Synthesis and biological evaluation of coprinoferrin, an acylated tripeptide hydroxamate siderophore

Coprinoferrin (CPF), originally isolated from a genetically engineered strain (ΔlaeA) of the mushroom fungus Coprinopsis cinerea, is an acylated tripeptide hydroxamate consisting of tandem aligned N5-hexanoyl-N5-hydroxy-L-ornithine with modifications of N-acetyl and C-carboxamide. These unique chemical properties make CPF an iron(III) binder (siderophore), which helps in iron acquisition from the environment and promotes hyphal growth as well as fruiting body formation in C. cinerea. However, CPF's detailed mode of action remains enigmatic. In this study, we have accomplished the synthesis of CPF from N-Boc-L-glutamic acid 5-benzyl ester. The physicochemical characteristics, spectroscopic features, and biological activity observed in the synthetic CPF closely match those of natural CPF. This alignment provides unequivocal confirmation of the proposed chemical structure, facilitating a deeper understanding of its physiological role in nature, particularly in fruiting body formation.

Association between physical activity and the prevalence of tumorigenic bacteria in the gut microbiota of Japanese adults: a cross-sectional study

Escherichia coli harboring polyketide synthase (pks+ E. coli) has been suggested to contribute to colorectal cancer development. Physical activity is strongly associated with lower colorectal cancer risks, but its effects on pks+ E. coli remain unclear. The aim of this study was to investigate the association between pks+ E. coli prevalence and physical activity. A cross-sectional study was conducted on 222 Japanese adults (27-79-years-old, 73.9% female). Triaxial accelerometers were used to measure light-intensity physical activity, moderate-to-vigorous intensity physical activity, the physical activity level, step-count, and time spent inactive. Fecal samples collected from participants were used to determine the prevalence of pks+ E. coli. Multivariate logistic regression analysis and restricted cubic spline curves were used to examine the association between pks+ E. coli prevalence and physical activity. The prevalence of pks+ E. coli was 26.6% (59/222 participants). The adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for the highest tertile with reference to the lowest tertile of physical activity variables were as follows: light-intensity physical activity (OR 0.63; 95% CI 0.26-1.5), moderate-to-vigorous intensity physical activity (OR 0.85; 95% CI 0.39-1.87), physical activity level (OR 0.69; 95% CI 0.32-1.51), step-count (OR 0.92; 95% CI 0.42-2.00) and time spent inactive (OR 1.30; 95% CI 0.58-2.93). No significant dose-response relationship was found between all physical activity variables and pks+ E. coli prevalence. Our findings did not suggest that physical activity has beneficial effects on the prevalence of pks+ E. coli. Longitudinal studies targeting a large population are needed to clarify this association.

Non-target GC-MS analyses of fecal VOCs in NASH-hepatocellular carcinoma model STAM mice

The increased incidence of obesity in the global population has increased the risk of several chronic inflammation-related diseases, including non-alcoholic steatohepatitis (NASH)-hepatocellular carcinoma (HCC). The progression from NASH to HCC involves a virus-independent liver carcinogenic mechanism; however, we currently lack effective treatment and prevention strategies. Several reports have suggested that fecal volatile organic compounds (VOCs) are strongly associated with NASH-HCC; therefore, we explored the biomarkers involved in its pathogenesis and progression. Fecal samples collected from control and NASH-HCC model STAM mice were subjected to headspace autosampler gas chromatography-electron ionization-mass spectrometry. Non-target profiling analysis identified diacetyl (2,3-butandione) as a fecal VOC that characterizes STAM mice. Although fecal diacetyl levels were correlated with the HCC in STAM mice, diacetyl is known as a cytotoxic/tissue-damaging compound rather than genotoxic or mutagenic; therefore, we examined the effect of bioactivity associated with NASH progression. We observed that diacetyl induced several pro-inflammatory molecules, including tumor necrosis factor-α, cyclooxygenase-2, monocyte chemoattractant protein-1, and transforming growth factor-β, in mouse macrophage RAW264.7 and Kupffer KPU5 cells. Additionally, we observed that diacetyl induced α-smooth muscle actin, one of the hallmarks of fibrosis, in an ex vivo cultured hepatic section, but not in in vitro hepatic stellate TWNT-1 cells. These results suggest that diacetyl would be a potential biomarker of fecal VOC in STAM mice, and its ability to trigger the macrophage-derived inflammation and fibrosis may partly contribute to NASH-HCC carcinogenesis.

