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Olea-Ozuna RJ, Poggio S, Bergström E, Osorio A, Elufisan TO, Padilla-Gómez J, Martínez-Aguilar L, López-Lara IM, Thomas-Oates J, Geiger O. Genes required for phosphosphingolipid formation in Caulobacter crescentus contribute to bacterial virulence. PLoS Pathog 2024; 20:e1012401. [PMID: 39093898 PMCID: PMC11324152 DOI: 10.1371/journal.ppat.1012401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2024] [Revised: 08/14/2024] [Accepted: 07/08/2024] [Indexed: 08/04/2024] Open
Abstract
Sphingolipids are ubiquitous in membranes of eukaryotes and are associated with important cellular functions. Although sphingolipids occur scarcely in bacteria, for some of them they are essential and, in other bacteria, they contribute to fitness and stability of the outer membrane, such as in the well-studied α-proteobacterium Caulobacter crescentus. We previously defined five structural genes for ceramide synthesis in C. crescentus, among them the gene for serine palmitoyltransferase, the enzyme that catalyzes the committed step of sphingolipid biosynthesis. Other mutants affected in genes of this same genomic region show cofitness with a mutant deficient in serine palmitoyltransferase. Here we show that at least two phosphosphingolipids are produced in C. crescentus and that at least another six gene products are needed for the decoration of ceramide upon phosphosphingolipid formation. All eleven genes participating in phosphosphingolipid formation are also required in C. crescentus for membrane stability and for displaying sensitivity towards the antibiotic polymyxin B. The genes for the formation of complex phosphosphingolipids are also required for C. crescentus virulence on Galleria mellonella insect larvae.
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Affiliation(s)
- Roberto Jhonatan Olea-Ozuna
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Avenida Universidad s/n, Cuernavaca, Morelos, Mexico
| | - Sebastian Poggio
- Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Ed Bergström
- Centre of Excellence in Mass Spectrometry and Department of Chemistry, University of York, Heslington, York, United Kingdom
| | - Aurora Osorio
- Departamento de Biología Molecular y Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Temidayo Oluyomi Elufisan
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Avenida Universidad s/n, Cuernavaca, Morelos, Mexico
| | - Jonathan Padilla-Gómez
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Avenida Universidad s/n, Cuernavaca, Morelos, Mexico
| | - Lourdes Martínez-Aguilar
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Avenida Universidad s/n, Cuernavaca, Morelos, Mexico
| | - Isabel M. López-Lara
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Avenida Universidad s/n, Cuernavaca, Morelos, Mexico
| | - Jane Thomas-Oates
- Centre of Excellence in Mass Spectrometry and Department of Chemistry, University of York, Heslington, York, United Kingdom
| | - Otto Geiger
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Avenida Universidad s/n, Cuernavaca, Morelos, Mexico
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2
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Harvey DJ. Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update for 2021-2022. MASS SPECTROMETRY REVIEWS 2024. [PMID: 38925550 DOI: 10.1002/mas.21873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2023] [Revised: 02/05/2024] [Accepted: 02/12/2024] [Indexed: 06/28/2024]
Abstract
The use of matrix-assisted laser desorption/ionization (MALDI) mass spectrometry for the analysis of carbohydrates and glycoconjugates is a well-established technique and this review is the 12th update of the original article published in 1999 and brings coverage of the literature to the end of 2022. As with previous review, this review also includes a few papers that describe methods appropriate to analysis by MALDI, such as sample preparation, even though the ionization method is not MALDI. The review follows the same format as previous reviews. It is divided into three sections: (1) general aspects such as theory of the MALDI process, matrices, derivatization, MALDI imaging, fragmentation, quantification and the use of computer software for structural identification. (2) Applications to various structural types such as oligo- and polysaccharides, glycoproteins, glycolipids, glycosides and biopharmaceuticals, and (3) other general areas such as medicine, industrial processes, natural products and glycan synthesis where MALDI is extensively used. Much of the material relating to applications is presented in tabular form. MALDI is still an ideal technique for carbohydrate analysis, particularly in its ability to produce single ions from each analyte and advancements in the technique and range of applications show little sign of diminishing.
