Synthesis of the Compatible Solute Ectoine in
            <i>Virgibacillus pantothenticus</i>
            Is Triggered by High Salinity and Low Growth Temperature

Kuhlmann, Anne U.; Bursy, Jan; Gimpel, Silvy; Hoffmann, Tamara; Bremer, Erhard

doi:10.1128/aem.00492-08

Cited by 70 publications

(71 citation statements)

References 28 publications

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“…Ectoine is an osmotic agent (compatible solute) present in halophilic or halotolerant organisms. Ectoine can also serve as a protective agent for proteins in response to thermal stress (see Kuhlmann et al [48] and references therein). Because cells can tolerate ectoine at high concentrations, it may also serve as a reserve source of carbon and energy.…”

Section: Branches Of the Ask Networkmentioning

confidence: 99%

Cohesion Group Approach for Evolutionary Analysis of Aspartokinase, an Enzyme That Feeds a Branched Network of Many Biochemical Pathways

Bonner

Xie

et al. 2009

Microbiol Mol Biol Rev

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SUMMARY Aspartokinase (Ask) exists within a variable network that supports the synthesis of 9 amino acids and a number of other important metabolites. Lysine, isoleucine, aromatic amino acids, and dipicolinate may arise from the ASK network or from alternative pathways. Ask proteins were subjected to cohesion group analysis, a methodology that sorts a given protein assemblage into groups in which evolutionary continuity is assured. Two subhomology divisions, ASKα and ASKβ, have been recognized. The ASKα subhomology division is the most ancient, being widely distributed throughout the Archaea and Eukarya and in some Bacteria. Within an indel region of about 75 amino acids near the N terminus, ASKβ sequences differ from ASKα sequences by the possession of a proposed ancient deletion. ASKβ sequences are present in most Bacteria and usually exhibit an in-frame internal translational start site that can generate a small Ask subunit that is identical to the C-terminal portion of the larger subunit of a heterodimeric unit. Particularly novel are ask genes embedded in gene contexts that imply specialization for ectoine (osmotic agent) or aromatic amino acids. The cohesion group approach is well suited for the easy recognition of relatively recent lateral gene transfer (LGT) events, and many examples of these are described. Given the current density of genome representation for Proteobacteria, it is possible to reconstruct more ancient landmark LGT events. Thus, a plausible scenario in which the three well-studied and iconic Ask homologs of Escherichia coli are not within the vertical genealogy of Gammaproteobacteria, but rather originated via LGT from a Bacteroidetes donor, is supported.

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Section: Branches Of the Ask Networkmentioning

confidence: 99%

Cohesion Group Approach for Evolutionary Analysis of Aspartokinase, an Enzyme That Feeds a Branched Network of Many Biochemical Pathways

Bonner

Xie

et al. 2009

Microbiol Mol Biol Rev

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“…We showed using one-dimension 1 H nuclear magnetic resonance spectroscopy ( 1 H-NMR) that at high salinity V. parahaemolyticus is capable of de novo synthesis of ectoine whereas a ⌬ectB strain is not (25). In a broader context, it has been shown that compatible solutes and solute activities can protect against nonosmotic stresses, for example high-pressure stress can be countered by kosmotropes (36), while some studies have shown that compatible solutes can crossprotect against heat and cold-temperature stress (27,37,38).…”

mentioning

confidence: 99%

Biosynthesis of the Osmoprotectant Ectoine, but Not Glycine Betaine, Is Critical for Survival of Osmotically Stressed Vibrio parahaemolyticus Cells

Ongagna-Yhombi

Boyd

2013

Appl Environ Microbiol

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Vibrio parahaemolyticus is a halophile present in marine and estuarine environments, ecosystems characterized by fluctuations in salinity and temperature. One strategy to thrive in such environments is the synthesis and/or uptake of compatible solutes. The V. parahaemolyticus genome contains biosynthesis systems for both ectoine and glycine betaine, which are known to act as compatible solutes in other species. We showed that V. parahaemolyticus had a 6% NaCl tolerance when grown in M9 minimal medium with 0.4% glucose (M9G) with a >5-h lag phase. By using 1 H nuclear magnetic resonance spectroscopy ( 1 H-NMR) analysis, we determined that cells synthesized ectoine and glutamate in a NaCl-dependent manner. The most effective compatible solutes as measured by a reduction in lag-phase growth in M9G with 6% NaCl (M9G 6% NaCl) were in the order glycine betaine > choline > proline ‫؍‬ glutamate > ectoine. However, V. parahaemolyticus could use glutamate or proline as the sole carbon source, but not ectoine or glycine betaine, which suggests that these are bona fide compatible solutes. Expression analysis showed that the ectA and betA genes were more highly expressed in log-phase cells, and expression of both genes was induced by NaCl up-shock. Under all conditions examined, the ectA gene was more highly expressed than the betA gene. Analysis of inframe deletions in betA and ectB and in a double mutant showed that the ectB mutant was defective for growth, and this defect was rescued by the addition of glycine betaine, proline, ectoine, and glutamate, indicating that these compounds are compatible solutes for this species. The presence of both synthesis systems was the predominant distribution pattern among members of the Vibrionaceae family, suggesting this is the ancestral state.

