title: The Role of Amino Acid Permeases and Tryptophan Biosynthesis in Cryptococcus neoformans Survival.
abstract: Metabolic diversity is an important factor during microbial adaptation to different environments. Among metabolic processes, amino acid biosynthesis has been demonstrated to be relevant for survival for many microbial pathogens, whereas the association between pathogenesis and amino acid uptake and recycling are less well-established. Cryptococcus neoformans is an opportunistic fungal pathogen with many habitats. As a result, it faces frequent metabolic shifts and challenges during its life cycle. Here we studied the C. neoformans tryptophan biosynthetic pathway and found that the pathway is essential. RNAi indicated that interruptions in the biosynthetic pathway render strains inviable. However, auxotroph complementation can be partially achieved by tryptophan uptake when a non preferred nitrogen source and lower growth temperature are applied, suggesting that amino acid permeases may be the target of nitrogen catabolism repression (NCR). We used bioinformatics to search for amino acid permeases in the C. neoformans and found eight potential global permeases (AAP1 to AAP8). The transcriptional profile of them revealed that they are subjected to regulatory mechanisms which are known to respond to nutritional status in other fungi, such as (i) quality of nitrogen (Nitrogen Catabolism Repression, NCR) and carbon sources (Carbon Catabolism Repression, CCR), (ii) amino acid availability in the extracellular environment (SPS-sensing) and (iii) nutritional deprivation (Global Amino Acid Control, GAAC). This study shows that C. neoformans has fewer amino acid permeases than other model yeasts, and that these proteins may be subjected to complex regulatory mechanisms. Our data suggest that the C. neoformans tryptophan biosynthetic pathway is an excellent pharmacological target. Furthermore, inhibitors of this pathway cause Cryptococcus growth arrest in vitro.
authors.affiliation: Departamento de Ciências Biológicas, Instituto de Ciências Ambientais, Químicas e Farmacêuticas, Universidade Federal de São Paulo, Campus Diadema, Laboratório de Interações Microbianas (Laboratory 29), Rua Arthur Ridel, 275, 09972-270, Bairro Eldorado, Diadema, SP, Brazil; Universidade de São Paulo, Avenida Prof. Lineu Prestes, 2415 Edifício ICB - III, Cidade Universitária, CEP 05508-900, São Paulo, SP, Brazil.
authors.forename: João Daniel Santos
authors.initials: JD
authors.lastname: Fernandes
authors.affiliation: Departamento de Ciências Biológicas, Instituto de Ciências Ambientais, Químicas e Farmacêuticas, Universidade Federal de São Paulo, Campus Diadema, Laboratório de Interações Microbianas (Laboratory 29), Rua Arthur Ridel, 275, 09972-270, Bairro Eldorado, Diadema, SP, Brazil.
authors.forename: Kevin
authors.initials: K
authors.lastname: Martho
authors.affiliation: Departamento de Ciências Biológicas, Instituto de Ciências Ambientais, Químicas e Farmacêuticas, Universidade Federal de São Paulo, Campus Diadema, Laboratório de Interações Microbianas (Laboratory 29), Rua Arthur Ridel, 275, 09972-270, Bairro Eldorado, Diadema, SP, Brazil.
authors.forename: Veridiana
authors.initials: V
authors.lastname: Tofik
authors.affiliation: Departamento de Ciências Biológicas, Instituto de Ciências Ambientais, Químicas e Farmacêuticas, Universidade Federal de São Paulo, Campus Diadema, Laboratório de Interações Microbianas (Laboratory 29), Rua Arthur Ridel, 275, 09972-270, Bairro Eldorado, Diadema, SP, Brazil.
authors.forename: Marcelo A
authors.initials: MA
authors.lastname: Vallim
authors.affiliation: Departamento de Ciências Biológicas, Instituto de Ciências Ambientais, Químicas e Farmacêuticas, Universidade Federal de São Paulo, Campus Diadema, Laboratório de Interações Microbianas (Laboratory 29), Rua Arthur Ridel, 275, 09972-270, Bairro Eldorado, Diadema, SP, Brazil.
authors.forename: Renata C
authors.initials: RC
authors.lastname: Pascon
mesh_terms: D026905:Amino Acid Transport Systems / Q000235:genetics / Q000378:metabolism*; D053898:Biosynthetic Pathways / Q000187:drug effects / Q000235:genetics; D003455:Cryptococcus neoformans / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D017353:Gene Deletion; D020869:Gene Expression Profiling; D015966:Gene Expression Regulation, Fungal / Q000187:drug effects; D020043:Genes, Essential; D005800:Genes, Fungal; D008826:Microbial Sensitivity Tests; D050296:Microbial Viability / Q000187:drug effects; D009154:Mutation / Q000235:genetics; D009584:Nitrogen / Q000494:pharmacology; D010641:Phenotype; D034622:RNA Interference / Q000187:drug effects; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects; D014364:Tryptophan / Q000096:biosynthesis*
chemical_list: D026905:Amino Acid Transport Systems; D005656:Fungal Proteins; D014364:Tryptophan; D009584:Nitrogen