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Uchendu CG, Guan Z, Klein EA. Spatial organization of bacterial sphingolipid synthesis enzymes. J Biol Chem 2024; 300:107276. [PMID: 38588805 PMCID: PMC11087976 DOI: 10.1016/j.jbc.2024.107276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Revised: 03/16/2024] [Accepted: 04/02/2024] [Indexed: 04/10/2024] Open
Abstract
Sphingolipids are produced by nearly all eukaryotes where they play significant roles in cellular processes such as cell growth, division, programmed cell death, angiogenesis, and inflammation. While it was previously believed that sphingolipids were quite rare among bacteria, bioinformatic analysis of the recently identified bacterial sphingolipid synthesis genes suggests that these lipids are likely to be produced by a wide range of microbial species. The sphingolipid synthesis pathway consists of three critical enzymes. Serine palmitoyltransferase catalyzes the condensation of serine with palmitoyl-CoA (or palmitoyl-acyl carrier protein), ceramide synthase adds the second acyl chain, and a reductase reduces the ketone present on the long-chain base. While there is general agreement regarding the identity of these bacterial enzymes, the precise mechanism and order of chemical reactions for microbial sphingolipid synthesis is more ambiguous. Two mechanisms have been proposed. First, the synthesis pathway may follow the well characterized eukaryotic pathway in which the long-chain base is reduced prior to the addition of the second acyl chain. Alternatively, our previous work suggests that addition of the second acyl chain precedes the reduction of the long-chain base. To distinguish between these two models, we investigated the subcellular localization of these three key enzymes. We found that serine palmitoyltransferase and ceramide synthase are localized to the cytoplasm, whereas the ceramide reductase is in the periplasmic space. This is consistent with our previously proposed model wherein the second acyl chain is added in the cytoplasm prior to export to the periplasm where the lipid molecule is reduced.
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Affiliation(s)
- Chioma G Uchendu
- Center for Computational and Integrative Biology, Rutgers University-Camden, Camden, New Jersey, USA
| | - Ziqiang Guan
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina, USA
| | - Eric A Klein
- Center for Computational and Integrative Biology, Rutgers University-Camden, Camden, New Jersey, USA; Biology Department, Rutgers University-Camden, Camden, New Jersey, USA; Rutgers Center for Lipid Research, Rutgers University, New Brunswick, New Jersey, USA.
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Hummels KR. mSphere of Influence: Celebrating exceptions to the rule of lipid A essentiality. mSphere 2024; 9:e0063323. [PMID: 38421175 PMCID: PMC10964400 DOI: 10.1128/msphere.00633-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/02/2024] Open
Abstract
Kate Hummels works in the field of bacterial cell envelope biosynthesis and studies the regulation of the metabolic pathways needed to build the Gram-negative cell envelope. In this mSphere of Influence article, she reflects on how the papers "A penicillin-binding protein inhibits selection of colistin-resistant, lipopoligosaccharide-deficient Acinetobacter baumannii" by Boll et al. and "Caulobacter lipid A is conditionally dispensable in the absence of fur and in the presence of anionic sphingolipids" by Zik et al. made an impact on her by studying organisms that deviate from accepted norms to highlight the plethora of unanswered questions in cell envelope biology.
