title: Metabolic flux analysis of the halophilic archaeon Haladaptatus paucihalophilus.
abstract: This work reports the (13)C-assisted metabolic flux analysis of Haladaptatus paucihalophilus, a halophilic archaeon possessing an intriguing osmoadaption mechanism. We showed that the carbon flow is through the oxidative tricarboxylic acid (TCA) cycle whereas the reductive TCA cycle is not operative in H. paucihalophilus. In addition, both threonine and the citramalate pathways contribute to isoleucine biosynthesis, whereas lysine is synthesized through the diaminopimelate pathway and not through the α-aminoadipate pathway. Unexpected, the labeling patterns of glycine from the cells grown on [1-(13)C]pyruvate and [2-(13)C]pyruvate suggest that, unlike all the organisms investigated so far, in which glycine is produced exclusively from the serine hydroxymethyltransferase (SHMT) pathway, glycine biosynthesis in H. paucihalophilus involves different pathways including SHMT, threonine aldolase (TA) and the reverse reaction of glycine cleavage system (GCS), demonstrating for the first time that other pathways instead of SHMT can also make a significant contribution to the cellular glycine pool. Transcriptional analysis confirmed that both TA and GCS genes were transcribed in H. paucihalophilus, and the transcriptional level is independent of salt concentrations in the culture media. This study expands our understanding of amino acid biosynthesis and provides valuable insights into the metabolism of halophilic archaea.
authors.affiliation: Key Laboratory of Desert and Desertification, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou, 730000, China; Key Laboratory of Extreme Environmental Microbial Resources and Engineering, Gansu Province, Lanzhou, 730000, China.
authors.forename: Guangxiu
authors.initials: G
authors.lastname: Liu
authors.affiliation: Key Laboratory of Desert and Desertification, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou, 730000, China; Key Laboratory of Extreme Environmental Microbial Resources and Engineering, Gansu Province, Lanzhou, 730000, China.
authors.forename: Manxiao
authors.initials: M
authors.lastname: Zhang
authors.affiliation: Department of Chemistry, Fudan University, Shanghai, 200433, China.
authors.forename: Tianlu
authors.initials: T
authors.lastname: Mo
authors.affiliation: Key Laboratory of Combinatory Biosynthesis and Drug Discovery (Ministry of Education), School of Pharmaceutical Sciences, Wuhan University, Wuhan, 430071, China.
authors.forename: Lian
authors.initials: L
authors.lastname: He
authors.affiliation: Key Laboratory of Desert and Desertification, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou, 730000, China; Key Laboratory of Extreme Environmental Microbial Resources and Engineering, Gansu Province, Lanzhou, 730000, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Combinatory Biosynthesis and Drug Discovery (Ministry of Education), School of Pharmaceutical Sciences, Wuhan University, Wuhan, 430071, China. Electronic address: yu_yi@whu.edu.cn.
authors.forename: Yi
authors.initials: Y
authors.lastname: Yu
authors.affiliation: Department of Chemistry, Fudan University, Shanghai, 200433, China. Electronic address: qizhang@sioc.ac.cn.
authors.forename: Qi
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Desert and Desertification, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou, 730000, China; Key Laboratory of Extreme Environmental Microbial Resources and Engineering, Gansu Province, Lanzhou, 730000, China; Department of Chemistry, Fudan University, Shanghai, 200433, China. Electronic address: dingw@lzu.edu.cn.
authors.forename: Wei
authors.initials: W
authors.lastname: Ding
mesh_terms: D001105:Archaea / Q000378:metabolism*; D002952:Citric Acid Cycle; D014158:Transcription, Genetic
keywords: (13)C-assisted metabolism analysis; Glycine biosynthesis; Halophilic archaea; Isoleucine biosynthesis; Lysine biosynthesis