Conservation and divergence of the G-interfaces of Drosophila melanogaster septins.

Septins possess a conserved guanine nucleotide-binding (G) domain that participates in the stabilization of organized hetero-oligomeric complexes which assemble into filaments, rings and network-like structures. The fruit fly, Drosophila melanogaster, has five such septin genes encoding Sep1, Sep2, Sep4, Sep5 and Pnut. Here, we report the crystal structure of the heterodimer formed between the G-domains of Sep1 and Sep2, the first from an insect to be described to date.

SAXSMoW 3.0: New advances in the determination of the molecular weight of proteins in dilute solutions from SAXS intensity data on a relative scale.

SAXSMoW (SAXS Molecular Weight) is an online platform widely used over the past few years for determination of molecular weights of proteins in dilute solutions. The scattering intensity retrieved from small-angle X-ray scattering (SAXS) raw data is the sole input to SAXSMoW for determination of molecular weights of proteins in liquid. The current updated SAXSMoW version 3.

The Specific Elongation Factor to Selenocysteine Incorporation in Escherichia coli: Unique tRNA Recognition and its Interactions.

Several molecular mechanisms are involved in the genetic code interpretation during translation, as codon degeneration for the incorporation of rare amino acids. One mechanism that stands out is selenocysteine (Sec), which requires a specific biosynthesis and incorporation pathway. In Bacteria, the Sec biosynthesis pathway has unique features compared with the eukaryote pathway as Ser to Sec conversion mechanism is accomplished by a homodecameric enzyme (selenocysteine synthase, SelA) followed by the action of an elongation factor (SelB) responsible for delivering the mature Sec-tRNA into the ribosome by the interaction with the Selenocysteine Insertion Sequence (SECIS).

Seryl-tRNA synthetase specificity for tRNA in Bacterial Sec biosynthesis.

tRNA synthetases are responsible for decoding the molecular information, from codons to amino acids. Seryl-tRNA synthetase (SerRS), besides the five isoacceptors of tRNA, recognizes tRNA for the incorporation of selenocysteine (Sec, U) into selenoproteins. The selenocysteine synthesis pathway is known and is dependent on several protein-protein and protein-RNA interactions.

Characterization of a Schistosoma mansoni NDPK expressed in sexual and digestive organs.

Nucleoside diphosphate kinases (NDPKs) are crucial to keep the high triphosphate nucleotide levels in the biological process. The enzymatic mechanism has been extensively described; however, the structural characteristics and kinetic parameters have never been fully determined. In Schistosoma mansoni, NDPK (SmNDPK) is directly involved in the pyrimidine and purine salvage pathways, being essential for nucleotide metabolism.

In vitro and in vivo characterization of the multiple isoforms of Schistosoma mansoni hypoxanthine-guanine phosphoribosyltransferases.

Schistosoma mansoni, the parasite responsible for schistosomiasis, lacks the "de novo" purine biosynthetic pathway and depends entirely on the purine salvage pathway for the supply of purines. Numerous reports of praziquantel resistance have been described, as well as stimulated efforts to develop new drugs against schistosomiasis. Hypoxanthine-guanine phosphoribosyltransferase (HGPRT) is a key enzyme of the purine salvage pathway.

The unique tRNA and its role in selenocysteine biosynthesis.

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).