Biosynthetic Gene Expression and Tissue Distribution of Diosgenin in Dioscorea japonica

Diosgenin is an aglycone of dioscin, a major bioactive steroidal saponin found in plants, including Himalayan Paris (Paris polyphylla), fenugreek (Trigonella foenum-graecum), and yam (Dioscorea spp.). We have previously demonstrated that a species of natural yam, Dioscorea japonica, contains a promising bioactive compound diosgenin, which induces anti-carcinogenic and anti-hypertriacylglycerolemic activities. Here, we found for the first time that Japanese yam (D. japonica) bulbils are richer in diosgenin than the edible tubers (rhizomes) and leaves. LC-MS and imaging-MS analyses revealed that diosgenin accumulated in the peripheral region of D. japonica bulbils. Additionally, we performed RNA-seq analysis of D. japonica, and multiple sequence alignment identified D. japonica CYP90 (DjCYP90), the orthologous gene of CYP90G4 in P. polyphylla, CYP90B50 in T. foenum-graecum, CYP90G6 in Dioscorea zingiberensis, and CYP90G in Dioscorea villosa, which encodes a diosgenin biosynthetic rate-limiting enzyme. The expression levels of DjCYP90 were significantly upregulated in D. japonica bulbils than in its rhizomes and leaves. Since diosgenin is one of the most promising functional food factors executing several favorable bioactivities, D. japonica bulbils rich in diosgenin would be a beneficial natural resource.

1,2,3-Triazine formation mechanism of the fairy chemical 2-azahypoxanthine in the fairy ring-forming fungus Lepista sordida

2-Azahypoxanthine (AHX) was first isolated from the culture broth of the fungus Lepista sordida as a fairy ring-inducing compound. It has since been found that a large number of plants and mushrooms produce AHX endogenously and that AHX has beneficial effects on plant growth. The AHX molecule has an unusual, nitrogen-rich 1,2,3-triazine moiety of unknown biosynthetic origin. Here, we establish the biosynthetic pathway for AHX formation in L. sordida. Our results reveal that the key nitrogen sources that are responsible for the 1,2,3-triazine formation are reactive nitrogen species (RNS), which are derived from nitric oxide (NO) produced by NO synthase (NOS). Furthermore, RNS are also involved in the biochemical conversion of 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranosyl 5'-monophosphate (AICAR) to AHX-ribotide (AHXR), suggesting that a novel biosynthetic route that produces AHX exists in the fungus. These findings demonstrate a physiological role for NOS in AHX biosynthesis as well as in biosynthesis of other natural products containing a nitrogen-nitrogen bond.

Induction of DNA Damage in Mouse Colorectum by Administration of Colibactin-producing Escherichia coli, Isolated from a Patient With Colorectal Cancer

BACKGROUND/AIM

Among colorectal cancer-associated intestinal microbiota, colibactin-producing (clb⁺) bacteria are attracting attention. We aimed to clarify the interaction between clb⁺ Escherichia coli and normal colorectal epithelial cells in vivo and in vitro.

MATERIALS AND METHODS

Five-week-old female Balb/c mice were divided in an untreated group, a group treated with clb⁺ E. coli isolated from a Japanese patient with colorectal cancer (E. coli-50), and a group treated with non colibactin-producing E. coli (E. coli-50/ΔclbP). Mice were sacrificed at 18 weeks of treatment.

RESULTS

Treatment with clb⁺ E. coli increased positivity for H2A histone family member X phosphorylated at Ser-139 (γH2AX) in epithelial cells of the luminal surface of the mouse rectum but this did not occur in the E. coli-50/ΔclbP and untreated groups. In an in vitro setting, the ratio of apoptotic cells was increased and cell counts were reduced by treatment with clb⁺ E. coli more than in untreated cells and normal rat colorectal epithelial cells.

CONCLUSION

E. coli-50 induced DNA damage in the mouse rectum, possibly by direct interaction between clb⁺ E. coli and normal colorectal epithelial cells. Our findings imply that regulation of clb⁺ E. coli infection may be a useful strategy for colorectal cancer control.

