title: Role of the yakA gene in morphogenesis and stress response in Penicillium marneffei.
abstract: Penicillium marneffei is a thermally dimorphic fungus and a highly significant pathogen of immunocompromised individuals living in or having travelled in south-east Asia. At 25 °C, P. marneffei grows filamentously. Under the appropriate conditions, these filaments (hyphae) produce conidiophores bearing chains of conidia. Yet, when incubated at 37 °C, or upon infecting host tissue, P. marneffei grows as a yeast that divides by binary fission. Previously, an Agrobacterium-mediated transformation system was used to randomly mutagenize P. marneffei, resulting in the isolation of a mutant defective in normal patterns of morphogenesis and conidiogenesis. The interrupted gene was identified as yakA. In the current study, we demonstrate that the yakA mutant produced fewer conidia at 25 °C than the wild-type and a complemented strain. In addition, disruption of the yakA gene resulted in early conidial germination and perturbation of cell wall integrity. The yakA mutant exhibited abnormal chitin distribution while growing at 25 °C, but not at 37 °C. Interestingly, at both temperatures, the yakA mutant possessed increased chitin content, which was accompanied by amplified transcription of two chitin synthase genes, chsB and chsG. Moreover, the expression of yakA was induced during post-exponential-phase growth as well as by heat shock. Thus, yakA is required for normal patterns of development, cell wall integrity, chitin deposition, appropriate chs expression and heat stress response in P. marneffei.
authors.affiliation: Center for Applied Chemical Biology and Department of Biological Sciences, Youngstown State University, One University Plaza, Youngstown, OH 44555, USA.|Department of Microbiology, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand.
authors.forename: Sumanun
authors.initials: S
authors.lastname: Suwunnakorn
authors.affiliation: Center for Applied Chemical Biology and Department of Biological Sciences, Youngstown State University, One University Plaza, Youngstown, OH 44555, USA.
authors.forename: Chester R
authors.initials: CR
authors.lastname: Cooper
authors.affiliation: Division of Clinical Microbiology, Department of Medical Technology, School of Allied Health Sciences, University of Phayao, Phayao 56000, Thailand.
authors.forename: Aksarakorn
authors.initials: A
authors.lastname: Kummasook
authors.affiliation: Department of Microbiology, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand.
authors.forename: Nongnuch
authors.initials: N
authors.lastname: Vanittanakom
mesh_terms: D001692:Biological Transport / Q000528:radiation effects; D002686:Chitin / Q000378:metabolism; D017353:Gene Deletion; D005816:Genetic Complementation Test; D013172:Spores, Fungal / Q000254:growth & development; D013312:Stress, Physiological; D032901:Talaromyces / Q000166:cytology / Q000254:growth & development / Q000502:physiology* / Q000528:radiation effects*; D013696:Temperature
chemical_list: D002686:Chitin