Acyl-CoA-binding proteins function in plant stress responses

Abstract

Acyl-CoA-binding proteins (ACBPs) show conservation at the acyl-CoA-binding domain which facilitates binding to acyl-CoA esters. These proteins, found in eukaryotes, are grouped into four classes based on their molecular mass and the presence of domains, such as the ankyrin repeats and Kelch motifs, which enable protein-protein interaction. In each of the model plants, Arabidopsis thaliana (thale cress) and Oryza sativa (rice), six genes have been reported to encode ACBPs. Several of these in both A. thaliana and O. sativa, were observed to be induced by various forms of abiotic stress, including drought, heavy metals and low temperature. In contrast, the Class III ACBPs such as AtACBP3 and OsACBP5 were associated with pathogen defense. Transgenic Arabidopsis AtACBP3-overexpressors were conferred resistance to Pseudomonas syringae while its homologue in rice (OsACBP5) was induced by Magnaporthe grisea. When OsACBP5 was overexpressed in Arabidopsis, the resultant transgenic lines were conferred resistance not only to the bacterial biotroph P. syringae but to fungal pathogens. Changes in protein expression in R. solani-infected Arabidopsis OsACBP5-overexpressors (OsACBP5-OEs) were investigated using proteomic analysis. The results obtained suggest that the upregulation of stress-related proteins in OsACBP5-OEs provided protection against various plant pathogens.