title: A novel L-amino acid oxidase from Trichoderma harzianum ETS 323 associated with antagonism of Rhizoctonia solani.
abstract: Trichoderma spp. are used as biocontrol agents against phytopathogens such as Rhizoctonia solani, but their biocontrol mechanisms are poorly understood. A novel L-amino oxidase (Th-LAAO) was identified from the extracellular proteins of Trichoderma harzianum ETS 323. Here, we show a FAD-binding glycoprotein with the best substrate specificity constant for L-phenylalanine. Although the amino acid sequence of Th-LAAO revealed limited homology (16-24%) to other LAAO members, a highly conserved FAD-binding motif was identified in the N-terminus. Th-LAAO was shown to be a homodimeric protein, but the monomeric form was predominant when grown in the presence of deactivated Rhizoctonia solani. Furthermore, in vitro assays demonstrated that Th-LAAO had an antagonistic effect against Rhizoctonia solani and a stimulatory one on hyphal density and sporulation in T. harzianum ETS 323. These findings further our understanding of T. harzianum as a biocontrol agent and provide insight into the biological function of l-amino acid oxidase.
authors: Institute of Medical Science, Tzu Chi University, Hualien, Taiwan, ROC.
authors: Chia-Ann
authors: CA
authors: Yang
authors: Chi-Hua
authors: CH
authors: Cheng
authors: Chaur-Tsuen
authors: CT
authors: Lo
authors: Shu-Ying
authors: SY
authors: Liu
authors: Jeng-Woei
authors: JW
authors: Lee
authors: Kou-Cheng
authors: KC
authors: Peng
mesh_terms: D000595:Amino Acid Sequence; D000898:Antibiosis; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D050830:L-Amino Acid Oxidase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D012232:Rhizoctonia / Q000502:physiology*; D016415:Sequence Alignment; D013379:Substrate Specificity; D014242:Trichoderma / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics / Q000502:physiology*
chemical_list: D005656:Fungal Proteins; D050830:L-Amino Acid Oxidase