Toward Engineered Biosynthesis of Drugs in Human Cells

Biosynthetic genes are not only responsible for the formation of bioactive substances but also suited for other applications including gene therapy. To test the feasibility of human cells producing antibiotics in situ when provided with a heterologous biosynthetic gene, we focused on cytochrome P450, the class of enzymes important in conferring bioactivity to natural product precursors. We selected Fma-P450 that plays a central role in the fumagillin antimicrobial biosynthesis in Aspergillus fumigatus to examine fungal metabolite production by HeLa cells that express fma-P450 heterologously. Here we show that HeLa cells harboring fma-P450 can biosynthesize 5-hydroxyl-β-trans-bergamoten and cytotoxic 5-epi-demethoxyfumagillol when supplemented with the nontoxic precursor β-trans-bergamotene. While the production level was insufficient to effect cell death, we demonstrate that programming human cells to autogenerate antibiotics by introducing a heterologous biosynthetic gene is feasible.

Association of Escherichia coli containing polyketide synthase in the gut microbiota with colorectal neoplasia in Japan

Escherichia coli containing polyketide synthase in the gut microbiota (pks⁺ E coli) produce a polyketide-peptide genotoxin, colibactin, and are suspected to play a role in the development of colorectal neoplasia. To clarify the role of pks⁺ E coli in the early stage of tumorigenesis, we investigated whether the pks status of E coli was associated with the prevalence of colorectal neoplasia. This cross-sectional analysis of data from a prospective cohort in Izu Oshima, Japan included asymptomatic residents aged 40-79 years who underwent screening colonoscopy and provided a stool sample. We identified 543 participants with colorectal neoplasia (22 colorectal cancer and 521 adenoma) as cases and 425 participants with normal colon as controls. The pks status of E coli was assayed using stool DNA and specific primers that detected pks⁺ E coli. The proportion of pks⁺ E coli was 32.6% among cases and 30.8% among controls. Compared with those with pks^- E coli, the odds ratio (OR) (95% confidence interval) for participants with pks⁺ E coli was 1.04 (0.77-1.41) after adjusting for potential confounders. No statistically significant associations were observed regardless of tumor site or number of colorectal adenoma lesions. However, stratified analyses revealed increased ORs among participants who consumed cereals over the median intake or vegetables under the median intake. Overall, we found no statistically significant association between pks⁺ E coli and the prevalence of colorectal adenoma lesions among this Japanese cohort. However, positive associations were suggested under certain intake levels of cereals or vegetables.

Mother-to-infant transmission of the carcinogenic colibactin-producing bacteria

BACKGROUND

The Escherichia coli strain that is known to produce the genotoxic secondary metabolite colibactin is linked to colorectal oncogenesis. Therefore, understanding the properties of such colibactin-positive E. coli and the molecular mechanism of oncogenesis by colibactin may provide us with opportunities for early diagnosis or prevention of colorectal oncogenesis. While there have been major advances in the characterization of colibactin-positive E. coli and the toxin it produces, the infection route of the clb + strain remains poorly characterized.

RESULTS

We examined infants and their treatments during and post-birth periods to examine potential transmission of colibactin-positive E. coli to infants. Here, analysis of fecal samples of infants over the first month of birth for the presence of a colibactin biosynthetic gene revealed that the bacterium may be transmitted from mother to infant through intimate contacts, such as natural childbirth and breastfeeding, but not through food intake.

CONCLUSIONS

Our finding suggests that transmission of colibactin-positive E. coli appears to be occurring at the very early stage of life of the newborn and hints at the possibility of developing early preventive measures against colorectal cancer.

Stool pattern is associated with not only the prevalence of tumorigenic bacteria isolated from fecal matter but also plasma and fecal fatty acids in healthy Japanese adults

BACKGROUND

Colibactin-producing Escherichia coli containing polyketide synthase (pks⁺ E. coli) has been shown to be involved in colorectal cancer (CRC) development through gut microbiota analysis in animal models. Stool status has been associated with potentially adverse gut microbiome profiles from fecal analysis in adults. We examined the association between stool patterns and the prevalence of pks⁺ E. coli isolated from microbiota in fecal samples of 224 healthy Japanese individuals.

RESULTS

Stool patterns were determined through factorial analysis using a previously validated questionnaire that included stool frequency, volume, color, shape, and odor. Factor scores were classified into tertiles. The prevalence of pks⁺ E. coli was determined by using specific primers for pks⁺ E. coli in fecal samples. Plasma and fecal fatty acids were measured via gas chromatography-mass spectrometry. The prevalence of pks⁺ E. coli was 26.8%. Three stool patterns identified by factorial analysis accounted for 70.1% of all patterns seen (factor 1: lower frequency, darker color, and harder shape; factor 2: higher volume and softer shape; and factor 3: darker color and stronger odor). Multivariable-adjusted odds ratios (95% confidence intervals) of the prevalence of pks⁺ E. coli for the highest versus the lowest third of the factor 1 score was 3.16 (1.38 to 7.24; P for trend = 0.006). This stool pattern exhibited a significant positive correlation with fecal isobutyrate, isovalerate, valerate, and hexanoate but showed a significant negative correlation with plasma eicosenoic acid and α-linoleic acid, as well as fecal propionate and succinate. No other stool patterns were significant.

