1
|
Yin Y, Li R, Liang WT, Zhang WB, Hu Z, Ma JC, Wang HH. Of its five acyl carrier proteins, only AcpP1 functions in Ralstonia solanacearum fatty acid synthesis. Front Microbiol 2022; 13:1014971. [PMID: 36212838 PMCID: PMC9542644 DOI: 10.3389/fmicb.2022.1014971] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Accepted: 09/06/2022] [Indexed: 11/13/2022] Open
Abstract
The fatty acid synthesis (FAS) pathway is essential for bacterial survival. Acyl carrier proteins (ACPs), donors of acyl moieties, play a central role in FAS and are considered potential targets for the development of antibacterial agents. Ralstonia solanacearum, a primary phytopathogenic bacterium, causes bacterial wilt in more than 200 plant species. The genome of R. solanacearum contains five annotated acp genes, acpP1, acpP2, acpP3, acpP4, and acpP5. In this study, we characterized the five putative ACPs and confirmed that only AcpP1 is involved in FAS and is necessary for the growth of R. solanacearum. We also found that AcpP2 and AcpP4 participate in the polyketide synthesis pathway. Unexpectedly, the disruption of four acp genes (acpP2, acpP3, acpP4, and acpP5) allowed the mutant strain to grow as well as the wild-type strain, but attenuated the bacterium’s pathogenicity in the host plant tomato, suggesting that these four ACPs contribute to the virulence of R. solanacearum through mechanisms other than the FAS pathway.
Collapse
|
2
|
Padilla-Gómez J, Olea-Ozuna RJ, Contreras-Martínez S, Morales-Tarré O, García-Soriano DA, Sahonero-Canavesi DX, Poggio S, Encarnación-Guevara S, López-Lara IM, Geiger O. Specialized acyl carrier protein used by serine palmitoyltransferase to synthesize sphingolipids in Rhodobacteria. Front Microbiol 2022; 13:961041. [PMID: 35992722 PMCID: PMC9386255 DOI: 10.3389/fmicb.2022.961041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Accepted: 07/11/2022] [Indexed: 11/13/2022] Open
Abstract
Serine palmitoyltransferase (SPT) catalyzes the first and committed step in sphingolipid biosynthesis condensating L-serine and acyl-CoA to form 3-oxo-sphinganine. Whenever the structural gene for SPT is present in genomes of Rhodobacteria (α-, β-, and γ-Proteobacteria), it co-occurs with genes coding for a putative acyl carrier protein (ACP) and a putative acyl-CoA synthetase (ACS). In the α-proteobacterium Caulobacter crescentus, CC_1162 encodes an SPT, whereas CC_1163 and CC_1165 encode the putative ACP and ACS, respectively, and all three genes are known to be required for the formation of the sphingolipid intermediate 3-oxo-sphinganine. Here we show that the putative ACP possesses a 4'-phosphopantetheine prosthetic group, is selectively acylated by the putative ACS and therefore is a specialized ACP (AcpR) required for sphingolipid biosynthesis in Rhodobacteria. The putative ACS is unable to acylate coenzyme A or housekeeping ACPs, but acylates specifically AcpR. Therefore, it is a specialized acyl-ACP synthetase (AasR). SPTs from C. crescentus, Escherichia coli B, or Sphingomonas wittichii use preferentially acyl-AcpR as thioester substrate for 3-oxo-sphinganine synthesis. Whereas acyl-AcpR from C. crescentus is a good substrate for SPTs from distinct Rhodobacteria, acylation of a specific AcpR is achieved by the cognate AasR from the same bacterium. Rhodobacteria might use this more complex way of 3-oxo-sphinganine formation in order to direct free fatty acids toward sphingolipid biosynthesis.