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VanOtterloo LM, Macias LA, Powers MJ, Brodbelt JS, Trent MS. Characterization of Acinetobacter baumannii core oligosaccharide synthesis reveals novel aspects of lipooligosaccharide assembly. mBio 2024; 15:e0301323. [PMID: 38349180 PMCID: PMC10936431 DOI: 10.1128/mbio.03013-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Accepted: 01/12/2024] [Indexed: 03/14/2024] Open
Abstract
A fundamental feature of Gram-negative bacteria is their outer membrane that protects the cell against environmental stressors. This defense is predominantly due to its asymmetry, with glycerophospholipids located in the inner leaflet and lipopolysaccharide (LPS) or lipooligosaccharide (LOS) confined to the outer leaflet. LPS consists of a lipid A anchor, a core oligosaccharide, and a distal O-antigen while LOS lacks O-antigen. While LPS/LOS is typically essential for growth, this is not the case for Acinetobacter baumannii. Despite this unique property, the synthesis of the core oligosaccharide of A. baumannii LOS is not well-described. Here, we characterized the LOS chemotypes of A. baumannii strains with mutations in a predicted core oligosaccharide locus via tandem mass spectrometry. This allowed for an extensive identification of genes required for core assembly that can be exploited to generate precise structural LOS modifications in many A. baumannii strains. We further investigated two chemotypically identical yet phenotypically distinct mutants, ∆2903 and ∆lpsB, that exposed a possible link between LOS and the peptidoglycan cell wall-two cell envelope components whose coordination has not yet been described in A. baumannii. Selective reconstruction of the core oligosaccharide via expression of 2903 and LpsB revealed that these proteins rely on each other for the unusual tandem transfer of two residues, KdoIII and N-acetylglucosaminuronic acid. The data presented not only allow for better usage of A. baumannii as a tool to study outer membrane integrity but also provide further evidence for a novel mechanism of core oligosaccharide assembly. IMPORTANCE Acinetobacter baumannii is a multidrug-resistant pathogen that produces lipooligosaccharide (LOS), a glycolipid that confers protective asymmetry to the bacterial outer membrane. The core oligosaccharide is a ubiquitous component of LOS that typically follows a well-established model of synthesis. In addition to providing an extensive analysis of the genes involved in the synthesis of the core region, we demonstrate that this organism has evidently diverged from the long-held archetype of core synthesis. Moreover, our data suggest that A. baumannii LOS assembly is important for cell division and likely intersects with the synthesis of the peptidoglycan cell wall, another essential component of the Gram-negative cell envelope. This connection between LOS and cell wall synthesis provides an intriguing foundation for a unique method of outer membrane biogenesis and cell envelope coordination.
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Affiliation(s)
- Leah M. VanOtterloo
- Department of Microbiology, College of Art and Sciences, University of Georgia, Athens, Georgia, USA
| | - Luis A. Macias
- Department of Chemistry, University of Texas at Austin, Austin, Texas, USA
| | - Matthew J. Powers
- Department of Microbiology, College of Art and Sciences, University of Georgia, Athens, Georgia, USA
| | | | - M. Stephen Trent
- Department of Microbiology, College of Art and Sciences, University of Georgia, Athens, Georgia, USA
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, Georgia, USA
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de Araújo HL, Picinato BA, Lorenzetti APR, Muthunayake NS, Rathnayaka-Mudiyanselage IW, dos Santos NM, Schrader J, Koide T, Marques MV. The DEAD-box RNA helicase RhlB is required for efficient RNA processing at low temperature in Caulobacter. Microbiol Spectr 2023; 11:e0193423. [PMID: 37850787 PMCID: PMC10715135 DOI: 10.1128/spectrum.01934-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Accepted: 09/12/2023] [Indexed: 10/19/2023] Open
Abstract
IMPORTANCE One of the most important control points in gene regulation is RNA stability, which determines the half-life of a transcript from its transcription until its degradation. Bacteria have evolved a sophisticated multi-enzymatic complex, the RNA degradosome, which is dedicated mostly to RNA turnover. The combined activity of RNase E and the other RNA degradosome enzymes provides an efficient pipeline for the complete degradation of RNAs. The DEAD-box RNA helicases are very often found in RNA degradosomes from phylogenetically distant bacteria, confirming their importance in unwinding structured RNA for subsequent degradation. This work showed that the absence of the RNA helicase RhlB in the free-living Alphaproteobacterium Caulobacter crescentus causes important changes in gene expression and cell physiology. These are probably due, at least in part, to inefficient RNA processing by the RNA degradosome, particularly at low-temperature conditions.
