in environmental conditions. In this regard, we have performed a bioinformatics analysis of 164 amino acid sequences of Hsp60 and 125 amino acid sequences of Hsp10 in five classes of chordata. This enabled uncovering the relationship between the identity of the amino acid composition of Hsp60/Hsp10 and the evolutionary distance between classes of chordata. In the course of the study of the chaperonin crystal structure, potentially significant amino acid motifs responsible for the oligomerization of Hsp60 and Hsp10 monomers and the association/dissociation of the Hsp60 and Hsp10 heterodimer have been identified. In addition, we have established that Hsp60 and Hsp10 can form amyloid fibrils due to structural features through the alternative using of the oligomerization sites of monomers as well as association/dissociation sites.

The role of laboratory-scale bioreactors at the semi-continuous and continuous microbiological and biotechnological processes.

Laboratory-scale bioreactors represent an important part of microbiological, biotechnological, and biochemical researches. The small volume bioreactors enable the biomass growth, extracellular metabolite production, solid-state fermentation, and biocatalytic processes in a controlled open system. Using the lab-scale bioreactors, the processes which were optimized in experiments can be scaled up to a pilot level. In turn, the manufacturing scale processes can be scaled down to study the heterogeneity of the system and its effect on the producer. This mini-review is focused on a short description of features of the most popular designs of continuous and semi-continuous bioreactors applied at the present time as well as their application area.

[Search for Functionally Significant Motifs and Amino Acid Residues of Actin].

The scientific interest to the structural and functional properties of actin is determined by its abundance in cells. Being an important component of the cytoskeleton, actin is involved in many protein-protein interactions. Using crystal structures and molecular models, we have mapped the amino acid residues that are involved in these interactions and form the ATP-binding site of the actin monomer. Moreover, using mass spectrometry and high-performance liquid chromatography methods, we have discovered the regions of the amino acid sequence of actin that form the core of the actin fibril. According to the bioinformatic analysis, these regions are amyloidogenic and are located in the C-terminal region and in the hinge between the first and third subdomains. The data obtained are applicable to chordate actin, because multiple alignment revealed highly conserved amino acid sequences. In turn, the comparison of the chordate actin with the bacterial homologs showed the presence of numerous amino acid substitutions and insertions.

α-Crystallins Are Small Heat Shock Proteins: Functional and Structural Properties.

During its life cycle, a cell can be subjected to various external negative effects. Many proteins provide cell protection, including small heat shock proteins (sHsp) that have chaperone-like activity. These proteins have several important functions involving prevention of apoptosis and retention of cytoskeletal integrity; also, sHsp take part in the recovery of enzyme activity. The action mechanism of sHsp is based on the binding of hydrophobic regions exposed to the surface of a molten globule. α-Crystallins presented in chordate cells as two αA- and αB-isoforms are the most studied small heat shock proteins. In this review, we describe the main functions of α-crystallins, features of their secondary and tertiary structures, and examples of their partners in protein-protein interactions.