CONCLUSIONS

These results suggest that stool patterns may be useful in the evaluation of the presence of tumorigenic bacteria and fecal fatty acids through self-monitoring of stool status without the requirement for specialist technology or skill. Furthermore, it may provide valuable insight about effective strategies for the early discovery of CRC.

Isolation of New Colibactin Metabolites from Wild-Type Escherichia coli and In Situ Trapping of a Mature Colibactin Derivative

Colibactin is a polyketide-nonribosomal peptide hybrid secondary metabolite that can form interstrand cross-links in double-stranded DNA. Colibactin-producing Escherichia coli has also been linked to colorectal oncogenesis. Thus, there is a strong interest in understanding the role colibactin may play in oncogenesis. Here, using the high-colibactin-producing wild-type E. coli strain we isolated from a clinical sample with the activity-based fluorescent probe we developed earlier, we were able to identify colibactin 770, which was recently identified and proposed as the complete form of colibactin, along with colibactin 788, 406, 416, 420, and 430 derived from colibactin 770 through structural rearrangements and solvolysis. Furthermore, we were able to trap the degrading mature colibactin species by converting the diketone moiety into quinoxaline in situ in the crude culture extract to form colibactin 860 at milligram scale. This allowed us to determine the stereochemically complex structure of the rearranged form of an intact colibactin, colibactin 788, in detail. Furthermore, our study suggested that we were capturing only a few percent of the actual colibactin produced by the microbe, providing a crude quantitative insight into the inherent instability of this compound. Through the structural assignment of colibactins and their degradative products by the combination of LC-HRMS and NMR spectroscopies, we were able to elucidate further the fate of inherently unstable colibactin, which could help acquire a more complete picture of colibactin metabolism and identify key DNA adducts and biomarkers for diagnosing colorectal cancer.

o-Anisidine Dimer, 2-Methoxy-N4-(2-methoxyphenyl) Benzene-1,4-diamine, in Rat Urine Associated with Urinary bladder Carcinogenesis

Monocyclic aromatic amines, o-toluidine (o-Tol) and its structural analog o-anisidine (o-Ans), are IARC Group 1 and Group 2A urinary bladder carcinogens, respectively, and are involved in metabolic activation and DNA damage. Our recent study revealed that 2-methyl-N⁴-(2-methylphenyl) benzene-1,4-diamine (MMBD), a p-semidine-type homodimer of o-Tol, was detected and identified in an in vitro reaction of o-Tol with S9 mix and in vivo urinary samples of o-Tol-exposed rats. Potent mutagenic, genotoxic, and cytotoxic activities were reported with MMBD, suggesting its involvement in urinary bladder carcinogenesis. However, it remains unknown whether o-Ans is converted to active metabolites to induce DNA damage in a similar manner as o-Tol. In this study, we report that a novel o-Ans metabolite, 2-methoxy-N⁴-(2-methoxyphenyl) benzene-1,4-diamine (MxMxBD), a dimer by head-to-tail binding (p-semidine form), was for the first time identified in o-Ans-exposed rat urine. MxMxBD induced a stronger mutagenicity in N-acetyltransferase overexpressed Salmonella typhimurium strains and potent genotoxicity and cytotoxicity in human bladder carcinoma T24 cells compared with o-Ans. These results suggest that MxMxBD may to some extent contribute toward urinary bladder carcinogenesis. In addition to homodimerization, such as MxMxBD, heterodimerizations were observed when o-Ans was coincubated with o-Tol or aniline (Ani) in in vitro reactions with S9 mix. This study highlights the important consideration of homodimerizations and heterodimerizations of monocyclic aromatic amines, including o-Ans, o-Tol, and Ani, in the evaluation of the combined exposure risk of bladder carcinogenesis.