Collapse
Affiliation(s)
- Jonathan Padilla-Gómez
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | | | | | - Orlando Morales-Tarré
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | | | | | - Sebastian Poggio
- Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad de México, Mexico
| | | | - Isabel M. López-Lara
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Otto Geiger
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
- *Correspondence: Otto Geiger,
| |
Collapse
|
3
|
Ma JC, Wu YQ, Cao D, Zhang WB, Wang HH. Only Acyl Carrier Protein 1 (AcpP1) Functions in Pseudomonas aeruginosa Fatty Acid Synthesis. Front Microbiol 2017; 8:2186. [PMID: 29176964 PMCID: PMC5686131 DOI: 10.3389/fmicb.2017.02186] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Accepted: 10/25/2017] [Indexed: 11/21/2022] Open
Abstract
The genome of Pseudomonas aeruginosa contains three open reading frames, PA2966, PA1869, and PA3334, which encode putative acyl carrier proteins, AcpP1, AcpP2, and AcpP3, respectively. In this study, we found that, although these apo-ACPs were successfully phosphopantetheinylated by P. aeruginosa phosphopantetheinyl transferase (PcpS) and all holo-forms of these proteins could be acylated by Vibrio harveyi acyl-ACP synthetase (AasS), only AcpP1 could be used as a substrate for the synthesis of fatty acids, catalyzed by P. aeruginosa cell free extracts in vitro, and only acpP1 gene could restore growth in the Escherichia coliacpP mutant strain CY1877. And P. aeruginosaacpP1 could not be deleted, while disruption of acpP2 or acpP3 in the P. aeruginosa genome allowed mutant strains to grow as well as the wild type strain. These findings confirmed that only P. aeruginosa AcpP1 functions in fatty acid biosynthesis, and that acpP2 and acpP3 do not play roles in the fatty acid synthetic pathway. Moreover, disruption of acpP2 and acpP3 did not affect the ability of P. aeruginosa to produce N-acylhomoserine lactones (AHL), but replacement of P. aeruginosaacpP1 with E. coliacpP caused P. aeruginosa to reduce the production of AHL molecules, which indicated that neither P. aeruginosa AcpP2 nor AcpP3 can act as a substrate for synthesis of AHL molecules in vivo. Furthermore, replacement of acpP1 with E. coliacpP reduced the ability of P. aeruginosa to produce some exo-products and abolished swarming motility in P. aeruginosa.
Collapse
Affiliation(s)
- Jin-Cheng Ma
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University, Guangzhou, China
| | - Yun-Qi Wu
- Department of Chemistry and Biomolecular Sciences, Macquarie University, North Ryde, NSW, Australia
| | - Dan Cao
- Forensic Science Center of Qingyuan, Qingyuan Public Security Department, Qingyuan, China
| | - Wen-Bin Zhang
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University, Guangzhou, China
| | - Hai-Hong Wang
- Guangdong Provincial Key Laboratory of Protein Function and Regulation in Agricultural Organisms, College of Life Sciences, South China Agricultural University, Guangzhou, China
| |
Collapse
|
4
|
Paulucci NS, Dardanelli MS, García de Lema M. Biochemical and molecular evidence of a Δ9 fatty acid desaturase from Ensifer meliloti 1021. Microbiol Res 2014; 169:463-8. [DOI: 10.1016/j.micres.2013.08.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2013] [Revised: 07/23/2013] [Accepted: 08/10/2013] [Indexed: 11/16/2022]
|
5
|
Dávila-Martínez Y, Ramos-Vega AL, Contreras-Martínez S, Encarnación S, Geiger O, López-Lara IM. SMc01553 is the sixth acyl carrier protein in Sinorhizobium meliloti 1021. Microbiology (Reading) 2010; 156:230-239. [DOI: 10.1099/mic.0.033480-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Acyl carrier proteins (ACPs) are required for the transfer of acyl intermediates during fatty acid and polyketide syntheses. In Sinorhizobium meliloti 1021 there are five known ACPs: AcpP, NodF, AcpXL, the ACP domain in RkpA and SMb20651. The genome sequence of S. meliloti 1021 also reveals the ORF SMc01553, annotated as a putative ACP. smc01553 is part of a 6.6 kb DNA region that is duplicated in the chromosome and in the pSymb plasmid, the result of a recent duplication event. SMc01553 overexpressed in Escherichia coli was labelled in vivo with [3H]β-alanine, a biosynthetic building block of the 4′-phosphopantetheine prosthetic group of ACPs. The purified SMc01553 was modified with 4′-phosphopantetheine in the presence of S. meliloti holo-ACP synthase, and this modification resulted in a major conformational change of the protein structure, since the holo-form runs faster in native PAGE than the apo-form. SMc01553 could not be loaded with a malonyl group by malonyl-CoA-ACP transacylase from S. meliloti. Using RT-PCR we could show the presence of mRNA for SMc01553 and of the duplicated ORF SMb22007 in cultures of S. meliloti. However, a mutant in which the two duplicated regions were deleted did not show any different phenotype with respect to the wild-type in the free-living or symbiotic lifestyle.
