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Cronan JE. Unsaturated fatty acid synthesis in bacteria: Mechanisms and regulation of canonical and remarkably noncanonical pathways. Biochimie 2024; 218:137-151. [PMID: 37683993 PMCID: PMC10915108 DOI: 10.1016/j.biochi.2023.09.007] [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: 06/19/2023] [Revised: 08/02/2023] [Accepted: 09/04/2023] [Indexed: 09/10/2023]
Abstract
Unsaturated phospholipid acyl chains are required for membrane function in most bacteria. The double bonds of the cis monoenoic chains arise by two distinct pathways depending on whether oxygen is required. The oxygen-independent pathway (traditionally called the anaerobic pathway) introduces the cis double bond by isomerization of the trans double bond intermediate of the fatty acid elongation cycle. Double bond isomerization occurs at an intermediate chain length (e.g., C10) and the isomerization product is elongated to the C16-C18 chains that become phospholipid monoenoic acyl chains. This pathway was first delineated in Escherichia coli and became the paradigm pathway. However, studies of other bacteria show deviations from this paradigm, the most exceptional being reversal of the fatty acid elongation cycle by a reaction paralleling the initial step in the β-oxidative degradation of fatty acids. In the oxygen-dependent pathway diiron enzymes called desaturases introduce a double bond into a saturated acyl chain by regioselective cis dehydrogenation through activation of molecular oxygen with an active-site diiron cluster. This difficult hydrogen abstraction from a methylene group often occurs at the midpoint of a saturated fatty acyl chain. In bacteria the acyl chain is a phospholipid acyl chain, and the desaturase is membrane bound. Both the oxygen-independent oxygen-dependent pathways are transcriptionally regulated by repressor and activator proteins that respond to small molecule ligands such as acyl-CoAs. However, in Bacillus subtilis the desaturase is synthesized only at low growth temperatures, a process controlled by a signal transduction regulatory pathway dependent on membrane lipid properties.
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Affiliation(s)
- John E Cronan
- Departments of Microbiology and Biochemistry, University of Illinois, Urbana, 61801, USA.
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2
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Cerone M, Smith TK. Desaturases: Structural and mechanistic insights into the biosynthesis of unsaturated fatty acids. IUBMB Life 2022; 74:1036-1051. [PMID: 36017969 PMCID: PMC9825965 DOI: 10.1002/iub.2671] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Accepted: 08/21/2022] [Indexed: 01/11/2023]
Abstract
This review highlights the key role of fatty acid desaturases in the synthesis of naturally occurring, more common and not unsaturated fatty acids. The three major classes of fatty acid desaturases, such as acyl-lipid, acyl-acyl carrier protein and acyl-coenzyme A, are described in detail, with particular attention to the cellular localisation, the structure, the substrate and product specificity and the expression and regulation of desaturase genes. The review also gives an insight into the biocatalytic reaction of fatty acid desaturation by covering the general and more class-specific mechanistic studies around the synthesis of unsaturated fatty acids Finally, we conclude the review by looking at the numerous novel applications for desaturases in order to meet the very high demand for polyunsaturated fatty acids, taking into account the opportunity for the development of new, more efficient, easily reproducible, sustainable bioengineering advances in the field.
