Akiyama, D. Y. | bioRxiv Science

bioRxiv2021

Chromatin profiling reveals genome stability heterogeneity in clinical isolates of the human pathogen Aspergillus fumigatus

Invasive Pulmonary aspergillosis is a life-threatening infection in immunosuppressed patients caused by the filamentous fungus Aspergillus fumigatus. Chromatin structure regulation is important for genome stability maintenance and has the potential to lead to genome rearrangements driving differences in virulence and pathogenesis of different A. fumigatus isolates. Here, we compared the chromatin activities of the most investigated clinical isolates Af293 and CEA17 and uncovered striking differences in the number, locations and expression of transposable elements. We found evidence for higher genome instability in Af293 as compared to CEA17 and identified a spontaneous Af293 variant that exhibits gross chromosomal alterations including the loss of a 320 kb long segment in chromosome VIII and the amplification of a biosynthetic gene cluster. As a consequence of these re-arrangements, the variant shows increased secondary metabolites production, growth and virulence. Our work emphasizes genome stability heterogeneity as an evolutionary driver of A. fumigatus fitness and virulence.

molecular biology↗

bioRxiv2020

The histone deacetylase clr3regulates secondary metabolite production and growth under oxidative stress conditions in Penicillium brasilianum

Most of the biosynthetic gene clusters (BGCs) found in filamentous fungi are silent under standard laboratory cultivation conditions due to the lack of expression triggering stimuli, representing a considerable drawback in drug discovery. To access the full biosynthetic potential of these microbes, studies towards the activation of cryptic BGCs are essential. Histone acetylation status is an important regulator of chromatin structure which impacts in cell physiology and, therefore, expression of biosynthetic gene clusters in filamentous fungi. Histone deacetylases (HDACs) and histone acetyl-transferases (HATs) are responsible for maintaining and controlling this process under different cell conditions. In this study, clr3, a gene encoding a histone deacetylase in Penicillium brasilianum was deleted and associated phenotypic and metabolic changes evaluated. Results indicate reduced growth under oxidative stress conditions in the {Delta}clr3 knockout strain. Also, the production of several secondary metabolites including austin-related meroterpenoids, brasiliamides, mycotoxins such as verruculogen and penicillic acid, as well as cyclodepsipeptides was reduced in the {Delta}clr3 strain when compared to wild-type strain. Accordingly, addition of epigenetic modulators responsible for HDAC inhibition such as suberoylanilide hydroxamic acid (SAHA) and nicotinamide (NAA) to P. brasilianum growth media also culminated in reduction of secondary metabolite production. Mass Spectrometry Imaging (MSI) was applied to compare metabolite production and spatial distribution on the colony. Results suggest that Clr3 plays an important role in secondary metabolite biosynthesis in P. brasilianum, thus offering new strategies for regulation of natural product synthesis by assessing chromatin modification in P. brasilianum.

microbiology↗