Fucosylated Ubiquitin and Orthogonally Glycosylated Mutant A28C: Conceptually New Ligands for Burkholderia Ambifaria Lectin (BambL)†

Ubiquitin as <i>scaffold</i> <i>protein</i> and aryl-α-O-fucoside as determinant to achieve conceptually new ligands with high affinity for <i>Burkholderia ambifaria </i>lectin are described.<div>Ub mutant A28C which displays a Cys residue in addition to the eight Lys residues was expressed. </div><div>The resulting <i>scaffold</i> was orthogonally glycosylated </div><div>to display one thio-rhamnose and up to eight residues of aryl-α-O-fucoside. </div><div>The glycosylated Ub-based scaffolds have unprecedented immune properties.<br></div>

Fucosylated Ubiquitin and Orthogonally Glycosylated Mutant A28C: Conceptually New Ligands for Burkholderia Ambifaria Lectin (BambL)†

Ubiquitin as <i>scaffold</i> <i>protein</i> and aryl-α-O-fucoside as determinant to achieve conceptually new ligands with high affinity for <i>Burkholderia ambifaria </i>lectin are described.<div>Ub mutant A28C which displays a Cys residue in addition to the eight Lys residues was expressed. </div><div>The resulting <i>scaffold</i> was orthogonally glycosylated </div><div>to display one thio-rhamnose and up to eight residues of aryl-α-O-fucoside. </div><div>The glycosylated Ub-based scaffolds have unprecedented immune properties.<br></div>

Synthesis and Antimicrobial Activity of Burkholderia-Related 4-Hydroxy-3-Methyl-2-Alkenylquinolones (HMAQs) and Their N-Oxide Counterparts

ABSTRACT: The Burkholderia genus offers a promising potential in medicine because of the diversity of biologically active natural products encoded in its genome. Some pathogenic Burkholderia spp. biosynthesize a specific class of antimicrobial 2-alkyl-4(1H)-quinolones, i.e., 4-hydroxy-3-methyl-2-alkenylquinolones (HMAQs) and their N-oxide derivatives (HMAQNOs). Herein, we report the synthesis of a series of six HMAQs and HMAQNOs featuring a trans-∆² double bond at the C2-alkyl chain. The quinolone scaffold was obtained via the Conrad-Limpach approach while the (E)-2-alkenyl chain was inserted through Suzuki-Miyaura cross-coupling under microwave radiation without noticeable isomerization according to the optimized conditions. Subsequent oxidation of enolate-protected HMAQs cleanly led to the formation of HMAQNOs following cleavage of the ethyl carbonate group. Synthetic HMAQs and HMAQNOs were in vitro evaluated for their antimicrobial activity against different Gram-negative and Gram-positive bacteria as well as against fungi and yeasts. The biological results support and extend the potential of HMAQs and HMAQNOs as antimicrobials, especially against Gram-positive bacteria. We also confirm the involvement of HMAQs in the autoregulation of the Hmq system in Burkholderia ambifaria.

Synthesis and Antimicrobial Activity of Burkholderia-Related 4-Hydroxy-3-Methyl-2-Alkenylquinolones (HMAQs) and Their N-Oxide Counterparts

ABSTRACT: The Burkholderia genus offers a promising potential in medicine because of the diversity of biologically active natural products encoded in its genome. Some pathogenic Burkholderia spp. biosynthesize a specific class of antimicrobial 2-alkyl-4(1H)-quinolones, i.e., 4-hydroxy-3-methyl-2-alkenylquinolones (HMAQs) and their N-oxide derivatives (HMAQNOs). Herein, we report the synthesis of a series of six HMAQs and HMAQNOs featuring a trans-∆² double bond at the C2-alkyl chain. The quinolone scaffold was obtained via the Conrad-Limpach approach while the (E)-2-alkenyl chain was inserted through Suzuki-Miyaura cross-coupling under microwave radiation without noticeable isomerization according to the optimized conditions. Subsequent oxidation of enolate-protected HMAQs cleanly led to the formation of HMAQNOs following cleavage of the ethyl carbonate group. Synthetic HMAQs and HMAQNOs were in vitro evaluated for their antimicrobial activity against different Gram-negative and Gram-positive bacteria as well as against fungi and yeasts. The biological results support and extend the potential of HMAQs and HMAQNOs as antimicrobials, especially against Gram-positive bacteria. We also confirm the involvement of HMAQs in the autoregulation of the Hmq system in Burkholderia ambifaria.

