Identification of Two Feruloyl Esterases in Dickeya dadantii 3937 and Induction of the Major Feruloyl Esterase and of Pectate Lyases by Ferulic Acid

Abstract

The plant-pathogenic bacterium Dickeya dadantii (formerly Erwinia chrysanthemi) produces a large array of plant cell wall-degrading enzymes. Using an in situ detection test, we showed that it produces two feruloyl esterases, FaeD and FaeT. These enzymes cleave the ester link between ferulate and the pectic or xylan chains. FaeD and FaeT belong to the carbohydrate esterase family CE10, and they are the first two feruloyl esterases to be identified in this family. Cleavage of synthetic substrates revealed strong activation of FaeD and FaeT by ferulic acid. The gene faeT appeared to be weakly expressed, and its product, FaeT, is a cytoplasmic protein.In contrast, the gene faeD is strongly induced in the presence of ferulic acid, and FaeD is an extracellular protein secreted by the Out system, responsible for pectinase secretion. The product of the adjacent gene faeR is involved in the positive control of faeD in response to ferulic acid. Moreover, ferulic acid acts in synergy with polygalacturonate to induce pectate lyases, the main virulence determinant of soft rot disease. Feruloyl esterases dissociate internal cross-links in the polysaccharide network of the plant cell wall, suppress the polysaccharide esterifications, and liberate ferulic acid, which contributes to the induction of pectate lyases. Together, these effects of feruloyl esterases could facilitate soft rot disease caused by pectinolytic bacteria.

PelN Is a New Pectate Lyase of Dickeya dadantii with Unusual Characteristics

“…GacA is a positive regulator involved in the control of virulence genes during plant infection (40,41). In culture media, the pelN expression was weakly induced in the presence of polygalacturonate (Table 3), but it was not affected by the addition of other molecular inducers of pectate lyase synthesis, such as plant extracts or ferulic acid (1,42). On the other hand, the pelN expression was sensitive to several external physicochemical conditions.…”

The Role of Secretion Systems and Small Molecules in Soft-Rot Enterobacteriaceae Pathogenicity

“…The phenylpropanoid biosynthesis pathway can give rise to a variety of secondary compounds, such as flavonoids, isoflavonoids, stilbenes, and lignin, that are involved in resistance to a broad spectrum of pathogens (49,103). Expression of the Dickeya PCWDE is enhanced by another plant phenolic compound, ferulic acid, and this induction occurs independently of GacA (55). In E. coli, the physiological stimuli of the GacA/S homologs (BarA/UvrY) are formate and acetate (21).…”

Three Feruloyl Esterases in Cellulosilyticum ruminicola H1 Act Synergistically To Hydrolyze Esterified Polysaccharides

“…Bacteria that are reported to possess Fae genes are restricted to a few species, including Butyrivibrio fibrisolvens (9,10), Prevotella ruminicola (15), Clostridium thermocellum (5), and Dickeya dadantii (25). Bioinformatics-based gene screening has indicated that each of these Fae-producing bacteria generally possesses one or two such genes, encoding proteins with distinct enzymatic characteristics.…”

“…Faes are not only relevant in biofuel production but also used in the medical industry for synthesis of bioactive food components (24). Dozens of microorganisms have been reported to secrete Faes, but the Faes described to date are mainly from fungi (4), though several bacterial Faes have been studied (15,20,25,28,31,32). On the basis of their primary sequences and substrate specificity against four model substrates, methyl ferulate (MFA), methyl caffeate (MCA), methyl p-coumarate (MpCA), and methyl sinapate (MSA), Faes are classified as types A, B, C, and D (8,36).…”