Trimethylated homoserine functions as the major compatible solute in the globally significant oceanic cyanobacterium
            <i>Trichodesmium</i>

Pade, Nadin; Michalik, Dirk; Ruth, Wolfgang; Belkin, Natalia; Hess, Wolfgang R.; Berman‐Frank, Ilana; Hagemann, Martin

doi:10.1073/pnas.1611666113

Cited by 36 publications

(34 citation statements)

References 40 publications

(39 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Many freshwater or marine species of cyanobacteria naturally synthesize and accumulate large internal amounts of sucrose as the compatible solute when stressed by NaCl. Alternatively or additionally, other small molecules such as trehalose, glucosylglycerol, glucosylglycerate, glycine betaine, or homoserine betaine can also act as compatible solutes to protect cyanobacterial cells from osmotic stress (19,20). The main pathway for sucrose synthesis (Fig.…”

mentioning

confidence: 99%

Effects of Reduced and Enhanced Glycogen Pools on Salt-Induced Sucrose Production in a Sucrose-Secreting Strain of Synechococcus elongatus PCC 7942

Qiao

Duan

Zhang

et al. 2018

Appl Environ Microbiol

Self Cite

View full text Add to dashboard Cite

Sucrose and glycogen syntheses in cyanobacteria share the common precursor glucose-1-phosphate. It is generally assumed that lowering glycogen synthesis could drive more carbon toward sucrose synthesis that can be induced by salt stress among cyanobacteria. By using a theophylline-dependent riboswitch system, the expression of , a key gene in glycogen synthesis, was downregulated in a quantitative manner in a sucrose-secreting strain of PCC 7942. We observed that the stepwise suppression of glycogen synthesis limited rather than stimulated sucrose production in the salt-stressed cells, suggesting that glycogen could serve as a carbon pool for the synthesis of sucrose. Accordingly, we generated glycogen-overproducing strains, but the increased glycogen pool alone did not stimulate sucrose production, indicating that alternative steps limit the carbon flux toward the synthesis of sucrose. Consistent with previous studies that showed that sucrose-phosphate synthase (SPS) catalyzes the rate-limiting step in sucrose synthesis, the combination of glycogen overproduction and overexpression resulted in increased sucrose production. Our results indicate that the glycogen and sucrose pools are closely linked in PCC 7942, and we propose that enhancing the glycogen pool could be a promising strategy for the improvement of sucrose production by cyanobacteria in the presence of a strong sucrose synthesis sink. Many cyanobacteria naturally synthesize and accumulate sucrose when stressed by NaCl, which provides novel possibilities for obtaining sugar feedstock by engineering of cyanobacteria. It has been assumed that glycogen synthesis competes with sucrose synthesis for the carbon flux. However, our results showed that the suppression of glycogen synthesis decreased rather than stimulated sucrose production in a sucrose-secreting strain of PCC 7942. This result suggests that glycogen could serve as a supportive rather than a competitive carbon pool for the synthesis of sucrose, providing new insights about the relation between glycogen synthesis and sucrose synthesis in cyanobacteria. This finding is also useful to guide metabolic engineering work to optimize the production of sucrose and possibly other products by cyanobacteria.

show abstract

mentioning

confidence: 99%

Effects of Reduced and Enhanced Glycogen Pools on Salt-Induced Sucrose Production in a Sucrose-Secreting Strain of Synechococcus elongatus PCC 7942

Qiao

Duan

Zhang

et al. 2018

Appl Environ Microbiol

Self Cite

View full text Add to dashboard Cite

show abstract

“…Growth rates declined, although biomass still increased, when ambient salinity was increased to 43 ppt (Figs. 1a, b ) [ 38 ], while growth was severely inhibited at 48 ppt salinity, as shown by the spectral scan of pigments (Figure S1 ). Although Trichodesmium also thrives in high salinity waters such as in the Gulf of Aqaba (Red Sea; salinity ~40.8) [ 52 , 53 ], our data show that salinities ≥43 ppt induce great stress, declining growth rates, and enhanced mortality.…”

