title: Genomic analyses and transcriptional profiles of the glycoside hydrolase family 18 genes of the entomopathogenic fungus Metarhizium anisopliae.
abstract: Fungal chitin metabolism involves diverse processes such as metabolically active cell wall maintenance, basic nutrition, and different aspects of virulence. Chitinases are enzymes belonging to the glycoside hydrolase family 18 (GH18) and 19 (GH19) and are responsible for the hydrolysis of β-1,4-linkages in chitin. This linear homopolymer of N-acetyl-β-D-glucosamine is an essential constituent of fungal cell walls and arthropod exoskeletons. Several chitinases have been directly implicated in structural, morphogenetic, autolytic and nutritional activities of fungal cells. In the entomopathogen Metarhizium anisopliae, chitinases are also involved in virulence. Filamentous fungi genomes exhibit a higher number of chitinase-coding genes than bacteria or yeasts. The survey performed in the M. anisopliae genome has successfully identified 24 genes belonging to glycoside hydrolase family 18, including three previously experimentally determined chitinase-coding genes named chit1, chi2 and chi3. These putative chitinases were classified based on domain organization and phylogenetic analysis into the previously described A, B and C chitinase subgroups, and into a new subgroup D. Moreover, three GH18 proteins could be classified as putative endo-N-acetyl-β-D-glucosaminidases, enzymes that are associated with deglycosylation and were therefore assigned to a new subgroup E. The transcriptional profile of the GH18 genes was evaluated by qPCR with RNA extracted from eight culture conditions, representing different stages of development or different nutritional states. The transcripts from the GH18 genes were detected in at least one of the different M. anisopliae developmental stages, thus validating the proposed genes. Moreover, not all members from the same chitinase subgroup presented equal patterns of transcript expression under the eight distinct conditions studied. The determination of M. anisopliae chitinases and ENGases and a more detailed study concerning the enzymes' roles in morphological or nutritional functions will allow comprehensive insights into the chitinolytic potential of this highly infective entomopathogenic fungus.
authors.affiliation: Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
authors.forename: Ângela
authors.initials: Â
authors.lastname: Junges
authors.affiliation: Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
authors.forename: Juliano Tomazzoni
authors.initials: JT
authors.lastname: Boldo
authors.affiliation: Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
authors.forename: Bárbara Kunzler
authors.initials: BK
authors.lastname: Souza
authors.affiliation: Laboratório Nacional de Computação Científica, Petrópolis, Brazil.
authors.forename: Rafael Lucas Muniz
authors.initials: RL
authors.lastname: Guedes
authors.affiliation: Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
authors.forename: Nicolau
authors.initials: N
authors.lastname: Sbaraini
authors.affiliation: Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
authors.forename: Lívia
authors.initials: L
authors.lastname: Kmetzsch
authors.affiliation: Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
authors.forename: Claudia Elizabeth
authors.initials: CE
authors.lastname: Thompson
authors.affiliation: Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
authors.forename: Charley Christian
authors.initials: CC
authors.lastname: Staats
authors.affiliation: Laboratório Nacional de Computação Científica, Petrópolis, Brazil.
authors.forename: Luis Gonzaga Paula
authors.initials: LG
authors.lastname: de Almeida
authors.affiliation: Laboratório Nacional de Computação Científica, Petrópolis, Brazil.
authors.forename: Ana Tereza Ribeiro
authors.initials: AT
authors.lastname: de Vasconcelos
authors.affiliation: Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
authors.forename: Marilene Henning
authors.initials: MH
authors.lastname: Vainstein
authors.affiliation: Centro de Biotecnologia, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
authors.forename: Augusto
authors.initials: A
authors.lastname: Schrank
mesh_terms: D002688:Chitinases / Q000235:genetics* / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism; D016681:Genome, Fungal; D052981:Metarhizium / Q000201:enzymology / Q000235:genetics*; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D014158:Transcription, Genetic; D059467:Transcriptome
chemical_list: D005656:Fungal Proteins; D002688:Chitinases