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Journal Issue - Volume 17 Issue 10 (October 2008)

Abstract The genetic code is established by the aminoacylation reactions of aminoacyl tRNA synthetases, where amino acids are matched with triplet anticodons imbedded in the cognate tRNAs. The code established in this way is so robust that it gave birth to the entire tree of life. The tRNA synthetases are organized into two classes, based on their active site architectures. The details of this organization, and other considerations,...

Abstract The trematode Fasciola hepatica (Fa.he.) is a common parasite of human and livestock. The hemoglobin (Hb) of Fa.he., a potential immunogen, was chosen for characterization in the search for an effective vaccine. Characterization of trematode Hbs show that they are intracellular single‐domain globins with the following remarkable features: (1) Fa.he. expresses two Hb isoforms that differ at two amino acid sites (F1: 119Y/123Q; F2: 119F/123L). Both...

Abstract p53 binds to some members of the S100 family (S100B, S100A4, S100A2, and S100A1). We previously showed that both S100B and S100A4 bind to the p53 tetramerization domain, and consequently control its oligomerization state, but only S100B binds to the C‐terminal negative regulatory domain (NRD). Here, we investigate other binding partners for p53 within the S100 family (S100A6 and S100A11), and show that binding to the p53...

Abstract The tumor suppressor p53 can be expressed as different isoforms because of promoter selection and mRNA editing. One isoform, “delta p53” (Δp53), results from what would be an unusual alternative splicing of exons 7/8 of the p53 gene, conserving the reading frame and generating a novel protein with proposed transcriptional activity essential for the intra S‐phase checkpoint. Here, we show that the deletion of the 66 residues...

Abstract FhuA, outer membrane receptor of Escherichia coli, transports hydroxamate‐type siderophores into the periplasm. Cytoplasmic membrane–anchored TonB transduces energy to FhuA to facilitate siderophore transport. Because the N‐terminal cork domain of FhuA occludes the C‐terminal β‐barrel lumen, conformational changes must occur to enable siderophore passage. To localize conformational changes at an early stage of the siderophore ...

Abstract The Medium‐Chain Dehydrogenase/Reductase Engineering Database (MDRED, http://www.mdred.uni‐stuttgart.de) has been established to serve as an analysis tool for a systematic investigation of sequence–structure–function relationships. It includes sequence and structure information of 2684 and 42 medium‐chain dehydrogenases/reductases (MDRs), respectively. Although MDRs are very diverse in sequence, they have a conserved...

Abstract The fibroblast growth factor receptor (FGFR) can be activated through direct interaction with the neural cell adhesion molecule (NCAM). The extracellular part of the FGFR consists of three immunoglobulin‐like (Ig) modules, and that of the NCAM consists of five Ig and two fibronectin type III (F3) modules. NCAM–FGFR interactions are mediated by the third FGFR Ig module and the second NCAM F3 module. Using surface plasmon...

Abstract Bacterial acetyl‐CoA carboxylase is a multifunctional biotin‐dependent enzyme that consists of three separate proteins: biotin carboxylase (BC), biotin carboxyl carrier protein (BCCP), and carboxyltransferase (CT). Acetyl‐CoA carboxylase is a potentially attractive target for novel antibiotics because it catalyzes the first committed step in fatty acid biosynthesis. In the first half‐reaction, BC catalyzes the ATP‐dependent...

Abstract The identification of sequences involved in binding to erythrocytes is an important step for understanding the molecular basis of merozoite–erythrocyte interactions that take place during invasion of the Plasmodium falciparum malaria parasite into host cells. Several molecules located in the apical organelles (micronemes, rhoptry, dense granules) of the invasive‐stage parasite are essential for erythrocyte recognition, invasion, and...

Abstract A covalent dimer of the bacteriophage MS2 coat protein was created by performing genetic fusion of two copies of the gene while removing the stop codon of the first gene. The dimer was crystallized in the cubic F432 space group. The organization of the asymmetric unit together with the F432 symmetry results in an arrangement of subunits that corresponds to T = 3 octahedral particles. The octahedral particles are probably artifacts created by the...

Abstract Expressed protein ligation (EPL) is a protein engineering approach that allows the modification or assembly of a target protein from multiple recombinant and synthetic polypeptides. EPL has been previously used to modify intracellular proteins and small integral membrane proteins for structural and functional studies. Here we describe the semisynthetic site‐specific modification of the complete, multidomain extracellular...

Abstract In the type III secretion system (T3SS) of Aeromonas hydrophila, the putative needle complex subunit AscF requires both putative chaperones AscE and AscG for formation of a ternary complex to avoid premature assembly. Here we report the crystal structure of AscE at 2.7 Å resolution and the mapping of buried regions of AscE, AscG, and AscF in the AscEG and AscEFG complexes using limited protease digestion. The dimeric AscE is comprised ...

Abstract The sodium‐dependent transporters for dopamine, norepinephrine, and serotonin that regulate neurotransmission, also translocate the neurotoxin 1‐methyl‐4‐phenylpyridinium (MPP+). Previous studies implicated residues in transmembrane helix (TMH) XI of DAT as important sites for MPP+ transport. We examined the importance of TMH XI residues F551 and F556 for MPP+ translocation by human SERT. Mutations at hSERT F556, but not F551, reduced both 5‐HT...

Abstract The receptor for activated C‐kinase 1 (RACK1) is a highly conserved WD40 repeat scaffold protein found in a wide range of eukaryotic species from Chlamydymonas to plants and humans. In tissues of higher mammals, RACK1 is ubiquitously expressed and has been implicated in diverse signaling pathways involving neuropathology, cellular stress, protein translation, and developmental processes. RACK1 has established itself as a...

Abstract The three ribosomal proteins L7, S5, and S18 are included in the rare subset of prokaryotic proteins that are known to be Nα‐acetylated. The GCN5‐related N‐acetyltransferase (GNAT) protein RimI, responsible for the Nα‐acetylation of the ribosomal protein S18, was cloned from Salmonella typhimurium LT2 (RimIST), overexpressed, and purified to homogeneity. Steady‐state kinetic parameters for RimIST were determined for AcCoA and a peptide substrate...

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