11 research outputs found
Verbal classes in Somali : allomorphy has no classificatory function
International audienc
Structures of echinomycin, thiocoraline,triostin A, SW-163C, QXC and HQA.
<p>QXC: quinoxaline-2-carboxylic acid; HQA: 3-hydroxyquinaldic acid. Echinomycin and triostin A have QXC as their aromatic precursor during biosynthesis while thiocoraline and SW-163C have HQA as the aromatic precursor.</p
LC-MS analysis of the reaction catalyzed by Qui17.
<p>‘No protein’ represents the sample of negative control lacking Qui17.The reaction was terminated after incubation of 30 min, 60 min, 90 min respectively. The peaks I and II are (2<i>S</i>,3<i>S</i>) β-hydroxytryptophan and (2<i>S</i>,3<i>R</i>) <i>N</i>-formyl-β-hydroxykynurenine. The chemical structure of each compound is shown.</p
LC-MS comparison of echinomycin standard to the fermentation products from wild-type <i>S. griseovariabilis</i> and <i>qui17</i>::<i>aadA</i> mutant.
<p>The peak I is echinomycin; WT: wild-type <i>S. griseovariabilis</i>; ZC1: <i>S. griseovariabilis</i> ZC1 mutant; ECM: echinomycin standard.</p
Q-TOF-MS analysis of the amino acid loading activity of Qui18.
<p>(A) Holo-Qui18 was used as the enzyme, L-tryptophan was tested as substrate; (B) The same as (A) except Qui5 was supplemented (C) Coexpression of Qui5 and holo-Qui18 was used as the enzyme, D-tryptophan was tested as substrate; (D) The same as (C) except the tested substrate was L-phenylalanine; (E) The same as (C) except the tested substrate was L-tryptophan; (F) MS result of the peak I, II and III, which respectively correspond to holo-Qui18, L-tryptophan loaded holo-Qui18 and Qui5; (G) Illustration of the protein molecule corresponding to I, II and III. The molecular weight change from I to II was so small relatively to the molecular weight of I that the retention time for I and II were nearly the same.</p
Organization of echinomycin biosynthetic gene cluster and echinomycin biosynthetic pathway in <i>S. griseovariabilis</i>.
<p>(A) Scheme of the biosynthetic gene cluster of echinomycin in <i>S. griseovariabilis</i>. The transcription direction of each gene was indicated by arrow. <i>qui6</i> and <i>qui7</i> are NRPS genes encoding the NRPS responsible for biosynthesis of the NRP backbone of echinomycin. To clarify the domains contained in Qui6 and Qui7, the scheme of the protein products encoded by <i>qui6</i> and <i>qui7</i> were situated rightly below the corresponding genes. Since the transcription directions of both <i>qui6</i> and <i>qui7</i> were reversed, their protein products were also exhibited inversely. From N terminal to C terminal, the domains contained were C, A, M, T, C, A, M, T, TE in Qui6 and C, A, T, E, C, A, T in Qui7. C: condensation-domain; A: adenylation-domain; T: peptidyl carrier protein-domain; M: methylation-domain; E: epimerase-domain; TE: thioesterase-domain. (B) Echinomycin biosynthetic pathway in <i>S. griseovariabilis</i>. FabC was an ACP engaged in fatty acid biosynthesis and its encoding gene was outside the gene cluster.</p
Proposed biosynthetic pathway for QXC produced by
<p><b><i>S. griseovariabilis</i></b><b>.</b> The biosynthesis of QXC is a part of that of echinomycin. L-Trp: L-tryptophan; L-Trp-S-Qui18: L-tryptophanyl-S-Qui18; (2<i>S</i>,3<i>S</i>) hTrp-S-Qui18: (2<i>S</i>,3<i>S</i>) β-hydroxytryptophanyl-S-Qui18; (2<i>S</i>,3<i>S</i>) hTrp: (2<i>S</i>,3<i>S</i>) β-hydroxytryptophan; (2<i>S</i>,3<i>R</i>) hNFK: (2<i>S</i>,3<i>R</i>) <i>N</i>-formyl-β-hydroxykynurenine; QXC: quinoxaline-2-carboxylic acid.</p
Crystal structure of DndA from <i>Streptomyces lividans</i>.
<p>(<b>A</b>) <b>Overall structure of the DndA dimer.</b> The structure is viewed perpendicular to the two-fold axis of the dimer. The two protomers are shown in magenta and green, respectively. Their bound PLP cofactors are presented as sticks, with carbon atoms yellow, nitrogen atoms blue, oxygen atoms red, and phosphorus atoms orange. (<b>B</b>) <b>Structure of a protomer of DndA.</b> α helices are shown in cyan, β sheets are shown in magenta, and loops are shown in pink. PLP and its covalently linked Lys200 of DndA, as well as the catalytic Cys327 (mutated to serine in our study), are shown in stick representation.</p
Specific activities of WT and point mutants of DndA measured using in vitro cysteine desulfurase activity assay.
<p>Assays were performed for five times, and the average values of specific activities along with standard deviations of the measurements were shown.</p
The binding site of PLP on DndA.
<p>(<b>A</b>) <b>PLP is located in a deep surface pocket on DndA.</b> The two protomers of DndA are shown in surface representation, with only one PLP shown in stick representation. The protomer of DndA harboring this PLP is colored in light grey, whereas the other protomer is colored in dark grey. Blue, red, yellow, and orange represent nitrogen, oxygen, carbon, and phosphorus atoms, respectively. (<b>B</b>) <b>The interaction interface between PLP and DndA.</b> DndA is shown in grey, with carbon atoms of its side chains and PLP shown in green. Blue, red, and orange represent nitrogen, oxygen, and phosphorus atoms, respectively. Hydrogen bonds are represented by magenta dashed lines. The orange circle indicates the presumable location of the carboxylate group of the L-cysteine substrate.</p