The Helicobacter pylori gene encoding phosphatidylserine synthase: sequence, expression, and insertional mutagenesis

Ge, Zhongming; Taylor, Diane E.

doi:10.1128/jb.179.16.4970-4976.1997

Cited by 22 publications

(11 citation statements)

References 50 publications

(45 reference statements)

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“…S. cerevisiae cannot grow without it, and similarly, Ge and Taylor (21) were not able to construct an H. pylori mutant deficient in Pss, indicating that PE might be essential for this organism. In contrast, an Agrobacterium mutant deficient in Pss seemed to be unaffected in growth (25).…”

Section: Discussionmentioning

confidence: 99%

“…Type II Pss were originally thought to be specific for gram-positive bacteria (32), but recent experimental data (21,25,39) and the wealth of information provided by the large number of genome projects indicate that type II Pss occur in all three kingdoms of life (archaea, eubacteria, eukaryotes) (Fig. 8).…”

Section: Discussionmentioning

confidence: 99%

“…A gene coding for the Pss enzyme (pssA) has been found and cloned in prokaryotes (10,21,41), lower eukaryotes like Saccharomyces cerevisiae (29,40), and plants (11). Pss is responsible for the formation of phosphatidylserine from CDP-diacylglycerol and serine (EC 2.7.8.8).…”

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confidence: 99%

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Phosphatidylethanolamine Is Not Essential for Growth of Sinorhizobium meliloti on Complex Culture Media

2004

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In addition to phosphatidylglycerol (PG), cardiolipin (CL), and phosphatidylethanolamine (PE), Sinorhizobium meliloti also possesses phosphatidylcholine (PC) as a major membrane lipid. The biosynthesis of PC in S. meliloti can occur via two different routes, either via the phospholipid N-methylation pathway, in which PE is methylated three times in order to obtain PC, or via the phosphatidylcholine synthase (Pcs) pathway, in which choline is condensed with CDP-diacylglycerol to obtain PC directly. Therefore, for S. meliloti, PC biosynthesis can occur via PE as an intermediate or via a pathway that is independent of PE, offering the opportunity to uncouple PC biosynthesis from PE biosynthesis. In this study, we investigated the first step of PE biosynthesis in S. meliloti catalyzed by phosphatidylserine synthase (PssA). A sinorhizobial mutant lacking PE was complemented with an S. meliloti gene bank, and the complementing DNA was sequenced. The gene coding for the sinorhizobial phosphatidylserine synthase was identified, and it belongs to the type II phosphatidylserine synthases. Inactivation of the sinorhizobial pssA gene leads to the inability to form PE, and such a mutant shows a greater requirement for bivalent cations than the wild type. A sinorhizobial PssA-deficient mutant possesses only PG, CL, and PC as major membrane lipids after growth on complex medium, but it grows nearly as well as the wild type under such conditions. On minimal medium, however, the PE-deficient mutant shows a drastic growth phenotype that can only partly be rescued by choline supplementation. Therefore, although choline permits Pcs-dependent PC formation in the mutant, it does not restore wild-typelike growth in minimal medium, suggesting that it is not only the lack of PC that leads to this drastic growth phenotype.Rhizobia are soil bacteria that are able to form a symbiosis with legume plants that leads to the formation of nitrogenfixing root nodules. The formation and functioning of this symbiosis are based on specific recognition of signal molecules, which are produced by both the bacterium and the plant partner. Recognition factors of the bacterial endosymbiont include lipochitin oligosaccharides or nodulation (Nod) factors, extracellular polysaccharides, lipopolysaccharides, K-antigens, and cyclic glucans (55), and these factors are required for nodule formation, the infection process, and the colonization of the root nodule. Recently it was demonstrated that adequate levels of certain bacterial membrane lipids, i.e., phosphatidylcholine (PC), also are required in order to allow the formation of a fully functional symbiosis between Bradyrhizobium japonicum and its host plant soybean (38). Under conditions of phosphate limitation, phosphorus-free membrane lipids (sulfolipids, ornithine-containing lipids, and diacylglyceryl-N,N,N-trimethylhomoserine lipids) are formed in rhizobia (22). Rhizobial mutants lacking the ability to form any one of these phosphorusfree membrane lipids form effective nitrogen-fixing root nodules (31), ...

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Phosphatidylethanolamine Is Not Essential for Growth of Sinorhizobium meliloti on Complex Culture Media

2004

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“…3B and 4). The only other report of such an enzyme in a gram-negative bacterium is in H. pylori (22). However, database searches show that Pss AG homologues occur not only in Rhizobiaceae (Fig.…”

Section: Discussionmentioning

confidence: 99%

Cloning and Characterization of the Phosphatidylserine Synthase Gene of Agrobacterium sp. Strain ATCC 31749 and Effect of Its Inactivation on Production of High-Molecular-Mass (1→3)-β- d -Glucan (Curdlan)