Collapse
Affiliation(s)
- Yadira Dávila-Martínez
- Programa de Ecología Genómica, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Apdo. Postal 565-A, Cuernavaca, Morelos, C.P. 62251, Mexico
| | - Ana Laura Ramos-Vega
- Programa de Ecología Genómica, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Apdo. Postal 565-A, Cuernavaca, Morelos, C.P. 62251, Mexico
| | - Sandra Contreras-Martínez
- Programa de Genómica Funcional de Procariontes, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Apdo. Postal 565-A, Cuernavaca, Morelos, C.P. 62251, Mexico
| | - Sergio Encarnación
- Programa de Genómica Funcional de Procariontes, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Apdo. Postal 565-A, Cuernavaca, Morelos, C.P. 62251, Mexico
| | - Otto Geiger
- Programa de Ecología Genómica, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Apdo. Postal 565-A, Cuernavaca, Morelos, C.P. 62251, Mexico
| | - Isabel M. López-Lara
- Programa de Ecología Genómica, Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Apdo. Postal 565-A, Cuernavaca, Morelos, C.P. 62251, Mexico
| |
Collapse
|
6
|
Functional nodFE genes are present in Sinorhizobium sp. strain MUS10, a symbiont of the tropical legume Sesbania rostrata. Appl Environ Microbiol 2008; 74:2921-3. [PMID: 18326678 DOI: 10.1128/aem.00075-08] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We have cloned the nodFE operon from Sinorhizobium sp. strain MUS10. MUS10 NodF shows sequence homology to acyl carrier protein and enables an S. meliloti nodF mutant to effectively nodulate alfalfa. Our results demonstrate the occurrence of nodFE in a symbiont that nodulates a legume host not belonging to the galegoid group.
Collapse
|
7
|
Ferguson GP, Datta A, Carlson RW, Walker GC. Importance of unusually modified lipid A in Sinorhizobium stress resistance and legume symbiosis. Mol Microbiol 2005; 56:68-80. [PMID: 15773979 DOI: 10.1111/j.1365-2958.2005.04536.x] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Sinorhizobium meliloti, a legume symbiont and Brucella abortus, a phylogenetically related mammalian pathogen, both require their BacA proteins to establish chronic intracellular infections in their respective hosts. The lipid A molecules of S. meliloti and B. abortus are unusually modified with a very-long-chain fatty acid (VLCFA; C > or = 28) and we discovered that BacA is involved in this unusual modification. This observation raised the possibility that the unusual lipid A modification could be crucial for the chronic infection of both S. meliloti and B. abortus. We investigated this by constructing and characterizing S. meliloti mutants in the lpxXL and acpXL genes, which encode an acyl transferase and acyl carrier protein directly involved in the biosynthesis of VLCFA-modified lipid A. Our analysis revealed that the unusually modified lipid A is important, but not crucial, for S. meliloti chronic infection and that BacA must have an additional function, which in combination with its observed effect on the lipid A in the free-living form of S. meliloti, is essential for the chronic infection. Additionally, we discovered that in the absence of VLCFAs, S. meliloti produces novel pentaacylated lipid A species, modified with unhydroxylated fatty acids, which are important for stress resistance.
