Figure 7 Phylogenetic tree showing the evolutive distances amongst IATs and putatives IALs from
several ascomycetes. The IAT of P. chrysogenum (GenBank: P15802), the IAT of A. nidulans (GenBank: P21133) and a hypothetical protein of A. oryzae which shares 84% identity with the P. chrysogenum IAT (GenBank: XP_001825449), were compared to the P. chrysogenum IAL and putative homologues of this protein that are present in different PLX4032 clinical trial ascomycetes, such as A. oryzae (GenBank: BAE55742), A. clavatus (GenBank: XP_001271254), A. niger (GenBank: XP_001399990), A. terreus (GenBank: https://www.selleckchem.com/products/dibutyryl-camp-bucladesine.html XP_001213312 and XP_001216532), N. fischeri (GenBank: XP_001263202), A. fumigatus (GenBank: XP_754359) and A. nidulans (aatB-encoded protein GenBank: XP_664379). Sequences were aligned using the MegAlign program (Lasergene, DNASTAR, Inc.). Intron content of the genes encoding these proteins is indicated in brackets. Genes encoding IATs in P. chrysogenum, A. nidulans and A. oryzae contain three introns, thus differing from those genes encoding IAL and IAL-homologues (Fig. 7). Only the aatB gene encoding the A. nidulans IAL homologue and one of the A. terreus ial gene homologue (GenBank: XP_001213312), contain three introns. This suggests that
alternatively, ial and ial gene homologues might have had a different origin from the IAT-encoding genes (penDE or aatA genes), selleck products thus encoding proteins with a different function as it was confirmed by the lack of penicillin biosynthetic activity of the P. chrysogenum IAL. With this hypothesis, only the aatB gene from A. nidulans would be a real paralogue of the IAT-encoding gene (aatA) formed by gene duplication from a common ancestor. This is supported by the Alanine-glyoxylate transaminase presence of penicillin forming activity of the aatB-encoded IAL homologue and by the presence of the same transcription factors binding to the promoter
regions of these two genes . Conclusion If there was a common ancestor for the ial and penDE genes, most of the Ascomycota fungi initially had the potential capacity to perform the acyltransferase reaction. However, only a few of them, like A. nidulans and P. chrysogenum, were able to develop during evolution, the penDE encoding the highly functional IAT enzyme. The penDE gene was linked to the first two genes (of bacterial origin) of the penicillin pathway, which endowed these microorganisms with an important ecological advantage because of the ability to generate aromatic penicillins. It is likely that the de novo formation of this cluster occurred in a common ancestor of the genera Penicillium and Aspergillus, since the pen cluster is present in several species of those genera [40–42]. However, not all genomes of the aspergilli contain the pen cluster; e.g., A. fumigatus lacks it, although it contains the ial gene.