GuaB3, an overlooked enzyme in cyanobacteria's toolbox that sheds light on IMP dehydrogenase evolution.

IMP dehydrogenase and GMP reductase are enzymes from the same protein family with analogous structures and catalytic mechanisms that have gained attention because of their essential roles in nucleotide metabolism and as potential drug targets. This study focusses on GuaB3, a less-explored enzyme within this family. Phylogenetic analysis uncovers GuaB3's independent evolution from other members of the family and it predominantly occurs in Cyanobacteria.

Metabolic engineering of Ashbya gossypii for limonene production from xylose.

Background: Limonene is a cyclic monoterpene that has applications in the food, cosmetic, and pharmaceutical industries. The industrial production of limonene and its derivatives through plant extraction presents important drawbacks such as seasonal and climate issues, feedstock limitations, low efficiency and environmental concerns. Consequently, the implementation of efficient and eco-friendly bioprocesses for the production of limonene and other terpenes constitutes an attractive goal for microbial biotechnology.

Genomic Edition of Using One-vector CRISPR/Cas9.

The CRISPR/Cas9 system is a novel genetic tool which allows the precise manipulation of virtually any genomic sequence. In this protocol, we use a specific CRISPR/Cas9 system for the manipulation of . The filamentous fungus is currently used for the industrial production of riboflavin (vitamina B2).

Sugar transport for enhanced xylose utilization in Ashbya gossypii.

The co-utilization of mixed (pentose/hexose) sugars constitutes a challenge for microbial fermentations. The fungus Ashbya gossypii, which is currently exploited for the industrial production of riboflavin, has been presented as an efficient biocatalyst for the production of biolipids using xylose-rich substrates. However, the utilization of xylose in A.

Multiplex genome editing in Ashbya gossypii using CRISPR-Cpf1.

CRISPR/Cas technologies constitute essential tools for rapid genome engineering of many organisms, including fungi. The CRISPR/Cas9 system adapted for the industrial fungus Ashbya gossypii enables efficient genome editing for the introduction of deletions, insertions and nucleotide substitutions. However, the Cas9 system is constrained by the existence of a specific 5'-NGG-3' PAM sequence in the target site.

Microbial lipids from industrial wastes using xylose-utilizing Ashbya gossypii strains.

This work presents the exploitation of waste industrial by-products as raw materials for the production of microbial lipids in engineered strains of the filamentous fungus Ashbya gossypii. A lipogenic xylose-utilizing strain was used to apply a metabolic engineering approach aiming at relieving regulatory mechanisms to further increase the biosynthesis of lipids. Three genomic manipulations were applied: the overexpression of a feedback resistant form of the acetyl-CoA carboxylase enzyme; the expression of a truncated form of Mga2, a regulator of the main Δ9 desaturase gene; and the overexpression of an additional copy of DGA1 that codes for diacylglycerol acyltransferase.

The Bateman domain of IMP dehydrogenase is a binding target for dinucleoside polyphosphates.

IMP dehydrogenase (IMPDH) is an essential enzyme that catalyzes the rate-limiting step in the guanine nucleotide biosynthetic pathway. Because of its involvement in the control of cell division and proliferation, IMPDH represents a therapeutic for managing several diseases, including microbial infections and cancer. IMPDH must be tightly regulated, but the molecular mechanisms responsible for its physiological regulation remain unknown.

Metabolic engineering of Ashbya gossypii for deciphering the de novo biosynthesis of γ-lactones.

Background: Lactones are highly valuable cyclic esters of hydroxy fatty acids that find application as pure fragrances or as building blocks of speciality chemicals. While chemical synthesis often leads to undesired racemic mixtures, microbial production allows obtaining optically pure lactones. The production of a specific lactone by biotransformation depends on the supply of the corresponding hydroxy fatty acid, which has economic and industrial value similar to γ-lactones.

A Nucleotide-Dependent Conformational Switch Controls the Polymerization of Human IMP Dehydrogenases to Modulate their Catalytic Activity.

Inosine 5'-monophosphate dehydrogenase (IMPDH) catalyzes the rate-limiting step in the de novo GTP biosynthetic pathway and plays essential roles in cell proliferation. As a clinical target, IMPDH has been studied for decades, but it has only been within the last years that we are starting to understand the complexity of the mechanisms of its physiological regulation. Here, we report structural and functional insights into how adenine and guanine nucleotides control a conformational switch that modulates the assembly of the two human IMPDH enzymes into cytoophidia and allosterically regulates their catalytic activity.

Pathway Grafting for Polyunsaturated Fatty Acids Production in Ashbya gossypii through Golden Gate Rapid Assembly.

Here we present a Golden Gate assembly system adapted for the rapid genomic engineering of the industrial fungus Ashbya gossypii. This biocatalyst is an excellent biotechnological chassis for synthetic biology applications and is currently used for the industrial production of riboflavin. Other bioprocesses such as the production of folic acid, nucleosides, amino acids and biolipids have been recently reported in A.

Formation of folates by microorganisms: towards the biotechnological production of this vitamin.

Folates (vitamin B) are essential micronutrients which function as cofactors in one-carbon transfer reactions involved in the synthesis of nucleotides and amino acids. Folate deficiency is associated with important diseases such as cancer, anemia, cardiovascular diseases, or neural tube defects. Epidemiological data show that folate deficiency is still highly prevalent in many populations.