Collapse
Affiliation(s)
- Gail P Ferguson
- Institute of Structural and Molecular Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, EH9 3JR, UK.
| | | | | | | |
Collapse
|
8
|
Ferguson GP, Datta A, Baumgartner J, Roop RM, Carlson RW, Walker GC. Similarity to peroxisomal-membrane protein family reveals that Sinorhizobium and Brucella BacA affect lipid-A fatty acids. Proc Natl Acad Sci U S A 2004; 101:5012-7. [PMID: 15044696 PMCID: PMC387365 DOI: 10.1073/pnas.0307137101] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Sinorhizobium meliloti, a legume symbiont, and Brucella abortus, a phylogenetically related mammalian pathogen, both require the bacterial-encoded BacA protein to establish chronic intracellular infections in their respective hosts. We found that the bacterial BacA proteins share sequence similarity with a family of eukaryotic peroxisomal-membrane proteins, including the human adrenoleukodystrophy protein, required for the efficient transport of very-long-chain fatty acids out of the cytoplasm. This insight, along with the increased sensitivity of BacA-deficient mutants to detergents and cell envelope-disrupting agents, led us to discover that BacA affects the very-long-chain fatty acid (27-OHC28:0 and 29-OHC30:0) content of both Sinorhizobium and Brucella lipid A. We discuss models for how BacA function affects the lipid-A fatty-acid content and why this activity could be important for the establishment of chronic intracellular infections.
Collapse
Affiliation(s)
- Gail P Ferguson
- Biology Department, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
| | | | | | | | | | | |
Collapse
|
9
|
Marketon MM, Gronquist MR, Eberhard A, González JE. Characterization of the Sinorhizobium meliloti sinR/sinI locus and the production of novel N-acyl homoserine lactones. J Bacteriol 2002; 184:5686-95. [PMID: 12270827 PMCID: PMC139616 DOI: 10.1128/jb.184.20.5686-5695.2002] [Citation(s) in RCA: 175] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Sinorhizobium meliloti is a soil bacterium which can establish a nitrogen-fixing symbiosis with the legume Medicago sativa. Recent work has identified a pair of genes, sinR and sinI, which represent a potential quorum-sensing system and are responsible for the production of N-acyl homoserine lactones (AHLs) in two S. meliloti strains, Rm1021 and Rm41. In this work, we characterize the sinRI locus and show that these genes are responsible for the synthesis of several long-chain AHLs ranging from 12 to 18 carbons in length. Four of these, 3-oxotetradecanoyl HL, 3-oxohexadecenoyl HL, hexadecenoyl HL, and octadecanoyl HL, have novel structures. This is the first report of AHLs having acyl chains longer than 14 carbons. We show that a disruption in sinI eliminates these AHLs and that a sinR disruption results in only basal levels of the AHLs. Moreover, the same sinI and sinR mutations also lead to a decrease in the number of pink nodules during nodulation assays, as well as a slight delay in the appearance of pink nodules, indicating a role for quorum sensing in symbiosis. We also show that sinI and sinR mutants are still capable of producing several short-chain AHLs, one of which was identified as octanoyl HL. We believe that these short-chain AHLs are evidence of a second quorum-sensing system in Rm1021, which we refer to here as the mel system, for "S. meliloti."
Collapse
Affiliation(s)
- Melanie M Marketon
- Department of Molecular and Cell Biology, University of Texas at Dallas, Richardson, Texas 75083-0688, USA
| | | | | | | |
Collapse
|
10
|
Weissenmayer B, Gao JL, López-Lara IM, Geiger O. Identification of a gene required for the biosynthesis of ornithine-derived lipids. Mol Microbiol 2002; 45:721-33. [PMID: 12139618 DOI: 10.1046/j.1365-2958.2002.03043.x] [Citation(s) in RCA: 69] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Phospholipids are the membrane-forming constituents in all living organisms. In addition to phosphorus-containing lipids, the membranes of numerous bacteria contain significant amounts of phosphorus-free polar lipids, often derived from amino acids. Although lipids derived from the amino acid ornithine are widespread among bacteria, their biosynthesis is unknown. Here, we describe the isolation of mutants of Sinorhizobium meliloti deficient in the biosynthesis of ornithine-derived lipids (OL). Complementation of such mutants with a sinorhi-zobial cosmid gene bank, subcloning of the complementing fragment and sequencing of the subclone led to the identification of a gene (olsA) coding for a presumptive acyltransferase. Amplification of this gene and its expression in OL-deficient mutant backgrounds of S. meliloti demonstrates that it is required for OL biosynthesis. An OL-deficient mutant of S. meliloti disrupted in olsA shows wild type-like growth behaviour and is capable of inducing nitrogen-fixing nodules on legume hosts. A lyso-ornithine lipid-dependent acyltransferase activity forming OL requires acyl-AcpP as the acyl donor and expression of the olsA gene.
