Mitochondrial energy-dissipating systems (alternative oxidase, uncoupling proteins, and external NADH dehydrogenase) are involved in development of frost-resistance of winter wheat seedlings.

Gene expression, protein synthesis, and activities of alternative oxidase (AOX), uncoupling proteins (UCP), adenine nucleotide translocator (ANT), and non-coupled NAD(P)H dehydrogenases (NDex, NDPex, and NDin) were studied in shoots of etiolated winter wheat (Triticum aestivum L.) seedlings after exposure to hardening low positive (2°C for 7 days) and freezing (-2°C for 2 days) temperatures. The cold hardening efficiently increased frost-resistance of the seedlings and decreased the generation of reactive oxygen species (ROS) during further cold shock. Functioning of mitochondrial energy-dissipating systems can represent a mechanism responsible for the decrease in ROS under these conditions. These systems are different in their response to the action of the hardening low positive and freezing temperatures. The functioning of the first system causes induction of AOX and UCP synthesis associated with an increase in electron transfer via AOX in the mitochondrial respiratory chain and also with an increase in the sensitivity of mitochondrial non-phosphorylating respiration to linoleic and palmitic acids. The increase in electron transfer via AOX upon exposure of seedlings to hardening freezing temperature is associated with retention of a high activity of NDex. It seems that NDex but not the NDPex and NDin can play an important role in maintaining the functional state of mitochondria in heterotrophic tissues of plants under the influence of freezing temperatures. The involvement of the mitochondrial energy-dissipating systems and their possible physiological role in the adaptation of winter crops to cold and frost are discussed.

[Editing of the mitochondrial cox3 transcript may yield a new site of protein-protein interactions in wild cereal Elymus sibiricus L]. / Redaktirovanie transkripta gena cox3 v mitokhondriiakh dikorastushchego zlaka Elumus sibiricus L. mozhet privodit' k obrazovaniiu novogo uchastka belok-belkovogo vzaimodeistviia.

With PCR, RT-PCR, and direct sequencing, complete nucleotide sequences were established for the Elymus sibiricus mitochondrial cytochrome c oxidase subunit 3 gene (cox3) and its cDNA. The cox3 transcript was shown to have 12 editing sites with changes affecting the amino acid sequence of the protein product. The editing of the primary cox3 transcript was found to change the position of a site of protein-protein interactions. The results demonstrate again the important role of mRNA editing in posttranscriptional regulation of the expression of plant mitochondrial genes.

[RNA editing in different genetic systems]. / Redaktirovanie RNK v razlichnykh geneticheskikh sistemakh.

One of the significant amendments to the central dogma of the molecular biology was the discovery of the RNA editing process in different genetic systems. Whereas other forms of co- and posttranscriptional modifications of messenger RNA (mRNA) (capping, polyadenilation, splicing) retain the correspondence of the primary structure of exon and final transcript, RNA editing disturbs this correspondence changing the primary structure of mRNA after its transcription. The variants of RNA-editing mechanisms are various and include site-specific insertions and deletions of one or several nucleotides (insertion-deletion editing) as well as specific modifications of nucleosides such as C-->U and A-->I deamination or U-->C transamination (conversion editing). These mechanisms differ greatly in different genetic systems but they always result in synthesis of functionally valuable proteins from "incorrect" genes and, correspondingly, can play a significant role in regulation of their expression.

Identification of highly conserved hydrophobic amino acid motif in deduced amino acid sequence of Elymus sibiricus L. mitochondrial S13 ribosomal protein.

The nucleotide sequence of mitochondrial ribosomal protein rps13 gene from wild perennial grass Elymus sibiricus is presented. It was determined by the method of PCR amplification with specific oligonucleotide primers and the direct sequencing of the amplification product. The sequence of E. sibiricus mitochondrial gene for S13 predicts a hydrophobic ribosomal protein of 116 amino acids that shows strong similarity to those of wheat (99.7% identity) and maize (98%). The deduced amino acid sequence of S13 protein from E. sibiricus and homologous plant's (Zea mays, Daucus carota, Nicotiana tabacum, Marchantia polymorpha) and nonplant's (Escherichia coli) proteins shows the presence of hydrophobic amino acids' motif -L-X10-L-X10-M-X10-L-X10-L-. Slightly modified it can be found in many other ribosomal proteins. This conserved motif is presumed to be particularly important for association of the ribosomal S13 protein with other proteins in the small subunit of the mitochondrial ribosome.

[Lytic ability, in relation to gram-positive microorganisms, of a preparation isolated from a Pseudomonas lytica culture]. / Liticheskaia aktivnost' v otnoshenii grampolozhitel'nykh mikroorganizmov fermentnogo preparata, vydelennogo iz kul'tury Pseudmonas lytica.

A lytic enzyme isolated from P. lytica was studied with respect to its effect on pathogenic grampositive and gramnegative organisms. All the grampositive organisms were lyzed by the enzyme to this or that extent. The cells of staphylococci were the most sensitive. The gramnegative organisms were resistant. It was suggested that the lytic enzyme could be used in preparing drugs for treating certain skin diseases caused by pathogenic staphylococci.

[Specificity of hydrolysis of S. aureus 209P cell walls by a lytic preparation of Pseudomonas lytica]. / Issledovanie spetsifichnosti gidroliza kletochnykh stenok S. aureus 209P liticheskim preparatom Pseudomonas lytica.

Specificity of Staphylococcus aureus 209P cell wall hydrolysis by a lytic preparation isolated from the culture liquid filtrate of Pseudomonas lytica VKM V-1454D was studied by the dansylation method. The lytic preparation was found to contain the lytic proteinase lysing the cells of Gram-positive microorganisms. The enzyme hydrolysed the cell walls of S. aureus 209P releasing N-terminal glycine and alanine in amounts of 0.73 and 0.34 mumoles per 1 mumole of lysine, respectively, which indicated the cleavage of the bonds in the pentaglycine bridge and, apparently, of the bond between N-acetylmuramic acid.