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“…Microbial cells accumulate compatible solutes through either synthesis or uptake from environmental resources (7,65,69). They can employ them not only as effective osmostress protectants, but also as protectants against heat (8,10,13,17,26) and cold (2,25,33) stress.…”

mentioning

confidence: 99%

“…A subset of the ectoine producers hydroxylate ectoine to 5-hydroxyectoine (9,17,48) in a stereospecific fashion using the ectoine hydroxylase EctD (8,9,50). The structural genes (ectABC) for the ectoine biosynthetic enzymes are typically organized as a gene cluster whose transcription can be induced by increased osmolarity of the growth medium (9,11,32,33,40,43). In some microorganisms (e.g., in several bacilli) the ectABC genes are transcribed as an operon (8,32,33), but more complex patterns of ect transcription have been reported for Chromohalobacter salexigens (17) and Halomonas elongata (57).…”

mentioning

confidence: 99%

“…The structural genes (ectABC) for the ectoine biosynthetic enzymes are typically organized as a gene cluster whose transcription can be induced by increased osmolarity of the growth medium (9,11,32,33,40,43). In some microorganisms (e.g., in several bacilli) the ectABC genes are transcribed as an operon (8,32,33), but more complex patterns of ect transcription have been reported for Chromohalobacter salexigens (17) and Halomonas elongata (57). The ectABC operon might also contain the structural gene (ectD) for the ectoine hydroxylase (8,48), but this gene can often also be found in a genomic location unlinked from the ectoine biosynthetic gene cluster (9,17).…”

mentioning

confidence: 99%

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A Specialized Aspartokinase Enhances the Biosynthesis of the Osmoprotectants Ectoine and Hydroxyectoine in Pseudomonas stutzeriA1501

et al. 2011

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The compatible solutes ectoine and hydroxyectoine are widely produced by bacteria as protectants against osmotic and temperature stress. L-Aspartate-beta-semialdehyde is used as the precursor molecule for ectoine/ hydroxyectoine biosynthesis that is catalyzed by the EctABCD enzymes. L-Aspartate-beta-semialdehyde is a central intermediate in different biosynthetic pathways and is produced from L-aspartate by aspartokinase (Ask) and aspartate-semialdehyde-dehydrogenase (Asd). Ask activity is typically stringently regulated by allosteric control to avoid gratuitous synthesis of aspartylphosphate. Many organisms have evolved multiple forms of aspartokinase, and feedback regulation of these specialized Ask enzymes is often adapted to the cognate biochemical pathways. The ectoine/hydroxyectoine biosynthetic genes (ectABCD) are followed in a considerable number of microorganisms by an ask gene (ask_ect), suggesting that Ask_Ect is a specialized enzyme for this osmoadaptive biosynthetic pathway. However, none of these Ask_Ect enzymes have been functionally characterized. Pseudomonas stutzeri A1501 synthesizes both ectoine and hydroxyectoine in response to increased salinity, and it possesses two Ask enzymes: Ask_Lys and Ask_Ect. We purified both Ask enzymes and found significant differences with regard to their allosteric control: Ask_LysC was inhibited by threonine and in a concerted fashion by threonine and lysine, whereas Ask_Ect showed inhibition only by threonine. The ectABCD_ask genes from P. stutzeri A1501 were cloned and functionally expressed in Escherichia coli, and this led to osmostress protection. An E. coli strain carrying the plasmid-based ectABCD_ask gene cluster produced significantly more ectoine/hydroxyectoine than a strain expressing the ectABCD gene cluster alone. This finding suggests a specialized role for Ask_Ect in ectoine/hydroxyectoine biosynthesis.The growth arrest of microbial cells observed under severe high-osmolarity conditions is correlated with the reduction in the amount of free cytoplasmic water (12) and the reduction or collapse of turgor (7, 65). To promote water reentry and retention under high-osmolarity growth conditions and to balance turgor, many microorganisms amass a selected class of organic osmolytes, the compatible solutes (31, 66). Microbial cells accumulate compatible solutes through either synthesis or uptake from environmental resources (7, 65, 69). They can employ them not only as effective osmostress protectants, but also as protectants against heat (8, 10, 13, 17, 26) and cold (2, 25, 33) stress.The tetrahydropyrimidines ectoine and 5-hydroxyectoine ( Fig. 1) are an important class of compatible solutes (9,45,50). Biosynthesis of ectoine is catalyzed by L-2,4-diaminobutyric acid transaminase (EctB), N-␥-acetyltransferase (EctA), and ectoine synthase (EctC) (40,44). A subset of the ectoine producers hydroxylate ectoine to 5-hydroxyectoine (9, 17, 48) in a stereospecific fashion using the ectoine hydroxylase EctD (8, 9, 50). The structural genes (ectABC) for the ectoi...

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Synthesis of the Compatible Solute Ectoine in Virgibacillus pantothenticus Is Triggered by High Salinity and Low Growth Temperature

Cited by 70 publications

References 28 publications

Cohesion Group Approach for Evolutionary Analysis of Aspartokinase, an Enzyme That Feeds a Branched Network of Many Biochemical Pathways

Cohesion Group Approach for Evolutionary Analysis of Aspartokinase, an Enzyme That Feeds a Branched Network of Many Biochemical Pathways

Biosynthesis of the Osmoprotectant Ectoine, but Not Glycine Betaine, Is Critical for Survival of Osmotically Stressed Vibrio parahaemolyticus Cells

A Specialized Aspartokinase Enhances the Biosynthesis of the Osmoprotectants Ectoine and Hydroxyectoine in Pseudomonas stutzeriA1501

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