Project description:The direct photosynthetic production of polyhydroxyalkanoate in cyanobacteria was improved by increasing carbon flux to biosynthetic pathway and introducing enzyme with higher activity. To understand the global transcriptional changes under photoautotrophic PHA biosynthesis conditions, RNA-seq analysis was performed. Transcriptomes of recombinant Synechocystis sp. with different PHA-producing potential (three strains, two biological replicates for each strain) were analyzed.
Project description:Iron sulfur clusters (ISC) are essential cofactors that participate in electron transfer, environment sensing, and catalysis. Amongst the most ancient ISC containing proteins are the ferredoxin family of electron carriers. Humans have two ferredoxins, FDX1 and FDX2, localized to the mitochondria and important for ISC synthesis itself. We previously showed that hypoxia can bypass the requirement for some, but not all, components of the ISC biosynthetic pathway, but ferredoxins were not tested at that time. Here we report that FDX1 and its reductase FDXR, but not FDX2, are dispensable under ambient 1% O2 in cultured cells. We find that FDX1 is essential for production of the lipoic acid cofactor, which is synthesized by the ISC containing enzyme lipoyl synthase (LIAS). While hypoxia can rescue the growth phenotype of either FDX1 or LIAS knockout cells, lipoylation is not rescued, arguing against an alternative biosynthetic route or salvage pathway for lipoate in hypoxia. Our work identifies a role for FDX1/LIAS in lipoate synthesis and surprisingly reveals dispensability of lipoic acid altogether under low oxygen tensions in cell culture.
2023-07-28 | PXD042589 | Pride
Project description:Analysis of the biosynthetic pathway of 2-Phenylethanol production in Annulohypoxylon stygium
Project description:Plants make complex and potent therapeutic molecules, but difficulties in sourcing from natural producers or chemical synthesis can challenge their use in the clinic. A prominent example is the anti-cancer therapeutic paclitaxel (Taxol®) from yew (Taxus) trees. Identification of the full paclitaxel biosynthetic pathway would enable heterologous drug production, but it has eluded discovery despite a half century of intensive research. Within the search space of Taxus' large, enzyme-rich genome, we suspected the complex paclitaxel pathway would be difficult to resolve using conventional gene co-expression analysis and small sample sets. To improve the resolution of gene set identification, we developed a multiplexed perturbation strategy to transcriptionally profile cell states spanning tissues, cell types, developmental stages, and elicitation conditions. This approach revealed a set of paclitaxel biosynthetic genes that segregate into expression modules that suggest consecutive biosynthetic sub-pathways. These modules resolved seven new genes that, when combined with previously known enzymes, are sufficient for the de novo biosynthesis and isolation of baccatin III, an industrial precursor for Taxol, in Nicotiana benthamiana leaves at levels comparable to the natural abundance in Taxus needles. Included are taxane 1β-hydroxylase (T1βH), taxane 9α-hydroxylase (T9αH), taxane 7β-O-acyltransferase (T7ΑΤ), taxane 7β-O-deacetylase (T7dA), taxane 9α-O-deacetylase (T9dA), and taxane 9-oxidase (T9ox). Importantly, the T9αH we discovered is distinct and independently evolved from those recently reported, which failed to yield baccatin III with downstream enzymes. Unexpectedly, we also found a nuclear transport factor 2 (NTF2)-like protein (FoTO1) crucial for high yields of taxanes; this protein promotes the formation of the desired product during the first taxane oxidation step, resolving a longstanding bottleneck in paclitaxel pathway reconstitution. Together with a new β-phenylalanine-CoA-ligase, the eight genes discovered in this study enables the complete reconstitution of 3’-N-debenzoyl-2’-deoxy-paclitaxel with a 20-enzyme pathway in Nicotiana plants. More broadly, we establish a generalizable approach for pathway discovery that scales the power of co-expression studies to match the complexity of specialized metabolism, enabling discovery of gene sets responsible for high-value biological functions.
Project description:Microarray analysis performed with an evolved strain derived from the industrial strain EthanolRed for accession of the differential expression level of the strain with the biosynthetic pathway for production of isobutanol versus the wild-type strain.
Project description:A bifunctional peroxidase enzyme, 4-coumarate 3-hydroxylase (C3H/APX), provides a parallel route to the shikimate shunt pathway for the conversion of 4-coumarate to caffeate in the early steps of lignin biosynthesis. Knockdown of C3H/APX (c3h/apx) expression has been shown to reduce the lignin content in Brachypodium distachyon. However, like many other lignin-modified plants, c3h/apx plant shows unpredictable pleiotropic phenotypes, including stunted growth, delayed senescence, and reduced seed yield. A system-wide level understanding of altered biological processes in lignin-modified plants can help pinpoint the lignin-modification associated growth defects to benefit future studies aiming to negate the yield penalty. Here, a global proteomics measurement of the stem tissue of the model grass Brachypodium distachyon was used to investigate the underlying mechanism of c3h/apx-associated lignin modification and negative growth phenotype. Our findings demonstrate that C3H/APX knockdown in Brachypodium stems substantially alters the abundance of enzymes implicated in the phenylpropanoid biosynthetic pathway and disrupt cellular redox homeostasis. Moreover, it elicits plant defense response associated with intracellular kinases and phytohormone-based signaling to facilitate growth-defense trade-offs. A deeper understanding along with potential targets to mitigate the pleiotropic phenotypes identified in this study could aid to increase the economic feasibility of lignocellulosic biofuel production.
Project description:On the example of the biosynthetically exhausted landomycin A cluster we demonstrate unbalancing of gene transcription as an efficient method for the generation of new compounds. Decoupled from the native regulators LanI and LanK, all landomycin A structural genes were set under the control of a single synthetic promoter and expressed in a heterologous host Streptomyces albus J1074. Previously being both temporarily and quantitatively regulated, these genes were transcribed as a single polycistronic mRNA leading to the production of four novel and two known compounds. No glycosylated landomycins were detected though the entire biosynthetic cluster was transcribed, showing the crucial role of the balanced gene expression for the production of landomycin A. Two new compounds, fridamycin F and G, isolated in this study were shown to originate from the interplay between the expressed biosynthetic pathway and metabolic network of the heterologous host. Structure activity studies of the isolated compounds as well as results of transcriptome sequencing are discussed in this article. Comparison of gene expression of the H2-26 cosmid (encoding landomycin A biosynthetic genes) with H2-26-act, where an additional constitutive promoter cassette was integrated to drive biosynthetic genes transcription.
Project description:The direct photosynthetic production of polyhydroxyalkanoate in cyanobacteria was improved by increasing carbon flux to biosynthetic pathway and introducing enzyme with higher activity. To understand the global transcriptional changes under photoautotrophic PHA biosynthesis conditions, RNA-seq analysis was performed.