The role of phenylalanine hydroxylase in lipogenesis in the oleaginous fungus Mortierella alpina

Abstract

Phenylalanine hydroxylase (PAH) catalyses the irreversible hydroxylation of phenylalanine to tyrosine, which is the rate-limiting reaction in phenylalanine metabolism in animals. A variety of polyunsaturated fatty acids can be synthesized by the lipid-producing fungus Mortierella alpina, which has a wide range of industrial applications in the production of arachidonic acid. In this study, RNA interference (RNAi) with the gene PAH was used to explore the role of phenylalanine hydroxylation in lipid biosynthesis in M. alpina. Our results indicated that PAH knockdown decreased the PAH transcript level by approximately 55% and attenuated cellular fatty acid biosynthesis. Furthermore, the level of NADPH, which is a critical reducing agent and the limiting factor in lipogenesis, was decreased in response to PAH RNAi, in addition to the downregulated transcription of other genes involved in NADPH production. Our study indicates that PAH is part of an overall enzymatic and regulatory mechanism supplying NADPH required for lipogenesis in M. alpina.

Metatranscriptomic analysis of tomato rhizospheres reveals insight into plant-microbiome molecular response to biochar-amended organic soil

“…Organic cyclic compounds, such as polyaromatic aromatic hydrocarbons (PAH) and those found in lignin and cellulose, are often found in organic matter (PAH found particularly in contaminated soils) and can be difficult to break down (Tomer et al, 2021;Vipotnik et al, 2021). However, some of the soil fungi identified in this study (e.g., Mortierella, Basidiobolus) have the ability to bind to these compounds, break them down via oxidoreductases (e.g., dioxygenases), and use them as a source of carbon and energy (Cerniglia, 1993;Wang et al, 2020;Wang et al, 2021;Sun et al, 2022), a finding consistent with the enrichment results.…”

Microbial Musings – August 2021

“…We switch to industrial biotechnology for our next paper, which is about understanding factors that lead to lipogenesis in the fungus Mortierella alpina [10]. This is an oleaginous microbe, meaning that under certain growth conditions it can accumulate lipids to very high levels and this species can remarkably reach nearly 50 % of its dry weight as lipids.…”