Polyamines Upregulate Cephalosporin C Production and Expression of β-Lactam Biosynthetic Genes in High-Yielding Acremonium chrysogenum Strain.

Alexander A Zhgun,Mikhail A Eldarov

doi:10.3390/molecules26216636

Abstract

The high-yielding production of pharmaceutically significant secondary metabolites in filamentous fungi is obtained by random mutagenesis; such changes may be associated with shifts in the metabolism of polyamines. We have previously shown that, in the Acremonium chrysogenum cephalosporin C high-yielding strain (HY), the content of endogenous polyamines increased by four- to five-fold. Other studies have shown that the addition of exogenous polyamines can increase the production of target secondary metabolites in highly active fungal producers, in particular, increase the biosynthesis of β-lactams in the Penicillium chrysogenum Wis 54–1255 strain, an improved producer of penicillin G. In the current study, we demonstrate that the introduction of exogenous polyamines, such as spermidine or 1,3-diaminopropane, to A. chrysogenum wild-type (WT) and HY strains, leads to an increase in colony germination and morphological changes in a complete agar medium. The addition of 5 mM polyamines during fermentation increases the production of cephalosporin C in the A. chrysogenum HY strain by 15–20% and upregulates genes belonging to the beta-lactam biosynthetic cluster. The data obtained indicate the intersection of the metabolisms of polyamines and beta-lactams in A. chrysogenum and are important for the construction of improved producers of secondary metabolites in filamentous fungi.

Highlights

Filamentous fungi are taxonomically diverse organisms from phylum Ascomycota and Zygomycota with filamentous hyphae and the ability to produce airborne spores or conidia
We studied the expression of biosynthetic genes of the “early” beta-lactams biosynthetic gene clusters (BGCs): (i) gene pcbAB for ACV (δ-[L-α-Aminoadipyl]-L-Cysteinyl-D-Valine) synthetase (EC: 6.3.2.26), the central enzyme in the biosynthesis of beta-lactams, which creates in ACV tripeptide as NRPS; (ii) gene pcbC for isopenicillin N-synthase (EC: 1.21.3.1), oxygenase, which synthesizes penicillin N (IPN) from the ACV tripeptide; (iii) gene cefD1 for isopenicillin N-CoA synthetase (EC: 5.1.1.17), IPN epimerase component 1, which activates IPN by the acyl-CoA synthase; (iv) gene cefD2 for isopenicillin N-CoA epimerase (EC: 5.1.1.17), IPN epimerase component 2, which epimerizes IPN-CoA to penicillin N (PenN)
We studied the expression of biosynthetic genes of the “late” betalactams BGC: (v) gene cefEF for deacetoxycephalosporin C synthetase (EC 1.14.20.1)/deacetoxycephalosporin C hydroxylase (1.14.11.26), which sequentially catalyzes two oxygenase reactions for the conversion of PenN to DAOC and to deacetylcephalosporin C (DAC); (vi) gene cefG for deacetylcephalosporin-C acetyltransferase (EC 2.3.1.175), which transfers the acetyl residue from acetyl coenzyme A to the DAC to produce CPC

Summary

Introduction

Filamentous fungi ( called molds or moldy fungi) are taxonomically diverse organisms from phylum Ascomycota and Zygomycota with filamentous hyphae and the ability to produce airborne spores or conidia. Improved strains of filamentous fungi are one of the most important sources for producing pharmaceutically significant secondary metabolites (SMs), such as antibiotics, statins, and immunosuppressants [1,2,3,4]. These compounds are one of the most commonly prescribed drugs worldwide [5,6]. The HY strain is one of the most comprehensively characterized among the improved A. chrysogenum producers of CPC [2,11] For this strain, the chromosomal rearrangements compared to WT strain were shown; the number of copies and localization of biosynthetic gene clusters (BGCs) of betalactams, the so-called “early” and “late” clusters, were determined [12].

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