Journal of Microbiology

Journal Article

The C-22 sterol desaturase Erg5 is responsible for ergosterol biosynthesis and conidiation in Aspergillus fumigatus: Nanbiao Long , Guowei Zhong; J. Microbiol. 2022;60(6):620-626. Published online April 18, 2022; DOI: https://doi.org/10.1007/s12275-022-1564-7

Abstract: Aspergillus fumigatus is the most prevalent saprophytic fungi and can cause severe invasive aspergillosis in immunocompromised individuals. For infection of A. fumigatus, the small hydrophobic conidia have been shown to play a dominant role. In this study, we found that deletion of erg5, a C-22 sterol desaturase gene which function in the last two steps of ergosterol biosynthesis, was sufficient to block ergosterol biosynthesis and conidiation. The deletion phenotype was further verified by a conditional expression strain of erg5 using the inducible tet-on system. Strikingly, erg5 mutant displays increased susceptibility to antifungal azoles itraconazole. RNA sequencing analysis showed that erg5 deficiency resulted in changes in transcription mainly related to lipid, carbohydrate, and amino acid metabolism. Genes encoding ergosterol biosynthesis- related enzymes were found to be up-regulated in erg5 null mutants. However, genes involved in asexual development, including upstream regulators, melanin biosynthesis enzymes, heterotrimeric G proteins, and MAPK signaling, were down-regulated to various degrees. Furthermore, metabolomic study revealed that erg5 deficiency also resulted in altered lipid and amino acid metabolism, which was consistent with our transcriptomics analysis. Collectively, our study established a link between ergosterol biosynthesis and asexual development at the transcriptomics and metabolomics level in A. fumigatus.

Phylogenetic study of penicillium chrysogenum based on the amino acid sequence analysis of chitin synthase: Park, Bum Chan , Lee, Dong Hun , Bae, Kyung Sook , Park, Hee Moon; J. Microbiol. 1997;35(3):159-164.

Abstract: The phylogenetic study of Penicilium chrysogenum was performed based on amino acid sequence comparison of chitin synthase. Phylogenetic trees were constructed with the deduced amino acid sequences of the highly conserved region of chitin synthase gene fragments amplified by PCR. The BlasP similarity search and the bootstrap analysis of the deduced amino acid sequences of chitin synthase from P. chrysogenum with those form other fungi showed a close evolutionary relationship of Penicillium to ascomycetous fungi, especially to genus Aspergilus. The result from bootstrap analysis of the deduced amino acid sequences of the Class II chitin synthase from ascomyceteous fungi supported the usefulness of the Class II chitin synthease for phylogenetic study of filamentous fungi.

Genomic Organization of Penicillium chrysogenum chs4, a Class III Chitin Synthase Gene: Yoon-Dong Park , Myung-Sook Lee , Ji-Hoon Kim , Jun Namgung , Bum Chan Park , Kyung Sook Bae , Hee-Moon Park; J. Microbiol. 2000;38(4):230-238.

Abstract: Class III chitin synthases in filamentous fungi are important for hyphal growth and differentiation of several filamentous fungi. A genomic clone containing the full gene encoding Chs4, a class III chitin synthase in Penicillium chrysogenum, was cloned by PCR screening and colony hybridization from the genomic library. Nucleotide sequence analysis and transcript mapping of chs4 revealed an open reading frame (ORF) that consisted of 5 exons and 4 introns and encoded a putative protein of 915 amino acids. Nucleotide sequence analysis of the 5?lanking region of the ORF revealed a potential TATA box and several binding sites for transcription activators. The putative transcription initiation site at ?6 position was identified by primer extension and the expression of the chs4 during the vegetative growth was confirmed by Northern blot analysis. Amino acid sequence analysis of the Chs4 revealed at least 5 transmembrane helices and several sites for post-translational modifications. Comparison of the amino acid sequence of Chs4 with those of other fungi showed a close relationship between P. chr ysogenum and genus Aspergillus.

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