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The main goal of our research was to search for SSRs in the Eucalyptus EST FORESTs database (using a software for mining SSR-motifs). With this objective, we created a database for cataloging Eucalyptus EST-derived SSRs, and developed a bioinformatics tool, named Satellyptus, for finding and analyzing microsatellites in the Eucalyptus EST database. The search for microsatellites in the FORESTs database containing 71,115 Eucalyptus EST sequences (52.09 Mb) revealed 20,530 SSRs in 15,621 ESTs. The SSR abundance detected on the Eucalyptus ESTs database (29% or one microsatellite every four sequences) is considered very high for plants. Amongst the categories of SSR motifs, the dimeric (37%) and trimeric ones (33%) predominated. The AG/CT motif was the most frequent (35.15%) followed by the trimeric CCG/CGG (12.81%). From a random sample of 1,217 sequences, 343 microsatellites in 265 SSR-containing sequences were identified. Approximately 48% of these ESTs containing microsatellites were homologous to proteins with known biological function. Most of the microsatellites detected in Eucalyptus ESTs were positioned at either the 5’ or 3’ end. Our next priority involves the design of flanking primers for codominant SSR loci, which could lead to the development of a set of microsatellite-based markers suitable for marker-assisted Eucalyptus breeding programs

Background: Selenoprotein biosynthesis requires the interaction of tRNA Sec and specific enzymes that drive the synthesis of selenocysteine. Results: Formation of a molecular complex of selenophosphate synthetase, selenocysteine synthase, and tRNA Sec was identified and characterized. Conclusion:The ternary complex formation is necessary for selenoprotein synthesis.Significance: Our findings demonstrate the formation of a ternary complex and provide a possible scenario for selenium metabolism in bacteria.

Selenium (Se) is an essential trace element for several organisms and is mostly present in proteins as L-selenocysteine (Sec or U). Sec is synthesized on its L-seryl-tRNA to produce Sec-tRNA molecules by a dedicated selenocysteine synthesis machinery and incorporated into selenoproteins at specified in-frame UGA codons. UGA-Sec insertion is signaled by an mRNA stem-loop structure called the SElenoCysteine Insertion Sequence (SECIS). tRNA transcription regulation and folding have been described showing its importance to Sec biosynthesis. Here, we discuss structural aspects of Sec-tRNA and its role in Sec biosynthesis as well as Sec incorporation into selenoproteins. Defects in the Sec biosynthesis or incorporation pathway have been correlated with pathological conditions.

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The hemoflagellate protozoan, Trypanosoma cruzi, mainly transmitted by triatomine insects through blood transfusion or from mother-to-child, causes Chagas' disease. This is a serious parasitic disease that occurs in Latin America, with considerable social and economic impact. Nifurtimox and benznidazole, drugs indicated for treating infected persons, are effective in the acute phase, but poorly effective during the chronic phase. Therefore, it is extremely urgent to find innovative chemotherapeutic agents and/or effective vaccines. Since piplartine has several biological activities, including trypanocidal activity, the present study aimed to evaluate it on two T. cruzi strains proteome. Considerable changes in the expression of some important enzymes involved in parasite protection against oxidative stress, such as tryparedoxin peroxidase (TXNPx) and methionine sulfoxide reductase (MSR) was observed in both strains. These findings suggest that blocking the expression of the two enzymes could be potential targets for therapeutic studies.

Selenophosphate synthetase (SPS) plays an indispensable role in selenium metabolism, being responsible for catalyzing the activation of selenide with adenosine 5 0 -triphosphate (ATP) to generate selenophosphate, the essential selenium donor for selenocysteine synthesis. Recombinant full-length Leishmania major SPS (LmSPS2) was recalcitrant to crystallization. Therefore, a limited proteolysis technique was used and a stable N-terminal truncated construct (ÁN-LmSPS2) yielded suitable crystals. The Trypanosoma brucei SPS orthologue (TbSPS2) was crystallized by the microbatch method using paraffin oil. X-ray diffraction data were collected to resolutions of 1.9 Å for ÁN-LmSPS2 and 3.4 Å for TbSPS2.

Selenocysteine Synthase (SELA, E.C. 2.9.1.1) from Escherichia coli is a homodecamer pyridoxal-5'-phosphate containing enzyme responsible for the conversion of seryl-tRNA(sec) into selenocysteyl-tRNA(sec) in the biosynthesis of the 21th amino acid, selenocysteine (Sec or U). This paper describes the cloning of the E. coli selA gene into a modified pET29a(+) vector and its expression in E. coli strain WL81460, a crucial modification allowing SELA expression without bound endogenous tRNA(sec). This expression strategy enabled the purification and additional biochemical and biophysical characterization of the SELA decamer. The homogeneous SELA protein was obtained using three chromatographic steps. Size Exclusion Chromatography and Native Gel Electrophoresis showed that SELA maintains a decameric state with molecular mass of approximately 500 kDa with an isoelectric point of 6,03. A predominance of α-helix structures was detected by circular dichroism with thermal stability up to 45 °C. The oligomeric assemblage of SELA was investigated by glutaraldehyde crosslinking experiments indicate that SELA homodecameric structure is the result of a stepwise addition of intermediate oligomeric states and not a direct monomer to homodecamer transition. Our results have contributed to the establishment of a robust expression model for the enzyme free of bound RNA and are of general interest to be taken into consideration in all cases of heterologous/homologous expressions of RNA-binding proteins avoiding the carryover of endogenous RNAs, which may interfere with further biochemical characterizations.