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Infection and Immunity, October 2009, p. 4584-4596, Vol. 77, No. 10
0019-9567/09/$08.00+0 doi:10.1128/IAI.00565-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.
The Trehalose Synthesis Pathway Is an Integral Part of the Virulence Composite for Cryptococcus gattii
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Popchai Ngamskulrungroj,1,2,3
Uwe Himmelreich,4
Julia A. Breger,5
Christabel Wilson,6
Methee Chayakulkeeree,1,3,6
Mark B. Krockenberger,7
Richard Malik,7
Heide-Marie Daniel,8
Dena Toffaletti,1
Julianne T. Djordjevic,6
Eleftherios Mylonakis,5
Wieland Meyer,2 and
John R. Perfect1*
Department of Medicine, Duke University Medical Center, Durham, North Carolina,1 Molecular Mycology Research Laboratory, Centre for Infectious Diseases and Microbiology, Westmead Millennium Institute, University of Sydney at Westmead Hospital, Westmead, New South Wales, Australia,2 Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand,3 Biomedical NMR Unit/MoSAIC, Faculty of Medicine, Katholieke Universiteit Leuven, Leuven, Belgium,4 Massachusetts General Hospital, Boston, Massachusetts,5 Fungal Pathogenesis Research Group, Centre for Infectious Diseases and Microbiology, Westmead Millennium Institute, Westmead Hospital, Westmead, New South Wales, Australia,6 Faculty of Veterinary Science, University of Sydney, Camperdown, New South Wales, Australia,7 Mycothèque de l'Université Catholique de Louvain, Louvain-la-Neuve, Belgium8
Received 20 May 2009/ Returned for modification 20 June 2009/ Accepted 29 July 2009
The trehalose pathway is essential for stress tolerance and virulence in fungi. We investigated the importance of this pathway for virulence of the pathogenic yeast Cryptococcus gattii using the highly virulent Vancouver Island, Canada, outbreak strain R265. Three genes putatively involved in trehalose biosynthesis, TPS1 (trehalose-6-phosphate [T6P] synthase) and TPS2 (T6P phosphatase), and degradation, NTH1 (neutral trehalose), were deleted in this strain, creating the R265tps1
, R265tps2, and R265nth1 mutants. As in Cryptococcus neoformans, cellular trehalose was reduced in the R265tps1 and R265tps2 mutants, which could not grow and died, respectively, at 37°C on yeast extract-peptone-dextrose agar, suggesting that T6P accumulation in R265tps2 is directly toxic. Characterizations of the cryptococcal hexokinases and trehalose mutants support their linkage to the control of glycolysis in this species. However, unlike C. neoformans, the C. gattii R265tps1 mutant demonstrated, in addition, defects in melanin and capsule production, supporting an influence of T6P on these virulence pathways. Attenuated virulence of the R265tps1 mutant was not due solely to its 37°C growth defect, as shown in worm studies and confirmed by suppressor mutants. Furthermore, an intact trehalose pathway controls protein secretion, mating, and cell wall integrity in C. gattii. Thus, the trehalose synthesis pathway plays a central role in the virulence composites of C. gattii through multiple mechanisms. Deletion of NTH1 had no effect on virulence, but inactivation of the synthesis genes, TPS1 and TPS2, has profound effects on survival of C. gattii in the invertebrate and mammalian hosts. These results highlight the central importance of this pathway in the virulence composites of both pathogenic cryptococcal species.
* Corresponding author. Mailing address: Box 102359, Duke University Medical Center, Durham, NC 27710. Phone: (919) 684-4016. Fax: (919) 684-8902. E-mail: perfe001{at}mc.duke.edu
Published ahead of print on 3 August 2009.
Supplemental material for this article may be found at http://iai.asm.org/.
Infection and Immunity, October 2009, p. 4584-4596, Vol. 77, No. 10
0019-9567/09/$08.00+0 doi:10.1128/IAI.00565-09
Copyright © 2009, American Society for Microbiology. All Rights Reserved.
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