Cryptococcus neoformans Kin1 protein kinase homologue, identified through a Caenorhabditis elegans screen, promotes virulence in mammals.
Cryptococcal infections are a global cause of significant morbidity and mortality. Recent studies support the hypothesis that virulence of Cryptococcus neoformans may have evolved via survival selection in environmental hosts, such as amoebae and free-living nematodes. We used killing of the nematode Caenorhabditis elegans by C. neoformans as an assay to screen a library of random C. neoformans insertion mutants. Of 350 mutants tested, seven were identified with attenuated virulence that persisted after crossing the mutation back into a wild-type strain. Genetic analysis of one strain revealed an insertion in a gene homologous to Saccharomyces cerevisiae KIN1, which encodes a serine/threonine protein kinase. C. neoformans kin1 mutants exhibited significant defects in virulence in murine inhalation and haematogenous infection models and displayed increased binding to alveolar and peritoneal macrophages. The kin1 mutant phenotypes were complemented by the wild-type KIN1 gene. These findings show that the C. neoformans Kin1 kinase homologue is required for full virulence in disparate hosts and that C. elegans can be used as a substitute host to identify novel factors involved in fungal pathogenesis in mammals.
Division of Infectious Diseases, Massachusetts General Hospital, Boston, MA 02114, USA.
Eleftherios
E
Mylonakis
Alexander
A
Idnurm
Roberto
R
Moreno
Joseph
J
El Khoury
James B
JB
Rottman
Frederick M
FM
Ausubel
Joseph
J
Heitman
Stephen B
SB
Calderwood
D000818:Animals; D001681:Biological Assay / Q000379:methods*; D001921:Brain / Q000382:microbiology / Q000473:pathology; D017173:Caenorhabditis elegans / Q000378:metabolism / Q000382:microbiology*; D002478:Cells, Cultured; D003453:Cryptococcosis / Q000473:pathology; D003455:Cryptococcus neoformans / Q000201:enzymology* / Q000235:genetics / Q000472:pathogenicity / Q000648:ultrastructure; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D041981:Gastrointestinal Tract / Q000382:microbiology; D006801:Humans; D008264:Macrophages / Q000166:cytology / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D010587:Phagocytosis; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D011650:Pulmonary Alveoli / Q000382:microbiology / Q000473:pathology; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D015996:Survival Rate
D005656:Fungal Proteins; D010750:Phosphoproteins; D029701:Saccharomyces cerevisiae Proteins; C490209:KIN1 protein, S cerevisiae; D017346:Protein Serine-Threonine Kinases