title: Characterization and functional analyses of the chitinase-encoding genes in the nematode-trapping fungus Arthrobotrys oligospora.
abstract: Nematode-trapping fungi can secrete many extracellular hydrolytic enzymes such as serine proteases and chitinases to digest and penetrate nematode/egg-cuticles. However, little is known about the structure and function of chitinases in these fungi. In this study, 16 ORFs encoding putative chitinases, which all belong to glycoside hydrolase (GH) family 18, were identified from the Arthrobotrys oligospora genome. Bioinformatics analyses showed that these 16 putative chitinases differ in their functional domains, molecular weights and pI. Phylogenetic analysis grouped these A. oligospora chitinases into four clades: clades I, II, III and IV, respectively, including an A. oligospora-specific subclade (Clade IV-B) that contained high-molecular weight chitinases (≥100 kDa). Transcriptional analysis of A. oligospora chitinases suggested that the expression of most chitinases was repressed by carbon starvation, and all chitinases were up-regulated under nitrogen starvation. However, chitinase AO-190 was up-regulated under carbon and/or nitrogen starvation. Moreover, several chitinases (such as AO-59, AO-190 and AO-801) were up-regulated in the presence of chitinous substrates or a plant pathogenic fungus, indicating that they could play a role in biocontrol applications of A. oligospora. Our results provided a basis for further understanding the functions, diversities and evolutionary relationships between chitinase genes in nematode-trapping fungi.
authors: Laboratory for Conservation and Utilization of Bio-Resources, and Key Laboratory of Microbial Diversity in Southwest China, Ministry of Education, Yunnan University, Kunming 650091, People's Republic of China. jinkuiyun@yahoo.com.cn
authors: Jinkui
authors: J
authors: Yang
authors: Yan
authors: Y
authors: Yu
authors: Juan
authors: J
authors: Li
authors: Wei
authors: W
authors: Zhu
authors: Zongyi
authors: Z
authors: Geng
authors: Dewei
authors: D
authors: Jiang
authors: Yunchuan
authors: Y
authors: Wang
authors: Ke-Qin
authors: KQ
authors: Zhang
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001203:Ascomycota / Q000201:enzymology* / Q000235:genetics* / Q000502:physiology; D002688:Chitinases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D005800:Genes, Fungal; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009348:Nematoda / Q000382:microbiology; D016366:Open Reading Frames; D010802:Phylogeny; D017434:Protein Structure, Tertiary; D014158:Transcription, Genetic
chemical_list: D005656:Fungal Proteins; D002688:Chitinases