Gluten-Degrading Proteases in Wheat Infected by Fusarium graminearum—Protease Identification and Effects on Gluten and Dough Properties

Abstract

Recently, we have observed a relationship between poor breadmaking quality and protease activities related to fungal infection. This study aims to identify potential gluten-degrading proteases secreted by fungi and to analyze effects of these proteases on rheological properties of dough and gluten. Fusarium graminearum-infected grain was used as a model system. Zymography showed that serine-type proteases secreted by F. graminearum degrade gluten proteins. Zymography followed by liquid chromatography–mass spectrometry (MS)/MS analysis predicted one serine carboxypeptidase and seven serine endo-peptidases to be candidate fungal proteases involved in gluten degradation. Effects of fungal proteases on the time-dependent rheological properties of dough and gluten were analyzed by small amplitude oscillatory shear rheology and large deformation extensional rheology. Our results indicate that fungal proteases degrade gluten proteins not only in the grain itself, but also during dough preparation and resting. Our study gives new insights into fungal proteases and their potential role in weakening of gluten.

Wheat Fusarium Protease Specificity and Effect on Dough Properties

“…In all cases, the relative R max loss was greater at 135 min than at 45 min ( Figure 1 b), demonstrating that longer rest times resulted in a greater reduction in R max . This is consistent with previous reports, showing that in addition to damage during seed maturation, Fusarium protease damage occurs during fermentation [ 4 , 16 ]. The comparison of 45 and 135 min extensigraph data was effective at revealing the offsetting gluten strength loss due to protease from the expected gain from continued dough development (re-polymerization).…”

“…Fusarium infection reduces wheat end-use quality [ 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 ], presumably by impairing seed maturation and digestion of starch and protein for sustenance. Fusarium proteases remain dormant in harvested seed but reactivate during dough making, thus affecting dough handling properties and baking performance [ 14 , 15 , 16 , 17 ]. While a large amount of work has been carried out in this field, most research has been based on non-specific tests [ 3 , 15 , 18 ] or proteomic/genomic identification of gene sequences [ 19 ].…”

Hydrolytic enzymes and their directly and indirectly effects on gluten and dough properties: An extensive review

“…The impact of peptidase hydrolysis on rheological properties is reported in different researches (Ahmed & Ikram, 2015;Koga et al, 2019). Peptidase hydrolysis reduced storage modulus (G´) (Ahmed & Ikram, 2015) and gluten consistency (Koga et al, 2019) due to gluten degradation and digesting effect of protease. In the gluten samples treated with protease, the glutenin polymer size is notably decreased which leads to reduction in maximum resistance to extension (R max ).…”

“…Aspergillopepsin (EC 3.4.23.18) from A. niger further showed glutendegrading activity; compared with AN-PEP, however, it was not nearly as substrate-specific and efficient, hence the fact that it might only be utilized complementary to Endoprotease B, isoform 2 (EP-B2), or AN-PEP, for instance (Ehren et al, 2009). F. graminearum proteases are not only able to degrade gluten proteins in the grain itself, but also capable of weakening gluten during dough preparation and resting (Koga et al, 2019). These proteases were observed to be essentially trypsin-like serine proteases cutting the proteins at the lysine or arginine amino acid (Pekkarinen et al, 2007).…”

Characterization of Bacillus cereus AFA01 Capable of Degrading Gluten and Celiac-Immunotoxic Peptides

“…Recently, some gluten-degrading bacteria and gluten-degrading enzymes have been discovered and studied on the detoxification of gluten, such as Fusarium graminearum [10], Microdochium majus [11], Bacillus spp. [12], actinidin from kiwifruit [13], and a serine protease from Burkholderia gladioli [14].…”