Biosynthesis and engineering of the nonribosomal peptides with a C-terminal putrescine.

The broad bioactivities of nonribosomal peptides rely on increasing structural diversity. Genome mining of the Burkholderiales strain Schlegelella brevitalea DSM 7029 leads to the identification of a class of dodecapeptides, glidonins, that feature diverse N-terminal modifications and a uniform putrescine moiety at the C-terminus. The N-terminal diversity originates from the wide substrate selectivity of the initiation module.

The Genomic-Driven Discovery of Glutarimide-Containing Derivatives from .

Glutarimide-containing polyketides exhibiting potent antitumor and antimicrobial activities were encoded via conserved module blocks in various strains that favor the genomic mining of these family compounds. The bioinformatic analysis of the genome of ATCC 10248 showed a silent -AT PKS biosynthetic gene cluster (BGC) on chromosome 2 (Chr2C8), which was predicted to produce new glutarimide-containing derivatives. Then, the silent polyketide synthase gene cluster was successfully activated via in situ promoter insertion and heterologous expression.

Heterologous Biosynthesis of Complex Bacterial Natural Products in .

Bacterial natural products (NPs) are an indispensable source of drugs and biopesticides. Heterologous expression is an essential method for discovering bacterial NPs and the efficient biosynthesis of valuable NPs, but the chassis for Gram-negative bacterial NPs remains inadequate. In this study, we built a mutant Δ::attB by introducing an integrated site () to inactivate the native gladiolin () biosynthetic gene cluster, which stabilizes large foreign gene clusters and reduces the native metabolite profile.

Recombineering enables genome mining of novel siderophores in a non-model strain.

Iron is essential for bacterial survival, and most bacteria capture iron by producing siderophores. bacteria produce various types of bioactive secondary metabolites, such as ornibactin and malleobactin siderophores. In this study, the genome analysis of genomes showed a putative novel siderophore gene cluster , which is highly similar to the ornibactin and malleobactin gene clusters but does not have , a gene encoding a formyltransferase for N-‑hydroxy-ornithine formylation.

Biosynthesis of Glidomides and Elucidation of Different Mechanisms for Formation of β-OH Amino Acid Building Blocks.

Nonribosomal peptide synthetases (NRPSs) can incorporate nonproteinogenic amino acids into peptidyl backbones to increase structural diversity. Genome mining of Schlegelella brevitalea led to the identification of a class of linear lipoheptapeptides, glidomides, featuring two unusual residues: threo-β-OH-L-His and threo-β-OH-D-Asp. The β-hydroxylation of Asp and His is catalyzed by the nonheme Fe /α-ketoglutarate-dependent β-hydroxylases GlmD and GlmF, respectively.

Genomics-Driven Activation of Silent Biosynthetic Gene Clusters in by Screening Recombineering System.

The genus possesses ecological and metabolic diversities. A large number of silent biosynthetic gene clusters (BGCs) in the genome remain uncharacterized and represent a promising resource for new natural product discovery. However, exploitation of the metabolomic potential of is limited by the absence of efficient genetic manipulation tools.

Engineering and elucidation of the lipoinitiation process in nonribosomal peptide biosynthesis.

Nonribosomal peptide synthetases containing starter condensation domains direct the biosynthesis of nonribosomal lipopeptides, which generally exhibit wide bioactivities. The acyl chain has strong impacts on bioactivity and toxicity, but the lack of an in-depth understanding of starter condensation domain-mediated lipoinitiation limits the bioengineering of NRPSs to obtain novel derivatives with desired acyl chains. Here, we show that the acyl chains of the lipopeptides rhizomide, holrhizin, and glidobactin were modified by engineering the starter condensation domain, suggesting a workable approach to change the acyl chain.

Impact of Ultraviolet Radiation on the Aging Properties of SBS-Modified Asphalt Binders.

Styrene Butadiene Styrene (SBS) polymer-modified asphalt binders have become widely used in asphalt pavement because of their advantages in high- and low-temperature performance and fatigue resistance. Asphalt pavement is inevitably exposed to sunlight and ultraviolet (UV) radiation during its construction and service life. However, consideration of the aging effect of UV radiation is still limited in current pavement design and evaluation systems.

Aging Mechanism and Properties of SBS Modified Bitumen under Complex Environmental Conditions.

Bitumen aging can lead to the deterioration of asphalt pavement performance, shortening the service life of road. In order to solve the problem that current studies on the ultraviolet (UV) aging of bitumen either ignore the effects of natural environmental conditions or only consider the effects of water. In this study, different aqueous media and UV coupled simulated aging tests were carried out on virgin bitumen and styrene butadiene styrene (SBS) modified bitumen in a UV environment chamber.