Karnezis¹,

Fisher²,

Neumann³

et al. 2002

J Bacteriol

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Genes involved in the production of the extracellular (133)-␤-glucan, curdlan, by Agrobacterium sp. strain ATCC 31749 were described previously (Stasinopoulos et al., Glycobiology 9:31-41, 1999). To identify additional curdlan-related genes whose protein products occur in the cell envelope, the transposon TnphoA was used as a specific genetic probe. One mutant was unable to produce high-molecular-mass curdlan when a previously uncharacterized gene, pss AG , encoding a 30-kDa, membrane-associated phosphatidylserine synthase was disrupted. The membranes of the mutant lacked phosphatidylethanolamine (PE), whereas the phosphatidylcholine (PC) content was unchanged and that of both phosphatidylglycerol and cardiolipin was increased. In the mutant, the continued appearance of PC revealed that its production by this Agrobacterium strain is not solely dependent on PE in a pathway controlled by the Pss AG protein at its first step. Moreover, PC can be produced in a medium lacking choline. When the pss AG ::TnphoA mutation was complemented by the intact pss AG gene, both the curdlan deficiency and the phospholipid profile were restored to wild-type, demonstrating a functional relationship between these two characteristics. The effect of the changed phospholipid profile could occur through an alteration in the overall charge distribution on the membrane or a specific requirement for PE for the folding into or maintenance of an active conformation of any or all of the structural proteins involved in curdlan production or transport.

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“…In S. meliloti, PE is a substrate for the enzyme phospholipid N-methyltransferase (PmtA) (15), leading to the formation of PC. A gene coding for the Pss enzyme (pssA) has been found and cloned from prokaryotes (11,19,38,51), lower eukaryotes, such as Saccharomyces cerevisiae (28,37), and plants (12). In a previous work we described the construction and characterization of an S. meliloti mutant deficient in Pss (51).…”

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confidence: 99%

Sinorhizobium melilotiMutants Deficient in Phosphatidylserine Decarboxylase Accumulate Phosphatidylserine and Are Strongly Affected during Symbiosis with Alfalfa

2008

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Sinorhizobium meliloti contains phosphatidylglycerol, cardiolipin, phosphatidylcholine, and phosphatidylethanolamine (PE) as major membrane lipids. PE is formed in two steps. In the first step, phosphatidylserine synthase (Pss) condenses serine with CDP-diglyceride to form phosphatidylserine (PS), and in the second step, PS is decarboxylated by phosphatidylserine decarboxylase (Psd) to form PE. In this study we identified the sinorhizobial psd gene coding for Psd. A sinorhizobial mutant deficient in psd is unable to form PE but accumulates the anionic phospholipid PS. Properties of PE-deficient mutants lacking either Pss or Psd were compared with those of the S. meliloti wild type. Whereas both PE-deficient mutants grew in a wild-type-like manner on many complex media, they were unable to grow on minimal medium containing high phosphate concentrations. Surprisingly, the psd-deficient mutant could grow on minimal medium containing low concentrations of inorganic phosphate, while the pss-deficient mutant could not. Addition of choline to the minimal medium rescued growth of the pss-deficient mutant, CS111, to some extent but inhibited growth of the psd-deficient mutant, MAV01. When the two distinct PE-deficient mutants were analyzed for their ability to form a nitrogen-fixing root nodule symbiosis with their alfalfa host plant, they behaved strikingly differently. The Pss-deficient mutant, CS111, initiated nodule formation at about the same time point as the wild type but did form about 30% fewer nodules than the wild type. In contrast, the PS-accumulating mutant, MAV01, initiated nodule formation much later than the wild type and formed 90% fewer nodules than the wild type. The few nodules formed by MAV01 seemed to be almost devoid of bacteria and were unable to fix nitrogen. Leaves of alfalfa plants inoculated with the mutant MAV01 were yellowish, indicating that the plants were starved for nitrogen. Therefore, changes in lipid composition, including the accumulation of bacterial PS, prevent the establishment of a nitrogen-fixing root nodule symbiosis.Rhizobia are soil bacteria able to form a symbiosis with legume plants, which leads to the formation of nitrogen-fixing root nodules. The establishment and functioning of this symbiosis are based on the recognition of signal molecules, which are produced by both the bacterial and plant partners. Known recognition factors of the bacterial endosymbiont include nodulation (Nod) factors, extracellular polysaccharides, lipopolysaccharides, K antigens, and cyclic glucans (24, 53). These factors are required for nodule formation, the infection process, and the colonization of the root nodule. Recently it was demonstrated that adequate levels of phosphatidylcholine (PC) are also required in order to allow the formation of a fully functional symbiosis between Bradyrhizobium japonicum and its soybean host plant (35). Under conditions of phosphate limitation, Sinorhizobium meliloti replaces the majority of its phospholipids with phosphorus-free membrane lipids, such as sulfol...

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The Helicobacter pylori gene encoding phosphatidylserine synthase: sequence, expression, and insertional mutagenesis

Cited by 22 publications

References 50 publications

Phosphatidylethanolamine Is Not Essential for Growth of Sinorhizobium meliloti on Complex Culture Media

Phosphatidylethanolamine Is Not Essential for Growth of Sinorhizobium meliloti on Complex Culture Media

Cloning and Characterization of the Phosphatidylserine Synthase Gene of Agrobacterium sp. Strain ATCC 31749 and Effect of Its Inactivation on Production of High-Molecular-Mass (1→3)-β- d -Glucan (Curdlan)

Sinorhizobium melilotiMutants Deficient in Phosphatidylserine Decarboxylase Accumulate Phosphatidylserine and Are Strongly Affected during Symbiosis with Alfalfa

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