A nucleotide-controlled conformational switch modulates the activity of eukaryotic IMP dehydrogenases.

Inosine-5'-monophosphate dehydrogenase (IMPDH) is an essential enzyme for nucleotide metabolism and cell proliferation. Despite IMPDH is the target of drugs with antiviral, immunosuppressive and antitumor activities, its physiological mechanisms of regulation remain largely unknown. Using the enzyme from the industrial fungus Ashbya gossypii, we demonstrate that the binding of adenine and guanine nucleotides to the canonical nucleotide binding sites of the regulatory Bateman domain induces different enzyme conformations with significantly distinct catalytic activities.

Utilization of xylose by engineered strains of for the production of microbial oils.

Background: is a filamentous fungus that is currently exploited for the industrial production of riboflavin. The utilization of as a microbial biocatalyst is further supported by its ability to grow in low-cost feedstocks, inexpensive downstream processing and the availability of an ease to use molecular toolbox for genetic and genomic modifications. Consequently, has been also introduced as an ideal biotechnological chassis for the production of inosine, folic acid, and microbial oils.

Engineering Ashbya gossypii strains for de novo lipid production using industrial by-products.

Ashbya gossypii is a filamentous fungus that naturally overproduces riboflavin, and it is currently exploited for the industrial production of this vitamin. The utilization of A. gossypii for biotechnological applications presents important advantages such as the utilization of low-cost culture media, inexpensive downstream processing and a wide range of molecular tools for genetic manipulation, thus making A.

Folic Acid Production by Engineered Ashbya gossypii.

Folic acid (vitamin B) is the common name of a number of chemically related compounds (folates), which play a central role as cofactors in one-carbon transfer reactions. Folates are involved in the biosynthesis and metabolism of nucleotides and amino acids, as well as supplying methyl groups to a broad range of substrates, such as hormones, DNA, proteins, and lipids, as part of the methyl cycle. Humans and animals cannot synthesize folic acid and, therefore, need them in the diet.

Bioproduction of riboflavin: a bright yellow history.

Riboflavin (vitamin B) is an essential nutrient for humans and animals that must be obtained from the diet. To ensure an optimal supply, riboflavin is used on a large scale as additive in the food and feed industries. Here, we describe a historical overview of the industrial process of riboflavin production starting from its discovery and the need to produce the vitamin in bulk at prices that would allow for their use in human and animal nutrition.

The filamentous fungus Ashbya gossypii as a competitive industrial inosine producer.

Inosine is a nucleoside with growing biotechnological interest due to its recently attributed beneficial health effects and as a convenient precursor of the umami flavor. At present, most of the industrial inosine production relies on bacterial fermentations. In this work, we have metabolically engineered the filamentous fungus Ashbya gossypii to obtain strains able to excrete high amounts of inosine to the culture medium.

Biotechnology of riboflavin.

Riboflavin (vitamin B2) production has shifted from chemical synthesis to exclusive biotechnological synthesis in less than 15 years. The underlying extraordinary achievement in metabolic engineering and bioprocess engineering is reviewed in this article with regard to the two most important industrial producers Bacillus subtilis and Ashbya gossypii. The respective biosynthetic routes and modifications are discussed, and also the regulation of riboflavin synthesis.

Metabolic engineering of riboflavin production in Ashbya gossypii through pathway optimization.

Background: The industrial production of riboflavin mostly relies on the microbial fermentation of flavinogenic microorganisms and Ashbya gossypii is the main industrial producer of the vitamin. Accordingly, bioengineering strategies aimed at increasing riboflavin production in A. gossypii are highly valuable for industry.

Genomic profiling of fungal cell wall-interfering compounds: identification of a common gene signature.

Background: The fungal cell wall forms a compact network whose integrity is essential for cell morphology and viability. Thus, fungal cells have evolved mechanisms to elicit adequate adaptive responses when cell wall integrity (CWI) is compromised. Functional genomic approaches provide a unique opportunity to globally characterize these adaptive mechanisms.

Increased riboflavin production by manipulation of inosine 5'-monophosphate dehydrogenase in Ashbya gossypii.

Guanine nucleotides are the precursors of essential biomolecules including nucleic acids and vitamins such as riboflavin. The enzyme inosine-5'-monophosphate dehydrogenase (IMPDH) catalyzes the ratelimiting step in the guanine nucleotide de novo biosynthetic pathway and plays a key role in controlling the cellular nucleotide pools. Thus, IMPDH is an important metabolic bottleneck in the guanine nucleotide synthesis, susceptible of manipulation by means of metabolic engineering approaches.

Increased production of inosine and guanosine by means of metabolic engineering of the purine pathway in Ashbya gossypii.

Background: Inosine and guanosine monophosphate nucleotides are convenient sources of the umami flavor, with attributed beneficial health effects that have renewed commercial interest in nucleotide fermentations. Accordingly, several bacterial strains that excrete high levels of inosine and guanosine nucleosides are currently used in the food industry for this purpose.

Results: In the present study, we show that the filamentous fungus Ashbya gossypii, a natural riboflavin overproducer, excretes high amounts of inosine and guanosine nucleosides to the culture medium.

Engineering Ashbya gossypii for efficient biolipid production.

Ashbya gossypii is a filamentous fungus that naturally overproduces riboflavin. Indeed, engineered strains are currently used for the industrial production of riboflavin, replacing the chemical synthesis processes formerly used. The utilization of A.