Analysis of FR901379 Biosynthetic Genes in Coleophoma empetri by Clustered Regularly Interspaced Short Palindromic Repeats/Cas9-Based Genomic Manipulation.

The compound FR901379, a sulfated echinocandin produced by the filamentous fungus Coleophoma empetri F-11899, is an important intermediate for the synthesis of the antifungal drug micafungin. In this study, we established an efficient clustered regularly interspaced short palindromic repeats/Cas9-based gene editing tool for the industrial production strain C. empetri SIPI1284. With this method, the efficiency of gene mutagenesis in the target locus is up to 84%, which enables the rapid gene disruption for the analysis of FR901379 biosynthetic genes. Next, we verified the putative functional genes of the FR901379 biosynthetic gene cluster via gene disruption and gene complementation in vivo. These core functional genes included the nonribosomal peptide synthetase gene (CEnrps), the fatty-acyl-AMP ligase gene (CEligase) responsible for the formation of the activated form of palmitic acid and its transfer to CEnrps, four nonheme mononuclear iron oxygenase genes (CEoxy1, CEoxy2, CEoxy3, and CEoxy4) responsible for the synthesis of nonproteinogenic amino acids, l-homotyrosine biosynthesis genes (CEhtyA-D), two cytochrome P450 enzyme genes (CEp450-1 and CEp450-2), and a transcription regulator gene (CEhyp). In addition, by screening the whole genome, we identified two unknown genes (CEp450-3 and CEsul) responsible for the sulfonyloxy group of FR901379, which were separated from the core FR901379 biosynthetic cluster. Furthermore, during gene disruptions in the research, we obtained a series of FR901379 analogues and elucidated the relationship between the groups and antifungal activities.

CRISPR/Cas9-Based Genome Editing in the Filamentous Fungus Glarea lozoyensis and Its Application in Manipulating gloF.

Glarea lozoyensis is an important industrial fungus that produces the pneumocandin B0, which is used for the synthesis of antifungal drug caspofungin. However, because of the limitations and complications of traditional genetic tools, G. lozoyensis strain engineering has been hindered. In this study, we established an efficient CRISPR/Cas9-based gene editing tool in G. lozoyensis SIPI1208. With this method, gene mutagenesis efficiency in the target locus can be up to 80%, which enables the rapid gene knockout. According to the reports, GloF and Ap-HtyE, proline hydroxylases involved in pneumocandin and Echinocandin B biosynthesis, respectively, can catalyze the proline to generate different ratios of trans-3-hydroxy-l-proline to trans-4-hydroxy-l-proline. Heterologous expression of Ap-HtyE in G. lozoyensis decreased the ratio of pneumocandin C0 to (pneumocandin B0 + pneumocandin C0) from 33.5% to 11% without the addition of proline to the fermentation medium. Furthermore, the gloF was replaced by ap-htyE to study the production of pneumocandin C0. However, the gene replacement has been hampered by traditional gene tools since gloF and gloG, two contiguous genes indispensable in the biosynthesis of pneumocandins, are cotranscribed into one mRNA. With the CRISPR/Cas9 strategy, ap-htyE was knocked in and successfully replaced gloF, and results showed that the knock-in strain retained the ability to produce pneumocandin B0, but the production of pneumocandin C0 was abolished. Thus, this strain displayed a competitive advantage in the industrial production of pneumocandin B0. In summary, this study showed that the CRISPR/Cas9-based gene editing tool is efficient for manipulating genes in G. lozoyensis.

Amentotaxins C-V, Structurally Diverse Diterpenoids from the Leaves and Twigs of the Vulnerable Conifer Amentotaxus argotaenia and Their Cytotoxic Effects.

A phytochemical investigation of the MeOH extract of the leaves and twigs of Amentotaxus argotaenia, a relict vulnerable coniferous species endemic to China, led to the isolation and characterization of 35 diterpenoids/norditerpenoids. Twenty of these are new, including 11 ent-kaurane-type (amentotaxins C-M, 1-11, respectively), three icetexane-type [= 9(10→20)abeo-abietane-type (amentotaxins N-P, 12-14, respectively)], four ent-labdane-type (amentotaxins Q-T, 15-18, respectively), and two isopimarane-type [amentotaxins U (19) and V (20)] compounds. Their structures were elucidated on the basis of spectroscopic data, single-crystal X-ray diffraction, the modified Mosher's method, and electronic circular dichroism data analyses. Compounds 1-9 are rare 18-nor-ent-kaurane-type diterpenoids featuring a 4ß,19-epoxy ring. All the isolates were evaluated for their cytotoxic effects against a small panel of cultured human cancer cell lines (HeLa, A-549, MDA-MB-231, SKOV3, Huh-7, and HCT-116), and some of them exhibited cytotoxicities with IC50 values ranging from 1.5 to 10.0 µM.

Enhancement of A82846B yield and proportion by overexpressing the halogenase gene in Amycolatopsis orientalis SIPI18099.

The glycopeptide antibiotic A82846B (chloroeremomycin) produced by Amycolatopsis orientalis is the precursor of the semi-synthetic antibiotic oritavancin. However, during the industrial production of A82846B, two major impurities, A82846A (63.6%) and A82846C (12%) which are structurally similar to A82846B (24.4%), are also produced. In this study, to improve the ratio of A82846B to A and C, the genes encoding halogenase in A82846B and vancomycin synthesis were integrated into A. orientalis SIPI18099 to test their halogenation ability, respectively. The results indicated that chal from the A82846B biosynthesis pathway was more efficient in reducing A and C factors. Moreover, by increasing the chal copy number, the proportion of A and C were gradually reduced while the titer and proportion of A82846B were improved. In a scaled-up industrial process, the proportion of A and C were decreased to 11.6% and 0.2% in the recombinant strain A.orientalis chal-3 with three gene copies of chal and the titers of A82846B (2.2 g/L) has increased by 2.8-folds compared to 780 mg/L produced by the parental strain, suggesting that the recombinant strain was suitable for the industrial production of A82846B with lower impurities.

[Screening of strain producing an novel esterase with high enantioselectivity and molecular cloning of the enzyme gene].

A novel strain producing an enantioselective lipolytic enzyme was isolated from soil samples, and identified as Pseudomonas putida NH33. A genomic library of P. putida NH33 was constructed and screened for esterase activity in E. coli. One positive clone was isolated, and subsequent analyses of the plasmid by restriction mapping revealed a 4.7kb DNA fragment carrying esterase gene. The nucleotide sequence of the DNA was found to contain an open reading frame of 1142 nucleotides encoding esterase of 381 amino acid residues and designated PPEst. The primary structure of the esterase exhibited 35%-40% homology to those of related enzymes from various sources and 80%-90% homology to esterases from the genus Pseudomonas. Amino acid sequence deduced from the nucleotide sequence contains of the consensus active site sequence, GXSXG, of serine esterase. The PPEst fragments were cloned into the expression vector pET-22b( + ) and transformed into E. coli BL21 (DE3), and the recombinant protein fused with 6 x His at its C-terminus was purified to homogeneity by a single immobilized metal ion affinity chromatographic step. The molecular mass of the esterase was determined to be approximately 42kDa by SDS-PAGE. The purified enzyme could convert ethyl esters of 2-arylpropanoic acid to S-isomer of 2-arylpropanoic acids with an optical purity of > 99%. The result suggests that this esterase is excellent biocatalyst for synthesis of chiral pharmaceuticals. The enzyme is an novel esterase, and its nucleotide sequence has been submitted to GenBank under accession number AY896293.