Novel inositol catabolic pathway in Thermotoga maritima

myo‐inositol (MI) is a key sugar alcohol component of various metabolites, e.g. phosphatidylinositol‐based phospholipids that are abundant in animal and plant cells. The seven‐step pathway of MI degradation was previously characterized in various soil bacteria including Bacillus subtilis. Through a combination of bioinformatics and experimental techniques we identified a novel variant of the MI catabolic pathway in the marine hyperthermophilic bacterium Thermotoga maritima. By using in vitro biochemical assays with purified recombinant proteins we characterized four inositol catabolic enzymes encoded in the TM0412–TM0416 chromosomal gene cluster. The novel catabolic pathway in T. maritima starts as the conventional route using the myo‐inositol dehydrogenase IolG followed by three novel reactions. The first 2‐keto‐myo‐inositol intermediate is oxidized by another, previously unknown NAD‐dependent dehydrogenase TM0412 (named IolM), and a yet unidentified product of this reaction is further hydrolysed by TM0413 (IolN) to form 5‐keto‐l ‐gluconate. The fourth step involves epimerization of 5‐keto‐l ‐gluconate to d ‐tagaturonate by TM0416 (IolO). T. maritima is unable to grow on myo‐inositol as a single carbon source. The determined in vitro specificity of the InoEFGK (TM0418–TM0421) transporter to myo‐inositol‐phosphate suggests that the novel pathway in Thermotoga utilizes a phosphorylated derivative of inositol.     

Conformational peculiarities of nuclear protein HMGB1 and specificity of its interaction with DNA

Changes in the secondary structure of DNA and non-histone chromosomal protein HMGB1 were studied by circular dichroism and UV spectroscopy. We have demonstrated that the HMGBI protein is able to change its secondary structure upon binding to DNA. We estimated the proportion of bound protein on the assumption that there were two spectrally distinguishable forms of the HMGB1 in solution. The bound protein fraction decreases with increasing protein to DNA ratios (r) from 0.48 at r = 0.13 to 0.06 at r = 2.43. It has been shown that HMGB1 is able to induce considerable changes in DNA structure even when the amount of the protein directly associated with DNA is low.     

Short-term variations of mycosporine-like amino acids in the carrageenan-producing red macroalga Mazzaella laminarioides (Gigartinales,Rhodophyta) are related to nitrate availability

Journal of Applied Phycology - The effect of solar UV radiation exposure and NO3– supply on mycosporine-like amino acids (MAAs) accumulation in the carrageenan-producing red macroalga...     

Analysis of informativeness of immunohistochemical and flow cytometric methods for estrogen receptor α assessment

Informative capacity analysis of immunohistochemistry (IHC) and flow cytometry (FCM) in the assessment of estrogen receptor α (ERα) expression in breast cancer tissue was performed. Similar frequencies of expression were shown by both methods: 27% of ERα-negative and 73% ERα-positive cases. However, IHC evaluation detected low levels in only 20% of ERα-positive cases, whereas low levels of ERα detected by FCM were 2 times more often (48%). Moreover, FCM revealed positive expression (23–60%) in 33% of IHC ERα-negative cases. Among IHC ER-positive cases, zero ERα expression was detected by FCM in 12.5%. The approaches to minimize errors in routine clinical determination of the estrogen receptor status were proposed.     

Phenomenon of pili formation in Yersinia enterocolitica

In Y. enterocolitica strain, serovar 0:10, the capacity for the formation of pili inducing the mannose-resistant hemagglutination (MRHA) of formolated sheep red blood cells was due to the presence of plasmid pYE10. MRHA-inducing pili differed serologically from Y. pestis and Y. tuberculosis adhesion pili. Plasmid pYE10 was immobilized for transfer to cells of Escherichia coli strain HB101 (rec A) by means of pRP 4. The expression of MRHA-inducing pili in the new host the rec A-independent character of the synthesis. Y. enterocolitica cells containing pYE10 agglutinated in tissue-culture media with 10% of serum added at 37 degrees C.     

Formation of Extracellular Enzyme Systems during the Growth of Geotrichum candidum3C on Cell Walls Isolated from Cereal Grain Coats

The activities of extracellular systems of hemicellulases, pectinases, and cellulases was studied during a 72-h cultivation of Geotrichum candidum3C. The culture was grown on a medium containing 3% cell walls isolated from wheat grain coats, which served as the sole carbon source. Enzymes catalyzing the degradation of pectin substances (beet pectin, -L-arabinan, and 1,4--D-galactan), as well as -D-galactosidase and -L-arabinofuranosidase involved in their hydrolysis, were formed first (4 h after the beginning of cultivation). Enzymes hydrolyzing 4-O-methyl--D-glucurono--D-xylan and sodium carboxymethyl xylan were also found in the culture liquid after 4 h of fungal growth. The contents of pectin-degrading and xylanolytic enzymes reached their maximum levels after 52–56 and 72 h of growth, respectively. Cellulolytic enzymes were detected after 8–28 h of cultivation. Enzymes degrading -D-galacto--D-mannan were found 24 h after the beginning of growth; their content was maximum after 72 h of cultivation.     

Formation of xylitol in Candida guilliermondii 2581 culture

The yeast strain Candida guilliermondii 2581 was chosen for its ability to produce xylitol in media with high concentrations of xylose. The rate of xylitol production at a xylose concentration of 150 g/l is 1.25 g/l per h; the concentration of xylitol after three days of cultivation is 90 g/l; and the relative xylitol yield is 0.6 g per g substrate consumed. The growth conditions were found that resulted in the maximum relative xylitol yield with complete consumption of the sugar: xylose concentration, 150 g/l; pH 6.0; and shaking at 60 rpm. It was shown that the growth under conditions of limited aeration favors the reduction of xylose.