The Spt10 GNAT Superfamily Protein Modulates Development, Cell Cycle Progression and Virulence in the Fungal Insect Pathogen, Beauveria bassiana.

Qing Cai,Juan-Juan Wang,Dao-Hong Jiang,Jia-Tao Xie,Nemat O Keyhani

doi:10.3390/jof7110905

Abstract

Chromatin remodeling is mediated in part by post-translational acetylation/deacetylation modifications of histones. Histone acetyltransferases (HATs), e.g., members of the GNAT/MYST superfamily, activate gene transcription via promotion of euchromatin formation. Here, we characterized a GNAT family HAT, Spt10 (BbSpt10), in the environmentally and economically important fungal insect pathogen, Beauveria bassiana. Targeted gene knockout of BbSpt10 resulted in impaired asexual development and morphogenesis; reduced abilities to utilize various carbon/nitrogen sources; reduced tolerance to heat, fungicides, and DNA damage stress; and attenuated virulence. The ΔBbSpt10 mutant showed disrupted cell cycle development and abnormal hyphal septation patterns. Transcriptome analyses of wild type and ΔBbSpt10 cells revealed the differential expression of 373 genes, including 153 downregulated and 220 upregulated genes. Bioinformatic analyses revealed downregulated genes to be enriched in pathways involved in amino acid metabolism, cellular transportation, cell type differentiation, and virulence, while upregulated genes were enriched in carbon/nitrogen metabolism, lipid metabolism, DNA process, and cell rescue, defense, and virulence. Downregulated virulence genes included hydrophobins, cellular transporters (ABC and MFS multidrug transporters) and cytochrome P450 detoxification genes. These data indicated broad effects of BbSpt10 on fungal development, multi-stress response, and virulence.

Highlights

IntroductionPublisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations
The open reading frame (ORF) was translated into a protein consisting of 647 amino acids that contained an NAT_SF super family domain in the N-terminal domain
Our data showed that loss of BbSpt10 resulted in smaller blastospores, shortened hyphal cells, which again could be attributed at least in part to the arrested cell cycle phenotype seen in the mutant as compared to the wild type parent. These results indicate that BbSpt10 likely affects hyphal septation and cytokinesis via cell cycle disruption

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Genomic DNA is packaged into a highly ordered chromatin structure. The basic repeating unit of chromatin is the nucleosome, which consists of ~146-bp. DNA wrapped around a histone octamer assembled from two copies of each histone. Changes in chromatin structure govern gene expression, with remodeling processes regulated by at least two general types of chromatin-modifying activities: (i) remodeling complexes, such as SWI/SNF, which move nucleosomes to affect chromatin structure and are dependent on energy generated by ATP hydrolysis [2], and (ii) histone modifying complexes, which modify histones in a post-translational manner, e.g., methylation, acetylation, ubiquitination [3,4]

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