Collapse
Affiliation(s)
- Barbara Weissenmayer
- Centro de Investigación sobre Fijación de Nitrógeno, Universidad Nacional Autónoma de México, Cuernavaca, Morelos
| | | | | | | |
Collapse
|
11
|
Geiger O, López-Lara IM. Rhizobial acyl carrier proteins and their roles in the formation of bacterial cell-surface components that are required for the development of nitrogen-fixing root nodules on legume hosts. FEMS Microbiol Lett 2002; 208:153-62. [PMID: 11959430 DOI: 10.1111/j.1574-6968.2002.tb11075.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Acyl carrier protein (ACP) of Escherichia coli is a small acidic protein which functions as carrier of growing acyl chains during their biosynthesis and as donor of acyl chains during transfer to target molecules. This unique ACP of E. coli is expressed constitutively. In more complex bacteria, multiple ACPs are present, indicating a channeling of pools of multi-carbon units into different biosynthetic routes. In rhizobia, for example, besides the constitutive ACP (AcpP) involved in the biosynthesis and transfer of common fatty acids, three specialized ACPs have been reported: (1) the flavonoid-inducible nodulation protein NodF, (2) AcpXL that transfers 27-hydroxyoctacosanoic acid to a sugar backbone during lipid A biosynthesis, and (3) the RkpF protein which is required for the biosynthesis of rhizobial capsular polysaccharides. All three of those specialized rhizobial ACPs are required for the biosynthesis of cell-surface molecules that play a role in establishing the symbiotic relationship between rhizobia and their legume hosts. Surprisingly, the recently sequenced genomes from Mesorhizobium loti and Sinorhizobium meliloti suggest even more candidates for ACPs in rhizobia.
Collapse
Affiliation(s)
- Otto Geiger
- Centro de Investigación sobre Fijación de Nitrógeno, Universidad Nacional Autónoma de México, Apdo. Postal 565-A, Cuernavaca, Morelos CP62210, Mexico.
| | | |
Collapse
|
12
|
Schaeffer ML, Agnihotri G, Kallender H, Brennan PJ, Lonsdale JT. Expression, purification, and characterization of the Mycobacterium tuberculosis acyl carrier protein, AcpM. BIOCHIMICA ET BIOPHYSICA ACTA 2001; 1532:67-78. [PMID: 11420175 DOI: 10.1016/s1388-1981(01)00116-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Mycolic acids are generated in Mycobacterium tuberculosis as a result of the interaction of two fatty acid biosynthetic systems: the multifunctional polypeptide, FASI, in which the acyl carrier protein (ACP) domain forms an integral part of the polypeptide, and the dissociated FASII system, which is composed of monofunctional enzymes and a discrete ACP (AcpM). In order to characterize enzymes of the FASII system, large amounts of AcpM are required to generate substrates such as holo-AcpM, malonyl-AcpM and acyl-AcpM. The M. tuberculosis acpM gene was overexpressed in Escherichia coli and AcpM purified, yielding approximately 15-20 mg/l of culture. Analysis of AcpM by mass spectrometry, N-terminal sequencing, amino acid analysis, and gas chromatography indicated the presence of three species, apo-, holo-, and acyl-AcpM, the former comprising up to 65% of the total pool. The apo-AcpM was purified away from the in vivo generated holo- and acyl-forms, which were inseparable and heterogeneous with respect to acyl chain lengths. Once purified, we were able to convert apo-AcpM into holo- and acyl-forms. These procedures provide the means for the preparation of the large quantities of AcpM and derivatives needed for characterization of the purified enzymes of the mycobacterial FASII system.
