Fitz Gerald S Silao, Valerie Diane Valeriano, Erika Uddström, Emilie Falconer, Per O Ljungdahl
{"title":"控制白念珠菌依赖氨基酸进行环境碱化的机制多种多样。","authors":"Fitz Gerald S Silao, Valerie Diane Valeriano, Erika Uddström, Emilie Falconer, Per O Ljungdahl","doi":"10.1111/mmi.15216","DOIUrl":null,"url":null,"abstract":"<p><p>Candida albicans has the capacity to neutralize acidic growth environments by releasing ammonia derived from the catabolism of amino acids. The molecular components underlying alkalization and its physiological significance remain poorly understood. Here, we present an integrative model with the cytosolic NAD<sup>+</sup>-dependent glutamate dehydrogenase (Gdh2) as the principal ammonia-generating component. We show that alkalization is dependent on the SPS-sensor-regulated transcription factor STP2 and the proline-responsive activator Put3. These factors function in parallel to derepress GDH2 and the two proline catabolic enzymes PUT1 and PUT2. Consistently, a double mutant lacking STP2 and PUT3 exhibits a severe alkalization defect that nearly phenocopies that of a gdh2-/- strain. Alkalization is dependent on mitochondrial activity and in wild-type cells occurs as long as the conditions permit respiratory growth. Strikingly, Gdh2 levels decrease and cells transiently extrude glutamate as the environment becomes more alkaline. Together, these processes constitute a rudimentary regulatory system that counters and limits the negative effects associated with ammonia generation. These findings align with Gdh2 being dispensable for virulence, and based on a whole human blood virulence assay, the same is true for C. glabrata and C. auris. Using a transwell co-culture system, we observed that the growth and proliferation of Lactobacillus crispatus, a common component of the acidic vaginal microenvironment and a potent antagonist of C. albicans, is unaffected by fungal-induced alkalization. Consequently, although Candida spp. can alkalinize their growth environments, other fungal-associated processes are more critical in promoting dysbiosis and virulent fungal growth.</p>","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":null,"pages":null},"PeriodicalIF":2.6000,"publicationDate":"2024-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Diverse mechanisms control amino acid-dependent environmental alkalization by Candida albicans.\",\"authors\":\"Fitz Gerald S Silao, Valerie Diane Valeriano, Erika Uddström, Emilie Falconer, Per O Ljungdahl\",\"doi\":\"10.1111/mmi.15216\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p><p>Candida albicans has the capacity to neutralize acidic growth environments by releasing ammonia derived from the catabolism of amino acids. The molecular components underlying alkalization and its physiological significance remain poorly understood. Here, we present an integrative model with the cytosolic NAD<sup>+</sup>-dependent glutamate dehydrogenase (Gdh2) as the principal ammonia-generating component. We show that alkalization is dependent on the SPS-sensor-regulated transcription factor STP2 and the proline-responsive activator Put3. These factors function in parallel to derepress GDH2 and the two proline catabolic enzymes PUT1 and PUT2. Consistently, a double mutant lacking STP2 and PUT3 exhibits a severe alkalization defect that nearly phenocopies that of a gdh2-/- strain. Alkalization is dependent on mitochondrial activity and in wild-type cells occurs as long as the conditions permit respiratory growth. Strikingly, Gdh2 levels decrease and cells transiently extrude glutamate as the environment becomes more alkaline. Together, these processes constitute a rudimentary regulatory system that counters and limits the negative effects associated with ammonia generation. These findings align with Gdh2 being dispensable for virulence, and based on a whole human blood virulence assay, the same is true for C. glabrata and C. auris. Using a transwell co-culture system, we observed that the growth and proliferation of Lactobacillus crispatus, a common component of the acidic vaginal microenvironment and a potent antagonist of C. albicans, is unaffected by fungal-induced alkalization. Consequently, although Candida spp. can alkalinize their growth environments, other fungal-associated processes are more critical in promoting dysbiosis and virulent fungal growth.</p>\",\"PeriodicalId\":19006,\"journal\":{\"name\":\"Molecular Microbiology\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":2.6000,\"publicationDate\":\"2024-04-01\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Molecular Microbiology\",\"FirstCategoryId\":\"99\",\"ListUrlMain\":\"https://doi.org/10.1111/mmi.15216\",\"RegionNum\":2,\"RegionCategory\":\"生物学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"2024/1/4 0:00:00\",\"PubModel\":\"Epub\",\"JCR\":\"Q3\",\"JCRName\":\"BIOCHEMISTRY & MOLECULAR BIOLOGY\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Molecular Microbiology","FirstCategoryId":"99","ListUrlMain":"https://doi.org/10.1111/mmi.15216","RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"2024/1/4 0:00:00","PubModel":"Epub","JCR":"Q3","JCRName":"BIOCHEMISTRY & MOLECULAR BIOLOGY","Score":null,"Total":0}
Diverse mechanisms control amino acid-dependent environmental alkalization by Candida albicans.
Candida albicans has the capacity to neutralize acidic growth environments by releasing ammonia derived from the catabolism of amino acids. The molecular components underlying alkalization and its physiological significance remain poorly understood. Here, we present an integrative model with the cytosolic NAD+-dependent glutamate dehydrogenase (Gdh2) as the principal ammonia-generating component. We show that alkalization is dependent on the SPS-sensor-regulated transcription factor STP2 and the proline-responsive activator Put3. These factors function in parallel to derepress GDH2 and the two proline catabolic enzymes PUT1 and PUT2. Consistently, a double mutant lacking STP2 and PUT3 exhibits a severe alkalization defect that nearly phenocopies that of a gdh2-/- strain. Alkalization is dependent on mitochondrial activity and in wild-type cells occurs as long as the conditions permit respiratory growth. Strikingly, Gdh2 levels decrease and cells transiently extrude glutamate as the environment becomes more alkaline. Together, these processes constitute a rudimentary regulatory system that counters and limits the negative effects associated with ammonia generation. These findings align with Gdh2 being dispensable for virulence, and based on a whole human blood virulence assay, the same is true for C. glabrata and C. auris. Using a transwell co-culture system, we observed that the growth and proliferation of Lactobacillus crispatus, a common component of the acidic vaginal microenvironment and a potent antagonist of C. albicans, is unaffected by fungal-induced alkalization. Consequently, although Candida spp. can alkalinize their growth environments, other fungal-associated processes are more critical in promoting dysbiosis and virulent fungal growth.
期刊介绍:
Molecular Microbiology, the leading primary journal in the microbial sciences, publishes molecular studies of Bacteria, Archaea, eukaryotic microorganisms, and their viruses.
Research papers should lead to a deeper understanding of the molecular principles underlying basic physiological processes or mechanisms. Appropriate topics include gene expression and regulation, pathogenicity and virulence, physiology and metabolism, synthesis of macromolecules (proteins, nucleic acids, lipids, polysaccharides, etc), cell biology and subcellular organization, membrane biogenesis and function, traffic and transport, cell-cell communication and signalling pathways, evolution and gene transfer. Articles focused on host responses (cellular or immunological) to pathogens or on microbial ecology should be directed to our sister journals Cellular Microbiology and Environmental Microbiology, respectively.