Open AccessDeciphering the role of the chitin synthase families 1 and 2 in the in vivo and in vitro growth of A spergillus fumigatus by multiple gene targeting deletion
Author(s) -
Muszkieta Laetitia,
Aimanianda Vishukumar,
Mellado Emilia,
Gribaldo Simonetta,
AlcàzarFuoli Laura,
Szewczyk Edyta,
Prevost MarieChristine,
Latgé JeanPaul
Publication year - 2014
Publication title -
cellular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.542
H-Index - 138
eISSN - 1462-5822
pISSN - 1462-5814
DOI - 10.1111/cmi.12326
Subject(s) - conidiation , mutant , biology , virulence , mycelium , aspergillus fumigatus , chitin synthase , chitin , gene , phenotype , microbiology and biotechnology , gene family , genetics , biochemistry , gene expression , botany , chitosan
Summary Although chitin is an essential component of the fungal cell wall ( CW ), its biosynthesis and role in virulence is poorly understood. In A spergillus fumigatus , there are eight chitin synthase ( CHS ) genes belonging to two families CHSA‐C , CHSG in family 1 and CHSF , CHSD , CSMA , CSMB in family 2). To understand the function of these CHS genes, their single and multiple deletions were performed using β‐rec/six system to be able to delete all genes within each family (up to a quadruple Δ chsA/C/B/G mutant in family 1 and a quadruple Δ csmA/csmB/F/D mutant in family 2). Radial growth, conidiation, mycelial/conidial morphology, CW polysaccharide content, Chs ‐activity, susceptibility to antifungal molecules and pathogenicity in experimental animal aspergillosis were analysed for all the mutants. Among the family 1 CHS , Δ chsA , Δ chsB and Δ chsC mutants showed limited impact on chitin synthesis. In contrast, there was reduced conidiation, altered mycelial morphotype and reduced growth and Chs ‐activity in the Δ chsG and Δ chsA/C/B/G mutants. In spite of this altered phenotype, these two mutants were as virulent as the parental strain in the experimental aspergillosis models. Among family 2 CHS , phenotypic defects mainly resulted from the CSMA deletion. Despite significant morphological mycelial and conidial growth phenotypes in the quadruple Δ csmA/csmB/F/D mutant, the chitin content was poorly affected by gene deletions in this family. However, the entire mycelial cell wall structure was disorganized in the family 2 mutants that may be related to the reduced pathogenicity of the quadruple Δ csmA/csmB/F/D mutant strain compared to the parental strain, in vivo . Deletion of the genes encompassing the two families (Δ csmA/csmB/F/G ) showed that in spite of being originated from an ancient divergence of fungi, these two families work cooperatively to synthesize chitin in A . fumigatus and demonstrate the essentiality of chitin biosynthesis for vegetative growth, resistance to antifungal drugs, and virulence of this filamentous fungus.