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Affiliation(s)
- Hugo L. de Araújo
- Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, Brazil
| | - Beatriz A. Picinato
- Departamento de Bioquímica e Imunologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, Brazil
| | - Alan P. R. Lorenzetti
- Departamento de Bioquímica e Imunologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, Brazil
| | | | | | - Naara M. dos Santos
- Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, Brazil
| | - Jared Schrader
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, USA
| | - Tie Koide
- Departamento de Bioquímica e Imunologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, Brazil
| | - Marilis V. Marques
- Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, Brazil
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Dhakephalkar T, Stukey G, Guan Z, Carman GM, Klein EA. Characterization of an evolutionarily distinct bacterial ceramide kinase from Caulobacter crescentus. J Biol Chem 2023:104894. [PMID: 37286040 PMCID: PMC10331486 DOI: 10.1016/j.jbc.2023.104894] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 05/27/2023] [Accepted: 06/01/2023] [Indexed: 06/09/2023] Open
Abstract
A common feature among nearly all Gram-negative bacteria is the requirement for lipopolysaccharide (LPS) in the outer leaflet of the outer membrane. LPS provides structural integrity to the bacterial membrane which aids bacteria in maintaining their shape and acts as a barrier from environmental stress and harmful substances such as detergents and antibiotics. Recent work has demonstrated that Caulobacter crescentus can survive without LPS due to the presence of the anionic sphingolipid ceramide-phosphoglycerate. Based on genetic evidence, we predicted that protein CpgB functions as a ceramide kinase and performs the first step in generating the phosphoglycerate head group. Here, we characterized the kinase activity of recombinantly expressed CpgB and demonstrated that it can phosphorylate ceramide to form ceramide 1-phosphate. The pH optimum for CpgB was 7.5, and the enzyme required Mg2+ as a cofactor. Mn2+, but not other divalent cations, could substitute for Mg2+. Under these conditions, the enzyme exhibited typical Michaelis-Menten kinetics with respect to NBD-C6-ceramide (Km,app=19.2 ± 5.5 μM; Vmax,app=2590 ± 230 pmol/min/mg enzyme) and ATP (Km,app=0.29 ± 0.07 mM; Vmax,app=10100 ± 996 pmol/min/mg enzyme). Phylogenetic analysis of CpgB revealed that CpgB belongs to a new class of ceramide kinases which is distinct from its eukaryotic counterpart; furthermore, the pharmacological inhibitor of human ceramide kinase (NVP-231) had no effect on CpgB. The characterization of a new bacterial ceramide kinase opens avenues for understanding the structure and function of the various microbial phosphorylated sphingolipids.
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Affiliation(s)
| | - Geordan Stukey
- Department of Food Science, Rutgers University, New Brunswick, NJ 08901, USA; Rutgers Center for Lipid Research, New Jersey Institute for Food Nutrition and Health, Rutgers University, New Brunswick, NJ 08901, USA
| | - Ziqiang Guan
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA
| | - George M Carman
- Department of Food Science, Rutgers University, New Brunswick, NJ 08901, USA; Rutgers Center for Lipid Research, New Jersey Institute for Food Nutrition and Health, Rutgers University, New Brunswick, NJ 08901, USA
| | - Eric A Klein
- Biology Department, Rutgers University-Camden, Camden, NJ 08102, USA; Department of Food Science, Rutgers University, New Brunswick, NJ 08901, USA; Rutgers Center for Lipid Research, New Jersey Institute for Food Nutrition and Health, Rutgers University, New Brunswick, NJ 08901, USA; Center for Computational and Integrative Biology, Rutgers University-Camden, Camden, NJ 08102, USA.