Collapse
|
13
|
López-Lara IM, Geiger O. The nodulation protein NodG shows the enzymatic activity of an 3-oxoacyl-acyl carrier protein reductase. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2001; 14:349-357. [PMID: 11277432 DOI: 10.1094/mpmi.2001.14.3.349] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The acyl carrier protein NodF is required for the synthesis of unusual polyunsaturated fatty acids that confer specificity to lipochitin oligosaccharide nodulation (Nod) factors of Rhizobium leguminosarum. In this study, homogeneous NodF protein was used as a ligand to identify proteins of R. leguminosarum that specifically interact with NodF and presumably are involved in the biosynthesis or transfer of the unusual fatty acids. The N-terminal amino acid sequence of a 29-kDa protein that interacts strongly with NodF revealed high similarity to NodG of Rhizobium sp. N33 and to NodG of Sinorhizobium meliloti We cloned and sequenced the gene coding for the NodG-like protein of R. leguminosarum and found it to be the product of the constitutively expressed gene fabG. FabG is the 3-oxoacyl-acyl carrier protein reductase that catalyzes the first reduction step in each cycle of fatty acid elongation. FabG of R. leguminosarum and NodG of Rhizobium sp. N33 were expressed in Escherichia coli. In both cases, the purified protein showed 3-oxoacyl-acyl carrier protein reductase activity in vitro. Therefore, NodG has the same biochemical function as FabG, and the high degree of similarity at the protein and DNA level suggest that nodG is a duplication of the housekeeping genefabG.
Collapse
Affiliation(s)
- I M López-Lara
- Centro de Investigación sobre Fijación de Nitrógeno, Universidad Nacional Autónoma de México, Morelos, CP.
| | | |
Collapse
|
14
|
Kiriukhin MY, Neuhaus FC. D-alanylation of lipoteichoic acid: role of the D-alanyl carrier protein in acylation. J Bacteriol 2001; 183:2051-8. [PMID: 11222605 PMCID: PMC95102 DOI: 10.1128/jb.183.6.2051-2058.2001] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The D-alanylation of membrane-associated lipoteichoic acid (LTA) in gram-positive organisms requires the D-alanine-D-alanyl carrier protein ligase (AMP) (Dcl) and the D-alanyl carrier protein (Dcp). The dlt operon encoding these proteins (dltA and dltC) also includes dltB and dltD. dltB encodes a putative transport system, while dltD encodes a protein which facilitates the binding of Dcp and Dcl for ligation with D-alanine and has thioesterase activity for mischarged D-alanyl-acyl carrier proteins (ACPs). In previous results it was shown that D-alanyl-Dcp donates its ester residue to membrane-associated LTA (M. P. Heaton and F. C. Neuhaus, J. Bacteriol. 176: 681-690, 1994). However, all efforts to identify an enzyme which catalyzes this D-alanylation process were unsuccessful. It was discovered that incubation of D-alanyl-Dcp in the presence of LTA resulted in the time-dependent hydrolysis of this D-alanyl thioester. D-Alanyl-ACP in the presence of LTA was not hydrolyzed. When Dcp was incubated with membrane-associated D-alanyl LTA, a time and concentration-dependent formation of D-alanyl-Dcp was found. The addition of NaCl to this reaction inhibited the formation of D-alanyl-Dcp and stimulated the hydrolysis of D-alanyl-Dcp. Since these reactions are specific for the carrier protein (Dcp), it is suggested that Dcp has a unique binding site which interacts with the poly(Gro-P) moiety of LTA. It is this specific interaction that provides the functional specificity for the D-alanylation process. The reversibility of this process provides a mechanism for the transacylation of the D-alanyl ester residues between LTA and wall teichoic acid.
Collapse
Affiliation(s)
- M Y Kiriukhin
- Department of Biochemistry, Molecular Biology, and Cell Biology, Northwestern University, Evanston, Illinois 60208-3500, USA
| | | |
Collapse
|