Specialized Flavoprotein Promotes Sulfur Migration and Spiroaminal Formation in Aspirochlorine Biosynthesis

Epidithiodiketopiperazines (ETPs) are a class of ecologically and medicinally important cyclodipeptides bearing a reactive transannular disulfide bridge. Aspirochlorine, an antifungal and toxic ETP isolated from Aspergillus oryzae used in sake brewing, deviates from the common ETP scaffold owing to its unusual ring-enlarged disulfide bridge linked to a spiroaminal ring system. Although this disulfide ring system is implicated in the biological activity of ETPs the biochemical basis for this derailment has remained a mystery. Here we report the discovery of a novel oxidoreductase (AclR) that represents the first-in-class enzyme catalyzing both a carbon-sulfur bond migration and spiro-ring formation, and that the acl pathway involves a cryptic acetylation as a prerequisite for the rearrangement. Genetic screening in A. oryzae identified aclR as the candidate for the complex biotransformation, and the aclR-deficient mutant provided the biosynthetic intermediate, unexpectedly harboring an acetyl group. In vitro assays showed that AclR alone promotes 1,2-sulfamyl migration, elimination of the acetoxy group, and spiroaminal formation. AclR features a thioredoxin oxidoreductase fold with a noncanonical CXXH motif that is distinct from the CXXC in the disulfide forming oxidase for the ETP biosynthesis. Crystallographic and mutational analyses of AclR revealed that the CXXH motif is crucial for catalysis, whereas the flavin-adenine dinucleotide is required as a support of the protein fold, and not as a redox cofactor. AclR proved to be a suitable bioinformatics handle to discover a number of related fungal gene clusters that potentially code for the biosynthesis of derailed ETP compounds. Our results highlight a specialized role of the thioredoxin oxidoreductase family enzyme in the ETP pathway and expand the chemical diversity of small molecules bearing an aberrant disulfide pharmacophore.

Association between dietary intake and the prevalence of tumourigenic bacteria in the gut microbiota of middle-aged Japanese adults

The relative contribution of diet to colorectal cancer (CRC) incidence is higher than that for other cancers. Animal models have revealed that Escherichia coli containing polyketide synthase (pks⁺ E. coli) in the gut participates in CRC development. The purpose of this cross-sectional study was to examine the relationship between dietary intake and the prevalence of pks⁺ E. coli isolated from the microbiota in faecal samples of 223 healthy Japanese individuals. Dietary intake was assessed using a previously validated brief-type self-administered diet history questionnaire. The prevalence of pks⁺ E. coli was evaluated using faecal samples collected from participants and specific primers that detected pks⁺ E. coli. The prevalence of pks⁺ E. coli was 26.9%. After adjusting for baseline confounders, the prevalence of pks⁺ E. coli was negatively associated with the intake of green tea (odds ratio [OR], 0.59 [95% confidence interval (CI) 0.30-0.88] per 100 g/1,000 kcal increment) and manganese (OR, 0.43 [95% CI 0.22-0.85] per 1 mg/1,000 kcal increment) and was positively associated with male sex (OR, 2.27 [95% CI 1.05-4.91]). While futher studies are needed to validate these findings, these results provide insight into potential dietary interventions for the prevention of CRC.

Characterization of Colibactin-Producing Escherichia coli Isolated from Japanese Patients with Colorectal Cancer

We investigated the relationship between colibactin-producing (clb⁺) Escherichia coli and colorectal adenocarcinoma. In total, 729 E. coli colonies were isolated from tumor and surrounding non-tumor regions in resected specimens from 34 Japanese patients; 450 colonies were from the tumor regions and 279 from the non-tumor regions. clb⁺ bacteria were found in tumor regions of 11 patients (11/34, 32.4%) and they were also detected in the non-tumor regions of 7 out of these 11 patients (7/34, 20.6%). The prevalence of clb⁺ isolates was 72.7% (327/450) and 44.1% (123/279) in tumor and non-tumor regions, respectively. All the recovered clb⁺ isolates belonged to the phylogenetic group B2 and were the most predominant type in tumor regions. Hemolytic (α-hemolysin-positive, hlyA⁺) and non-hemolytic (α-hemolysin-negative, hlyA^-) clb⁺ isolates were obtained from patient #19; however, the prevalence of hlyA⁺ clb⁺ isolates was significantly higher in tumor regions (35/43, 81.4%) than in non-tumor regions (3/19, 15.8%). Moreover, a significantly higher production of N-myristoyl-D-asparagine, a by-product of colibactin biosynthesis, was observed in hlyA⁺ clb⁺ isolates than in hlyA^- clb⁺ isolates. Our results suggest that hlyA⁺ clb⁺ E. coli may have a selective advantage in colorectal colonization and, consequently, might play a role in carcinogenesis. The presence of hlyA⁺ clb⁺ bacteria in healthy individuals is a potential risk marker of colorectal cancer.

