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Yu Y, Ma J, Guo Q, Ma J, Wang H. A novel 3-oxoacyl-ACP reductase (FabG3) is involved in the xanthomonadin biosynthesis of Xanthomonas campestris pv. campestris. MOLECULAR PLANT PATHOLOGY 2019; 20:1696-1709. [PMID: 31560825 PMCID: PMC6859482 DOI: 10.1111/mpp.12871] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Xanthomonas campestris pv. campestris (Xcc), the causal agent of black rot in crucifers, produces a membrane-bound yellow pigment called xanthomonadin to protect against photobiological and peroxidative damage, and uses a quorum-sensing mechanism mediated by the diffusible signal factor (DSF) family signals to regulate virulence factors production. The Xcc gene XCC4003, annotated as Xcc fabG3, is located in the pig cluster, which may be responsible for xanthomonadin synthesis. We report that fabG3 expression restored the growth of the Escherichia coli fabG temperature-sensitive mutant CL104 under non-permissive conditions. In vitro assays demonstrated that FabG3 catalyses the reduction of 3-oxoacyl-acyl carrier protein (ACP) intermediates in fatty acid synthetic reactions, although FabG3 had a lower activity than FabG1. Moreover, the fabG3 deletion did not affect growth or fatty acid composition. These results indicate that Xcc fabG3 encodes a 3-oxoacyl-ACP reductase, but is not essential for growth or fatty acid synthesis. However, the Xcc fabG3 knock-out mutant abolished xanthomonadin production, which could be only restored by wild-type fabG3, but not by other 3-oxoacyl-ACP reductase-encoding genes, indicating that Xcc FabG3 is specifically involved in xanthomonadin biosynthesis. Additionally, our study also shows that the Xcc fabG3-disrupted mutant affects Xcc virulence in host plants.
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Affiliation(s)
- Yonghong Yu
- Guangdong Food and Drug Vocational CollegeGuangzhouGuangdong510520China
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural OrganismsCollege of Life SciencesSouth China Agricultural UniversityGuangzhouGuangdong510642China
| | - Jianrong Ma
- Guangdong Food and Drug Vocational CollegeGuangzhouGuangdong510520China
| | - Qiaoqiao Guo
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural OrganismsCollege of Life SciencesSouth China Agricultural UniversityGuangzhouGuangdong510642China
| | - Jincheng Ma
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural OrganismsCollege of Life SciencesSouth China Agricultural UniversityGuangzhouGuangdong510642China
| | - Haihong Wang
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural OrganismsCollege of Life SciencesSouth China Agricultural UniversityGuangzhouGuangdong510642China
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Feng SX, Ma JC, Yang J, Hu Z, Zhu L, Bi HK, Sun YR, Wang HH. Ralstonia solanacearum fatty acid composition is determined by interaction of two 3-ketoacyl-acyl carrier protein reductases encoded on separate replicons. BMC Microbiol 2015; 15:223. [PMID: 26490537 PMCID: PMC4618531 DOI: 10.1186/s12866-015-0554-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2015] [Accepted: 10/08/2015] [Indexed: 12/21/2022] Open
Abstract
Background FabG is the only known enzyme that catalyzes reduction of the 3-ketoacyl-ACP intermediates of bacterial fatty acid synthetic pathways. However, there are two Ralstonia solanacearum genes, RSc1052 (fabG1) and RSp0359 (fabG2), annotated as encoding putative 3-ketoacyl-ACP reductases. Both FabG homologues possess the conserved catalytic triad and the N-terminal cofactor binding sequence of the short chain dehydrogenase/reductase (SDR) family. Thus, it seems reasonable to hypothesize that RsfabG1 and RsfabG2 both encode functional 3-ketoacyl-ACP reductases and play important roles in R. solanacearum fatty acid synthesis and growth. Methods Complementation of Escherichia colifabG temperature-sensitive mutant with R. solanacearum fabGs encoded plasmids was carried out to test the function of RsfabGs in fatty acid biosynthesis. RsFabGs proteins were purified by nickel chelate chromatography and fatty acid biosynthetic reaction was reconstituted to investigate the 3-ketoacyl-ACP reductase activity of RsFabGs in vitro. Disruption of both RsfabG genes was done via DNA homologous recombination to test the function of both RsfabG in vivo. And more we also carried out pathogenicity tests on tomato plants using RsfabG mutant strains. Results We report that expression of either of the two proteins (RsFabG1 and RsFabG2) restores growth of the E. coli fabG temperature-sensitive mutant CL104 under non-permissive conditions. In vitro assays demonstrate that both proteins restore fatty acid synthetic ability to extracts of the E. coli strain. The RsfabG1 gene carried on the R. solanacearum chromosome is essential for growth of the bacterium, as is the case for fabG in E. coli. In contrast, the null mutant strain with the megaplasmid-encoded RsfabG2 gene is viable but has a fatty acid composition that differs significantly from that of the wild type strain. Our study also shows that RsFabG2 plays a role in adaptation to high salt concentration and low pH, and in pathogenesis of disease in tomato plants. Conclusion R. solanacearum encodes two 3-ketoacyl-ACP reductases that both have functions in fatty acid synthesis. We supply the first evidence that, like other enzymes in the bacterial fatty acid biosynthetic pathway, one bacterium may simultaneously possess two or more 3-oxoacyl-ACP reductase isozymes. Electronic supplementary material The online version of this article (doi:10.1186/s12866-015-0554-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Sai-Xiang Feng
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University, No.483 Wushan Road, Tianhe, Guangzhou, 510642, P. R. China.
| | - Jin-Cheng Ma
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University, No.483 Wushan Road, Tianhe, Guangzhou, 510642, P. R. China.
| | - Ji Yang
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University, No.483 Wushan Road, Tianhe, Guangzhou, 510642, P. R. China.
| | - Zhe Hu
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University, No.483 Wushan Road, Tianhe, Guangzhou, 510642, P. R. China.
| | - Lei Zhu
- Departments of Microbiology and Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.
| | - Hong-Kai Bi
- Department of Pathogenic Biology, Jiangsu Key Laboratory of Pathogenic Biology, Nanjing Medical University, Nanjing, Jiangsu, 210029, China.
| | - Yi-Rong Sun
- Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, Guangdong, 510530, China.
| | - Hai-Hong Wang
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University, No.483 Wushan Road, Tianhe, Guangzhou, 510642, P. R. China.
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Qiu X, Janson CA, Court RI, Smyth MG, Payne DJ, Abdel-Meguid SS. Molecular basis for triclosan activity involves a flipping loop in the active site. Protein Sci 1999; 8:2529-32. [PMID: 10595560 PMCID: PMC2144207 DOI: 10.1110/ps.8.11.2529] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
The crystal structure of the Escherichia coli enoyl reductase-NAD+-triclosan complex has been determined at 2.5 A resolution. The Ile192-Ser198 loop is either disordered or in an open conformation in the previously reported structures of the enzyme. This loop adopts a closed conformation in our structure, forming van der Waals interactions with the inhibitor and hydrogen bonds with the bound NAD+ cofactor. The opening and closing of this flipping loop is likely an important factor in substrate or ligand recognition. The closed conformation of the loop appears to be a critical feature for the enhanced binding potency of triclosan, and a key component in future structure-based inhibitor design.
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Affiliation(s)
- X Qiu
- Department of Structural Biology, SmithKline Beecham Pharmaceuticals, King of Prussia, Pennsylvania 19406, USA.
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