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Díaz-Pérez AL, Núñez C, Meza Carmen V, Campos-García J. The expression of the genes involved in leucine catabolism of Pseudomonas aeruginosa is controlled by the transcriptional regulator LiuR and by the CbrAB/Crc system. Res Microbiol 2018; 169:324-334. [PMID: 29787835 DOI: 10.1016/j.resmic.2018.05.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Revised: 05/09/2018] [Accepted: 05/15/2018] [Indexed: 12/29/2022]
Abstract
Pseudomonas aeruginosa metabolizes leucine through the leucine/isovalerate utilization pathway, whose enzymes are encoded in the liuRABCDE gene cluster (liu). In this study, we investigated the role of the LiuR protein in the liu cluster regulation. Our results indicated that liu expression is regulated at the transcriptional level by LiuR. Mobility shift assays using purified recombinant His-tagged LiuR showed that it was able to bind at the promoter region of liuR, in a dose-dependent manner. Results revealed that expression of the liu operon is subjected to carbon catabolite repression control (CCR); protein LiuD was strongly expressed in the presence of leucine, but it was repressed in the presence of glucose or succinate. Furthermore, this CCR control was dependent on LiuR as in the liuR- mutant the LiuD protein was strongly expressed in all the carbon sources tested. In agreement with this result, in the absence of the Crc protein, LiuD was expressed independently of the carbon source used, whereas in a cbrB- mutant its expression was severely impaired. The results indicated that the liu cluster is subjected to a coordinated transcriptional and translational regulation by the LiuR repressor and by the CbrAB/Crc system, respectively, in response to the available carbon source.
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Affiliation(s)
- Alma Laura Díaz-Pérez
- Laboratorio de Biotecnología Microbiana, Instituto de Investigaciones Químico Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Morelia, Michoacán, 58030, Mexico.
| | - Cinthia Núñez
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Col. Chamilpa, Cuernavaca, Morelos, 62210, Mexico.
| | - Victor Meza Carmen
- Laboratorio de Diferenciación Celular, Instituto de Investigaciones Químico Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Morelia, Michoacán, 58030, Mexico.
| | - Jesús Campos-García
- Laboratorio de Biotecnología Microbiana, Instituto de Investigaciones Químico Biológicas, Universidad Michoacana de San Nicolás de Hidalgo, Morelia, Michoacán, 58030, Mexico.
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Jurado AR, Huang CS, Zhang X, Zhou ZH, Tong L. Structure and substrate selectivity of the 750-kDa α6β6 holoenzyme of geranyl-CoA carboxylase. Nat Commun 2015; 6:8986. [PMID: 26593090 PMCID: PMC4673880 DOI: 10.1038/ncomms9986] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2015] [Accepted: 10/22/2015] [Indexed: 01/15/2023] Open
Abstract
Geranyl-CoA carboxylase (GCC) is essential for the growth of Pseudomonas organisms with geranic acid as the sole carbon source. GCC has the same domain organization and shares strong sequence conservation with the related biotin-dependent carboxylases 3-methylcrotonyl-CoA carboxylase (MCC) and propionyl-CoA carboxylase (PCC). Here we report the crystal structure of the 750-kDa α6β6 holoenzyme of GCC, which is similar to MCC but strikingly different from PCC. The structures provide evidence in support of two distinct lineages of biotin-dependent acyl-CoA carboxylases, one carboxylating the α carbon of a saturated organic acid and the other carboxylating the γ carbon of an α-β unsaturated acid. Structural differences in the active site region of GCC and MCC explain their distinct substrate preferences. Especially, a glycine residue in GCC is replaced by phenylalanine in MCC, which blocks access by the larger geranyl-CoA substrate. Mutation of this residue in the two enzymes can change their substrate preferences. The structures of the biotin-dependent carboxylases have revealed details of their function. Here, the authors describe the first structure of Pseudomonas geranyl-CoA carboxylase, and compare it with the previously characterised homologous 3-methylcrotonyl-CoA carboxylase.
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Affiliation(s)
- Ashley R Jurado
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
| | - Christine S Huang
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
| | - Xing Zhang
- California NanoSystems Institute, University of California, Los Angeles, California 90095, USA
| | - Z Hong Zhou
- California NanoSystems Institute, University of California, Los Angeles, California 90095, USA.,Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, California 90095, USA
| | - Liang Tong
- Department of Biological Sciences, Columbia University, New York, New York 10027, USA
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Ge F, Huang W, Chen Z, Zhang C, Xiong Q, Bowler C, Yang J, Xu J, Hu H. Methylcrotonyl-CoA Carboxylase Regulates Triacylglycerol Accumulation in the Model Diatom Phaeodactylum tricornutum. THE PLANT CELL 2014; 26:1681-1697. [PMID: 24769481 PMCID: PMC4036579 DOI: 10.1105/tpc.114.124982] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
The model marine diatom Phaeodactylum tricornutum can accumulate high levels of triacylglycerols (TAGs) under nitrogen depletion and has attracted increasing attention as a potential system for biofuel production. However, the molecular mechanisms involved in TAG accumulation in diatoms are largely unknown. Here, we employed a label-free quantitative proteomics approach to estimate differences in protein abundance before and after TAG accumulation. We identified a total of 1193 proteins, 258 of which were significantly altered during TAG accumulation. Data analysis revealed major changes in proteins involved in branched-chain amino acid (BCAA) catabolic processes, glycolysis, and lipid metabolic processes. Subsequent quantitative RT-PCR and protein gel blot analysis confirmed that four genes associated with BCAA degradation were significantly upregulated at both the mRNA and protein levels during TAG accumulation. The most significantly upregulated gene, encoding the β-subunit of methylcrotonyl-CoA carboxylase (MCC2), was selected for further functional studies. Inhibition of MCC2 expression by RNA interference disturbed the flux of carbon (mainly in the form of leucine) toward BCAA degradation, resulting in decreased TAG accumulation. MCC2 inhibition also gave rise to incomplete utilization of nitrogen, thus lowering biomass during the stationary growth phase. These findings help elucidate the molecular and metabolic mechanisms leading to increased lipid production in diatoms.
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Affiliation(s)
- Feng Ge
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Weichao Huang
- Diatom Biology Group, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Zhuo Chen
- Diatom Biology Group, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Chunye Zhang
- Diatom Biology Group, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Qian Xiong
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Chris Bowler
- Environmental and Evolutionary Genomics Section, Institut de Biologie de l'Ecole Normale Supérieure, Centre National de la Recherche Scientifique, Unité Mixte de Recherche 8197, Institut National de la Santé et de la Recherche Médicale U1024, Ecole Normale Supérieure, 75230 Paris cedex 05, France
| | - Juan Yang
- Diatom Biology Group, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Jin Xu
- Diatom Biology Group, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
| | - Hanhua Hu
- Key Laboratory of Algal Biology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China Diatom Biology Group, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, China
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