In vitro genotoxicity analyses of colibactin-producing E. coli isolated from a Japanese colorectal cancer patient

Colibactin is a polyketide-peptide genotoxin produced by enteric bacteria such as E. coli, and is considered to contribute to the development of colorectal cancer. We previously isolated E. coli strains from Japanese colorectal cancer patients, and in the present study we investigated the genotoxic potency of the colibactin-producing (clb⁺) E. coli strains that carry the polyketide synthases "pks" gene cluster (pks⁺) and an isogenic clb^- mutant in which the colibactin-producing ability is impaired. Measurement of phosphorylated histone H2AX indicated that DNA double strand breaks were induced in mammalian CHO AA8 cells infected with the clb⁺ E. coli strains. Induction of DNA damage response (SOS response) by crude extract of the clb⁺ strains was 1.7 times higher than that of the clb^- E. coli in an umu assay with a Salmonella typhimurium TA1535/pSK1002 tester strain. Micronucleus test with CHO AA8 cells revealed that infection with the clb⁺ strains induced genotoxicity, i.e., the frequencies of micronucleated cells infected with clb⁺ strain were 4-6 times higher than with the clb^- strain. Since the intestinal flora are affected by dietary habits that are strongly associated with ethnicity, these data may contribute to both risk evaluation and prevention of colorectal cancer in the Japanese population.

Genotyping of a gene cluster for production of colibactin and in vitro genotoxicity analysis of Escherichia coli strains obtained from the Japan Collection of Microorganisms

Introduction

Colibactin is a small genotoxic molecule produced by enteric bacteria, including certain Escherichia coli (E. coli) strains harbored in the human large intestine. This polyketide-peptide genotoxin is considered to contribute to the development of colorectal cancer. The colibactin-producing (clb ⁺) microorganisms possess a 54-kilobase genomic island (clb gene cluster). In the present study, to assess the distribution of the clb gene cluster, genotyping analysis was carried out among E. coli strains randomly chosen from the Japan Collection of Microorganisms, RIKEN BRC, Japan.

Findings

The analysis revealed that two of six strains possessed a clb gene cluster. These clb ⁺ strains JCM5263 and JCM5491 induced genotoxicity in in vitro micronucleus (MN) tests using rodent CHO AA8 cells. Since the induction level of MN by JCM5263 was high, a bacterial umu test was carried out with a cell extract of the strain, revealing that the extract had SOS-inducing potency in the umu tester bacterium.

Conclusion

These results support the observations that the clb gene cluster is widely distributed in nature and clb ⁺ E. coli having genotoxic potencies is not rare among microorganisms.

Genomic Mushroom Hunting Decrypts Coprinoferrin, A Siderophore Secondary Metabolite Vital to Fungal Cell Development

LaeA is a positive global regulator of secondary metabolism in Ascomycetes, but its role in Basidiomycetes, including medicinal mushrooms, remains uncharacterized. Here, knockout of laeA in the model mushroom Coprinopsis cinerea unexpectedly upregulated the biosynthesis of a novel siderophore, coprinoferrin. Furthermore, knockout of the nonribosomal peptide synthetase-encoding cpf1 responsible for coprinoferrin biosynthesis resulted in growth defect and loss of fruiting body formation, indicating the complex role that this natural product plays in fungal cell development.

Activity-Based Probe for Screening of High-Colibactin Producers from Clinical Samples

While high-colibactin-producing Escherichia coli is thought to be associated with colorectal oncogenesis, this study is complicated part due to an inability to isolate colibactin adequately. Here, we created fluorescent probes activated by ClbP, the colibactin-maturing peptidase, to identify high-colibactin-producing strains. Our probe served as a valuable clinical diagnostic tool that allowed simple high-throughput diagnostic screening of clinical samples. Furthermore, the probe also allowed identification of high-colibactin producers that would help advance our understanding of colibactin biosynthesis.

Biosynthesis of lagopodins in mushroom involves a complex network of oxidation reactions

Targeted gene knockout in Coprinopsis cinerea, yeast in vivo bioconversion and in vitro assays elucidated the lagopodin biosynthetic pathway, including a complexity-generating network of oxidation steps.