Exploiting the Natural Diversity of RhlA Acyltransferases for the Synthesis of the Rhamnolipid Precursor 3-(3-Hydroxyalkanoyloxy)Alkanoic Acid

ABSTRACT While rhamnolipids of the Pseudomonas aeruginosa type are commercially available, the natural diversity of rhamnolipids and their origin have barely been investigated. Here, we collected known and identified new rhlA genes encoding the acyltransferase responsible for the synthesis of the lipophilic rhamnolipid precursor 3-(3-hydroxyalkanoyloxy)alkanoic acid (HAA). Generally, all homologs were found in Betaproteobacteria and Gammaproteobacteria. A likely horizontal gene transfer event into Actinobacteria is the only identified exception. The phylogeny of the RhlA homologs from Pseudomonas and Burkholderia species is consistent with the organism phylogeny, and genes involved in rhamnolipid synthesis are located in operons. In contrast, RhlA homologs from the Enterobacterales do not follow the organisms’ phylogeny but form their own branch. Furthermore, in many Enterobacterales and Halomonas from the Oceanospirillales, an isolated rhlA homolog can be found in the genome. The RhlAs from Pseudomonas aeruginosa PA01, Pseudomonas fluorescens LMG 05825, Pantoea ananatis LMG 20103, Burkholderia plantarii PG1, Burkholderia ambifaria LMG 19182, Halomonas sp. strain R57-5, Dickeya dadantii Ech586, and Serratia plymuthica PRI-2C were expressed in Escherichia coli and tested for HAA production. Indeed, except for the Serratia RhlA, HAAs were produced with the engineered strains. A detailed analysis of the produced HAA congeners by high-performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS) highlights the congener specificity of the RhlA proteins. The congener length varies from 4 to 18 carbon atoms, with the main congeners consisting of different combinations of saturated or monounsaturated C10, C12, and C14 fatty acids. The results are discussed in the context of the phylogeny of this unusual enzymatic activity. IMPORTANCE The RhlA specificity explains the observed differences in 3-(3-hydroxyalkanoyloxy)alkanoic acid (HAA) congeners. Whole-cell catalysts can now be designed for the synthesis of different congener mixtures of HAAs and rhamnolipids, thereby contributing to the envisaged synthesis of designer HAAs.

Fucosylated ubiquitin and orthogonally glycosylated mutant A28C: conceptually new ligands for Burkholderia ambifaria lectin (BambL)

Metal free click reactions used to glycosylate ubiquitin and its mutant A28C afforded two protein scaffolds with high affinity for Burkholderia ambifaria lectin (BambL).

Rizobacteria Isolated in the Amazon and Its Influence on the Growth of Guarana Seedlings

Guarana (Paullinia cupana var. Sorbilis (Mart.) Ducke) is a species native from Amazon which has high caffeine concentration. The interactions between guarana and microorganisms in Amazonian soils need to be investigated, especially in relation to the seedling production process, due to its beneficial relationships such as biosynthesis and the supply of stimulating substances, which may result in shortening of the nursery garden or increased productivity. Thus, this research had the objective of evaluating the potential of growth caused by rhizobacteria (Burkholderia ambifaria and Bacillus sp.) in rooting of guarana seedlings. The root length, volume, dry matter of the aerial part, height, number of leaves, leaf area and dry matter of shoot were evaluated at 180 days after planting emergence. Were also determined the carbohydrate and proline content of the aerial part. The rhizobacteria did not influence the growth of the seedlings, however, the carbohydrate contents were higher when the inoculation of the rhizobacteria was carried out with the Burkholderia ambifaria bacteria in the cultivar BRS-Amazonas, with the best results. The proline levels were higher in the control treatment of the two cultivars.