Trichoderma harzianum lipolyitic enzymes - a contribution
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abstract
Trichoderma sp. has been related to the mycoparasitism process due to an extraordinary range of cell-wall degrading enzymes (CWDE): chitinases, β-1,3 and β-1,6 glucanases, celulases and proteases. However, the role of lipases and carboxylesterases in this process is less known, although lipids were up to 3% of fungal CW (Feofilova, 2010). According to Silva et al. (2009) and Lopes et al. (2012), in experiments involving T. reesei and Pythium ultimum, it seems that lipases are implicated in mycoparasitism and are secreted in a phytopathogen-dependent manner, as they, like most of the CWDE already described, are inducible by substrate. Here we present our contribution to the knowledge of T. harzianum T34 lipolytic enzymes (EC 3.1.1).
Some ESTs of a T. harzianum cDNA library coming from the EU-funded TRICHOEST project and obtained under mycoparasitism, nutritional stress and plant interaction conditions were BLAST screened, and two of them were completed by HE-TAIL PCR (Michiels et al., 2003) and sequenced, showing significant homology with EC 3.1.1 enzymes.
The Lip1 gene, with a 1677 bp ORF and accessed in EMBL database (AM180877.1), codifies a deduced 56,3 kDa protein of 532 amino acids (B0B099_TRIHA), a carboxylesterase_B_1 (EC 3.1.1.1; PROSITE PS00122, E-value 2,9 e-128), with affinity for short chain fatty acids (C<10) and soluble substrates. The Lip2 gene (AM774154.1) has a 1215 bp ORF and codifies a deduced 44 kDa protein (B7ZET5_TRIHA), a triacylglycerol lipase (EC 3.1.1.3; Pfam PF01764), with affinity for long chain fatty acids (C>10) and acting on insoluble substrates.
These results shows that T. harzianum has different kind of lipolytic enzymes that could have synergistic effects with other hydrolytic enzymes in the process of mycoparasitism, although its role is not so well-known.