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Affiliation(s)
- Michela Cerone
- Biomedical Sciences Research ComplexUniversity of St AndrewsSt AndrewsScotland
| | - Terry K. Smith
- Biomedical Sciences Research ComplexUniversity of St AndrewsSt AndrewsScotland
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3
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Wu J, Wu C, Rong C, Tian J, Jiang N, Wu R, Yue X, Shi H. Catalytic mechanisms underlying fungal fatty acid desaturases activities. Crit Rev Biotechnol 2022:1-17. [PMID: 35658758 DOI: 10.1080/07388551.2022.2063106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Polyunsaturated fatty acids (PUFAs) have beneficial roles in a variety of human pathologies and disorders. Owing to the limited source of PUFAs in animals and plants, microorganisms, especially fungi, have become a new source of PUFAs. In fungi, fatty acid desaturases (F-FADS) are the main enzymes that convert saturated fatty acids (SFAs) into PUFAs. Their catalytic activities and substrate specificities, which are directly dependent on the structure of the FADS proteins, determine their efficiency to convert SFAs to PUFAs. Catalytic mechanisms underlying F-FADS activities can be determined from the findings of the relationship between their structure and function. In this review, the advances made in the past decade in terms of catalytic activities and substrate specificities of the fungal FADS cluster are summarized. The relationship between the key domain(s) and site(s) in F-FADS proteins and their catalytic activity is highlighted, and the FADS cluster is analyzed phylogenetically. In addition, subcellular localization of F-FADS is discussed. Finally, we provide prospective crystal structures of F-FADSs. The findings may provide a reference for the resolution of the crystal structures of F-FADS proteins and facilitate the increase in fungal PUFA production for human health.
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Affiliation(s)
- Junrui Wu
- College of Food Science, Shenyang Agricultural University, Shenyang, China.,Liaoning Engineering Research Center of Food Fermentation Technology, Shenyang Agricultural University, Shenyang, China.,Shenyang Key Laboratory of Microbial Fermentation Technology Innovation, Shenyang Agricultural University, Shenyang, China
| | - Chen Wu
- College of Food Science, Shenyang Agricultural University, Shenyang, China
| | - Chunchi Rong
- School of Food Science and Pharmaceutical Engineering, Nanjing Normal University, Nanjing, China
| | - Jinlong Tian
- College of Food Science, Shenyang Agricultural University, Shenyang, China
| | - Nan Jiang
- College of Food Science, Shenyang Agricultural University, Shenyang, China
| | - Rina Wu
- College of Food Science, Shenyang Agricultural University, Shenyang, China.,Liaoning Engineering Research Center of Food Fermentation Technology, Shenyang Agricultural University, Shenyang, China.,Shenyang Key Laboratory of Microbial Fermentation Technology Innovation, Shenyang Agricultural University, Shenyang, China
| | - Xiqing Yue
- College of Food Science, Shenyang Agricultural University, Shenyang, China.,Liaoning Engineering Research Center of Food Fermentation Technology, Shenyang Agricultural University, Shenyang, China.,Shenyang Key Laboratory of Microbial Fermentation Technology Innovation, Shenyang Agricultural University, Shenyang, China
| | - Haisu Shi
- College of Food Science, Shenyang Agricultural University, Shenyang, China.,Liaoning Engineering Research Center of Food Fermentation Technology, Shenyang Agricultural University, Shenyang, China.,Shenyang Key Laboratory of Microbial Fermentation Technology Innovation, Shenyang Agricultural University, Shenyang, China
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4
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Starikov AY, Sidorov RA, Mironov KS, Goriainov SV, Los DA. Delta or Omega? Δ12 (ω6) fatty acid desaturases count 3C after the pre-existing double bond. Biochimie 2020; 179:46-53. [PMID: 32946991 DOI: 10.1016/j.biochi.2020.09.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Revised: 08/25/2020] [Accepted: 09/14/2020] [Indexed: 11/24/2022]
Abstract
Fatty acid desaturases (FADs) represent a class of oxygen-dependent enzymes that dehydrogenate C-C bonds in the fatty acids (FAs) producing unsaturated CC double bonds that markedly change the properties of biological membranes. FADs are highly specific towards their acyl substrates, the position and configuration of the introduced double bonds. The double bond positioning of soluble acyl-carrier-protein Δ9-FADs was determined relative to the carboxyl end of a FA. Similar mode was suggested for the acyl-lipid Δ12-FADs (also known as ω6-FADs), however, their exact counting order remain unknown. Here we used monounsaturated odd- (17:1Δ10) and even-chain (18:1Δ11) FAs to show that acyl-lipid Δ12-FADs of, at least, two cyanobacterial species, Gloeobacter violaceus and Synechocystis sp. strain PCC 6803, use neither end of the fatty acid (Δ or ω) as a counting reference point; but count three carbons toward the methyl end from an existing double bond in the monoene precursors irrespective of a FA chain length.
