[en] Short communication

[en] Short communication

[en] The transcriptional factor Bach1 forms a heterodimer with small Maf family, and functions as a repressor of the Maf recognition element (MARE) in vivo. To investigate the involvement of Bach1 in the heme-dependent regulation of the expression of the α-globin gene, human erythroleukemia K562 cells were cultured with succinylacetone (SA), a heme biosynthetic inhibitor, and the level of α-globin mRNA was examined. A decrease of α-globin mRNA was observed in SA-treated cells, which was restored by the addition of hemin. The heme-dependent expression of α-globin occurred at the transcriptional level since the expression of human α-globin gene promoter-reporter gene containing hypersensitive site-40 (HS-40) was decreased when K562 cells were cultured with SA. Hemin treatment restored the decrease of the promoter activity by SA. The regulation of the HS-40 activity by heme was dependent on the NF-E2/AP-1 (NA) site, which is similar to MARE. The NA site-binding activity of Bach1 in K562 increased upon SA-treatment, and the increase was diminished by the addition of hemin. The transient expression of Bach1 and mutated Bach1 lacking CP motifs suppressed the HS-40 activity, and cancellation of the repressor activity by hemin was observed when wild-type Bach1 was expressed. The expression of NF-E2 strengthened the restoration of the Bach1-effect by hemin. Interestingly, nuclear localization of Bach1 increased when cells were treated with SA, while hemin induced the nuclear export of Bach1. These results indicated that heme plays an important role in the induction of α-globin gene expression through disrupting the interaction of Bach1 and the NA site in HS-40 enhancer in erythroid cells

[en] Highlights: • The crystal structure of CYP116B45 (P450-TT) from T. thermophilus has been solved. • P450-TT crystal structure is the first example of a class VII P450 structure. • P450-TT adopts the typical P450-fold. • Structural deviation of regions involved in substrate recognition is observed. • Analysis of 96 class VII sequences revealed conservation of active site residues. The first crystal structure of a class VII P450, CYP116B46 from Tepidiphilus thermophilus, has been solved at 1.9 Å resolution. The structure reveals overall conservation of the P450-fold and a water conduit around the I-helix. Active site residues have been identified and sequence comparisons have been made with other class VII enzymes. A structure similarity search demonstrated that the P450-TT structure is similar to enzymes capable of oxy-functionalization of fatty acids, terpenes, macrolides, steroids and statins. The insight gained from solving this structure will provide a guideline for future engineering and modelling studies on this catalytically promiscuous class of enzymes.

[en] Expressions appropriate for the evaluation of the hyperfine splitting in ferric-hemoglobin hydroxide have been derived in the Hartree-Fock approximation using ''giant'' multielectron molecular-orbital wave functions formed as linear combinations of atomic orbitals of the constituent atoms and the molecular orbitals of the OH^- complex incorporating overlap effects. Core orbitals as well as valence orbitals have been considered. The relevant multicenter matrix elements have been evaluated accurately by means of the analytical expressions which we have derived by employing a general closed-form expression developed previously for the coefficients of the expansion of a Slater orbital from one center onto the other. Various calculated electric field gradient components have been analyzed separately in terms of the valence and the core orbitals of the central ion (iron) interacting with the orbitals of the other constituent atoms and the complex OH^-. One finds that the ''local'' and ''distant'' parts of the field gradient due to OH^- nearly cancel one another and, consequently, produce negligible effect on the hyperfine splitting of iron. The nitrogens of the porphyrin plane contribute dominantly to the splitting. Other surrounding atoms contribute less and their influence decreases rapidly as their distance from the central ion increases. On combining various contributions, the calculated hyperfine splitting comes out to be 1.44 + 0.16 mm/sec, which agrees excellently with the experimental splitting 1.57 mm/sec observed by Lang and Marshall. The results from the present calculations have been compared with those obtained by Weissbluth and Maling employing semiempirical treatment on a porphyin-hydroxide model compound. Their estimate is found to give negative sign to the splitting in contrast with our result. Sources of disagreement have been pointed out. Positive hyperfine splitting in ferric-hemoglobin compounds is predicted

[en] Recently, several members of a vertebrate protein family containing a six trans-membrane (6TM) domain and involved in apoptosis and cancer (e.g. STEAP, STAMP1, TSAP6), have been identified in Golgi and cytoplasmic membranes. The exact function of these proteins remains unknown. We related this 6TM domain to distant protein families using intermediate sequences and methods of iterative profile sequence similarity search. Here we show for the first time that this 6TM domain is homolog to the 6TM heme binding domain of both the NADPH oxidase (Nox) family and the YedZ family of bacterial oxidoreductases. This finding gives novel insights about the existence of a previously undetected electron transfer system involved in apoptosis and cancer, and suggests further steps in the experimental characterization of these evolutionarily related families

[en] Effects of different levels of soil moisture on growth up to maturity of two cultivars of Pennisetum americanum L. i.e. Tiftlate synthate and IC-8206 were investigated in pots containing sandy clay loam soil. There were four treatments each with six replicates. The survival and appearance of plants was better in response to moderate moisture levels. This shows the sensitivity of the test cultivars to water logging and drought. However, variations were observed in response to these stresses. The cultivars Tiftlate synthate and IC-8206 were found to be truly drought sensitive. Both the cultivars were found to be intermediate in their tolerance to waterlogged conditions. (author)

No abstract available

[en] Positron lifetime experiments have been performed in 50% water/ethyleneglycol with various hemin concentrations at pH 9. Due to the time resolution of the spectrometer, the short lifetimes were not significant separately. We only discussed the long live component ascribed to the orthopositronium annihilation. A critical hemin concentration was observed. We described the annihilation characteristics in relation with the formation of hemin aggregates. An analytical model for positron and positronium chemistry is proposed in terms of interaction with various compounds in the solution, with the reaction rates forming a continuous set within boundaries. (author). 22 refs, 3 figs

[en] To study the relationship amongst leaf chlorophyll contents, yield and related parameters, 18 advanced genotypes of cotton were tested in a trial at Cotton Research Station, Faisalabad. Highly significant results were noticed in the analysis of variance. Further investigation in correlation analysis revealed that there was comendable positive association among leaf chlorophyll contents, seed cotton yield (SCY), No. of sympodia, seed index and boll weight(g). Principal Component Analysis (PCA) demonstrated that only 02 out of 08 PCs showed eigen value greater than 1. The contribution of first two PCs in total variability was 70.77% amongst the genotypes assessed for chlorophyll contents, seed cotton yield and related traits. Remaining six components contributed very less viz. 30.8% in total variability. Valuable positive factor loadings on PC I was attributed by seed cotton yield, chlorophyll contents, boll weight, No. of sympodia, seed index and Ginning out turn (GOT)%. In PC II, maximum positive contribution was presented by plant height whereras maximum negative factor loadings were showed by GOT % and seed index. PCA also confirmed the results of correlation studies by presenting significant positive association among leaf chlorophyll contents, seed cotton yield, No. of sympodia, seed index and boll weight. These results will be helpful in further breeding strategies for selection of genotypes with respect to chlorophyll contents, yield and associated traits. (author)