In our latest research updates, we explore the fascinating world of fungal and microbial expansin-like proteins and their impact on biomass.
Uncovering Sequence and Structural Characteristics of Fungal Expansins
This study characterized 20 fungal expansin-related proteins, recombinantly expressed in Komagataella phaffii. By examining their binding preferences to cellulosic and chitinous substrates under varied pH conditions, it revealed clear trends: acidic proteins (pI < 5) favored chitin, while basic proteins (pI > 8) showed affinity for xylan. Notably, enhanced cellulose binding correlated with higher aromatic amino acid content and the presence of a CBM63 domain. Principal component analysis reinforced that both overall sequence traits and specific conserved residues were crucial in distinguishing expansin-like “loosenin” activity from classical expansins.
https://doi.org/10.1002/prot.70029
Phylogenetically Distinct Fungal Expansins: Binding Preferences & Enzymatic Enhancement
This open-access article identified two novel fungal expansin-like proteins, AmaEXLX1 (from Allomyces macrogynus) and ApuEXLX1 (from Aureobasidium pullulans), produced in Pichia pastoris. Despite retaining expansin-like structures, their low sequence identity (~22.5%) and contrasting isoelectric points (5.8 vs. 8.8) influenced their interaction with cellulose nanofibrils. AmaEXLX1 displayed stronger cellulose affinity, likely due to aromatic residues in its binding surface. Pretreating cellulose nanofibril films with either protein boosted the initial hydrolysis rate by endoglucanase Cel7B—highlighting their potential to enhance enzymatic cellulose breakdown.
https://doi.org/10.1016/j.crbiot.2025.100296
Together, these studies illuminate how structural features and phylogenetic origin shape the substrate targeting and functional efficacy of fungal expansin-like proteins—advancing biomolecular strategies for more efficient biomass conversion.
Great work from our team in Aalto!