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Affiliation(s)
- Alexander Y Starikov
- K.A. Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Botanicheskaya Street 35, Moscow, 127276, Russian Federation
| | - Roman A Sidorov
- K.A. Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Botanicheskaya Street 35, Moscow, 127276, Russian Federation
| | - Kirill S Mironov
- K.A. Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Botanicheskaya Street 35, Moscow, 127276, Russian Federation
| | - Sergei V Goriainov
- Peoples' Friendship University of Russia (RUDN University), Miklukho-Maklaya Street, Build. 6, Moscow, 117198, Russian Federation
| | - Dmitry A Los
- K.A. Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Botanicheskaya Street 35, Moscow, 127276, Russian Federation.
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Molecular mechanisms for biosynthesis and assembly of nutritionally important very long chain polyunsaturated fatty acids in microorganisms. Prog Lipid Res 2020; 79:101047. [DOI: 10.1016/j.plipres.2020.101047] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 05/29/2020] [Accepted: 06/09/2020] [Indexed: 12/23/2022]
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Tseytin I, Mitrovic B, David N, Langenfeld K, Zarivach R, Diepold A, Sal-Man N. The Role of the Small Export Apparatus Protein, SctS, in the Activity of the Type III Secretion System. Front Microbiol 2019; 10:2551. [PMID: 31798543 PMCID: PMC6863770 DOI: 10.3389/fmicb.2019.02551] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2019] [Accepted: 10/22/2019] [Indexed: 12/15/2022] Open
Abstract
Many gram-negative pathogens utilize a protein complex, termed the type III secretion system (T3SS), to inject virulence factors from their cytoplasm directly into the host cell. An export apparatus that is formed by five putative integral membrane proteins (SctR/S/T/U/V), resides at the center of the T3SS complex. In this study, we characterized the smallest export apparatus protein, SctS, which contains two putative transmembrane domains (PTMD) that dynamically extract from the inner membrane and adopt a helix-turn-helix structure upon assembly of the T3SS. Replacement of each SctS PTMD with an alternative hydrophobic sequence resulted in abolishment of the T3SS activity, yet SctS self- and hetero-interactions as well as the overall assembly of the T3SS complex were unaffected. Our findings suggest that SctS PTMDs are not crucial for the interactions or the assembly of the T3SS base complex but rather that they are involved in adjusting the orientation of the export apparatus relative to additional T3SS sub-structures, such as the cytoplasmic- and the inner-membrane rings. This ensures the fittings between the dynamic and static components of the T3SS and supports the functionality of the T3SS complex.
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Affiliation(s)
- Irit Tseytin
- The Shraga Segal Department of Microbiology, Immunology and Genetics, Faculty of Health Sciences, Ben-Gurion University of the Negev, Be'er Sheva, Israel
| | - Bosko Mitrovic
- The Shraga Segal Department of Microbiology, Immunology and Genetics, Faculty of Health Sciences, Ben-Gurion University of the Negev, Be'er Sheva, Israel
| | - Nofar David
- The Shraga Segal Department of Microbiology, Immunology and Genetics, Faculty of Health Sciences, Ben-Gurion University of the Negev, Be'er Sheva, Israel
| | - Katja Langenfeld
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Raz Zarivach
- Department of Life Sciences and the National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Be'er Sheva, Israel
| | - Andreas Diepold
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Neta Sal-Man
- The Shraga Segal Department of Microbiology, Immunology and Genetics, Faculty of Health Sciences, Ben-Gurion University of the Negev, Be'er Sheva, Israel
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