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Chen H, Zhu C, Zhou X. Effects of Lead and Cadmium Combined Heavy Metals on Liver Function and Lipid Metabolism in Mice. Biol Trace Elem Res 2023; 201:2864-2876. [PMID: 35994140 DOI: 10.1007/s12011-022-03390-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2022] [Accepted: 08/10/2022] [Indexed: 11/02/2022]
Abstract
Although a large number of studies have been conducted on lead (Pb) and cadmium (Cd) exposure individually, information regarding the toxicity of combined Pb and Cd exposure is relatively limited. The present study aims to investigate the toxicity of Pb-Cd combination exposure and the corresponding mechanism. A heavy metal exposure model was established in mice by subcutaneous intragastric administration of Pb-Cd (50:1) for 35 days. Body weight, diet, hair state, mental state, liver index, haematological index, biochemical indicators and pathological section analysis were used to comprehensively evaluate toxicity. Then, classical oxidative stress indexes and lipidomics techniques were used to explore the potential mechanism. The results showed that Pb-Cd caused the mice to have low appetite, poor spirit, significantly reduced activity, slow weight gain and irritated or drying hair. Pb-Cd also caused liver enlargement, significantly increased aspartate aminotransferase (AST) and alanine aminotransferase (ALT) enzyme activities, and resulted in pathological changes to the liver. Prolonged Pb-Cd exposure led to significantly increased thrombocyte haematocrit (PCT), white blood cell (WBC), platelet (PLT) and monocyte (MON) counts and decreased red blood cell (RBC), haemoglobin (HGB), haematocrit (HCT) and lymphocyte (LYM) counts. Pb-Cd increased oxidative stress by increasing the activity of superoxide dismutase (SOD) and lactate dehydrogenase (LDH) and the content of malondialdehyde (MDA). Finally, Pb-Cd triggered lipid metabolism disorders by regulating linoleic acid, sphingolipid and glycerolipid metabolism.
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Affiliation(s)
- Huaguo Chen
- Key Laboratory for Information System of Mountainous Areas and Protection of Ecological Environment, Guizhou Normal University, Guiyang, 550001, China.
- Guizhou Engineering Laboratory for Quality Control & Evaluation Technology of Medicine, Guizhou Normal University, Guiyang, 550001, China.
| | - Chengxiang Zhu
- Key Laboratory for Information System of Mountainous Areas and Protection of Ecological Environment, Guizhou Normal University, Guiyang, 550001, China
- Guizhou Engineering Laboratory for Quality Control & Evaluation Technology of Medicine, Guizhou Normal University, Guiyang, 550001, China
| | - Xin Zhou
- Key Laboratory for Information System of Mountainous Areas and Protection of Ecological Environment, Guizhou Normal University, Guiyang, 550001, China.
- Guizhou Engineering Laboratory for Quality Control & Evaluation Technology of Medicine, Guizhou Normal University, Guiyang, 550001, China.
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Dhakephalkar T, Stukey G, Guan Z, Carman GM, Klein EA. Characterization of an evolutionarily distinct bacterial ceramide kinase from Caulobacter crescentus. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.01.538943. [PMID: 37205603 PMCID: PMC10187206 DOI: 10.1101/2023.05.01.538943] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
A common feature among nearly all Gram-negative bacteria is the requirement for lipopolysaccharide (LPS) in the outer leaflet of the outer membrane. LPS provides structural integrity to the bacterial membrane which aids bacteria in maintaining their shape and acts as a barrier from environmental stress and harmful substances such as detergents and antibiotics. Recent work has demonstrated that Caulobacter crescentus can survive without LPS due to the presence of the anionic sphingolipid ceramide-phosphoglycerate. Based on genetic evidence, we predicted that protein CpgB functions as a ceramide kinase and performs the first step in generating the phosphoglycerate head group. Here, we characterized the kinase activity of recombinantly expressed CpgB and demonstrated that it can phosphorylate ceramide to form ceramide 1-phosphate. The pH optimum for CpgB was 7.5, and the enzyme required Mg 2+ as a cofactor. Mn 2+ , but not other divalent cations, could substitute for Mg 2+ . Under these conditions, the enzyme exhibited typical Michaelis-Menten kinetics with respect to NBD-C6-ceramide (K m,app =19.2 ± 5.5 μM; V max,app =2586.29 ± 231.99 pmol/min/mg enzyme) and ATP (K m,app =0.29 ± 0.07 mM; V max,app =10067.57 ± 996.85 pmol/min/mg enzyme). Phylogenetic analysis of CpgB revealed that CpgB belongs to a new class of ceramide kinases which is distinct from its eukaryotic counterpart; furthermore, the pharmacological inhibitor of human ceramide kinase (NVP-231) had no effect on CpgB. The characterization of a new bacterial ceramide kinase opens avenues for understanding the structure and function of the various microbial phosphorylated sphingolipids.
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