The acyl-CoA-binding protein VdAcb1 is essential for carbon starvation response and contributes to virulence in .

UNLABELLED

In the face of carbon, nitrogen, and phosphorus starvation, microorganisms have evolved adaptive mechanisms to maintain growth. In a previous study, we identified a protein predicted to contain acyl-CoA-binding domains in the plant pathogenic fungus . The predicted protein, designated VdAcb1, possesses an atypical signal peptide. However, the functions of this acyl-CoA-binding protein in are not clear. In this research, in vivo or in vitro assays confirmed that VdAcb1 is secreted extracellularly from , although it does not have the typical signal peptide. Furthermore, the unconventional secretion of VdAcb1 was dependent on VdGRASP, a member of the compartment for unconventional protein secretion (CUPS). The deletion mutant strain of (Δ exhibited significant sensitivity to carbon starvation. RNA-seq revealed that the expression of genes related to filamentous growth (MSB2 pathway) and sugar transport were regulated by under conditions of carbon starvation. Yeast one-hybrid experiments further showed that the expression of VdAcb1 was positively regulated by the transcription factor VdMsn4. The Δ strain showed significantly reduced virulence on and . We hypothesize that under conditions of carbon starvation, the expression of is activated by VdMsn4 and VdAcb1 is secreted into the extracellular space. In turn, this activates the downstream MAPK pathway to enhance filamentous growth and virulence of .

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s42994-024-00175-3.