Section: Resultsmentioning

confidence: 99%

“…After adapter removal and quality trimming, >40 million and 18 million reads were generated for each of the dRNA-Seq and minus libraries, separately. Details of RNA isolation and library preparation were presented previously [ 38 , 39 ].…”

Section: Methodsmentioning

confidence: 99%

Benefit from decline: the primary transcriptome of Alteromonas macleodii str. Te101 during Trichodesmium demise

et al. 2018

Self Cite

View full text Add to dashboard Cite

Interactions between co-existing microorganisms deeply affect the physiology of the involved organisms and, ultimately, the function of the ecosystem as a whole. Copiotrophic Alteromonas are marine gammaproteobacteria that thrive during the late stages of phytoplankton blooms in the marine environment and in laboratory co-cultures with cyanobacteria such as Trichodesmium. The response of this heterotroph to the sometimes rapid and transient changes in nutrient supply when the phototroph crashes is not well understood. Here, we isolated and sequenced the strain Alteromonas macleodii str. Te101 from a laboratory culture of Trichodesmium erythraeum IMS101, yielding a chromosome of 4.63 Mb and a single plasmid of 237 kb. Increasing salinities to ≥43 ppt inhibited the growth of Trichodesmium but stimulated growth of the associated Alteromonas. We characterized the transcriptomic responses of both microorganisms and identified the complement of active transcriptional start sites in Alteromonas at single-nucleotide resolution. In replicate cultures, a similar set of genes became activated in Alteromonas when growth rates of Trichodesmium declined and mortality was high. The parallel activation of fliA, rpoS and of flagellar assembly and growth-related genes indicated that Alteromonas might have increased cell motility, growth, and multiple biosynthetic activities. Genes with the highest expression in the data set were three small RNAs (Aln1a-c) that were identified as analogs of the small RNAs CsrB-C in E. coli or RsmX-Z in pathogenic bacteria. Together with the carbon storage protein A (CsrA) homolog Te101_05290, these RNAs likely control the expression of numerous genes in responding to changes in the environment.

show abstract

“…One of these mechanisms is to produce compatible solutes in the cytoplasm . When stressed by sodium chloride (NaCl), cyanobacterial cells synthesize and accumulate high internal amounts of small organic compounds including sucrose, trehalose, glucosylglycerol, glucosylglycerate, glycine betaine, and homoserine betaine to protect cells against osmotic stress . Some of these small molecules are interesting products, since they can be used for food additives such as trehalose and sucrose, human nutrition such as sucrose, and moisturizing agents in skin care products such as trehalose and glucosylglycerol .…”

Section: Introductionmentioning

confidence: 99%

Identification of two two‐component signal transduction mutants with enhanced sucrose biosynthesis in Synechococcus elongatus PCC 7942

et al. 2019

View full text Add to dashboard Cite

Metabolic engineering of the freshwater cyanobacterium Synechococcus elongatus PCC 7942 (Syn7942), synthesizing sucrose as the only compatible solute upon salt stress, has greatly improved its sucrose productivity. However, the signaling and regulatory mechanisms of this physiological process are still unknown. To know more about these aspects, a library of inactivation mutants for all 44 predicted signal transduction genes of Syn7942 was constructed. By evaluating sucrose production, two two-component signal transduction mutants Δ1125 and Δ1404, in which Synpcc7942_1125 and Synpcc7942_1404 was inactivated, respectively, were identified. They exhibited stably enhanced sucrose production, but the growth and the expression of sps encoding sucrose-phosphate synthase under salt stress were not affected, indicating that the corresponding signal transduction proteins do not regulate salt-induced sucrose synthesis by directly regulating sps expression. Moreover, the glycogen accumulation was enhanced in Δ1125 and Δ1404, and the salt stressintensified photodamage of these mutants was also found to be relieved. These results indicated that the basic cell metabolisms such as glycogen metabolism and photosynthesis of the mutants were affected by gene inactivation, which might further affect salt-induced sucrose synthesis. Further studies on gene functions and signaling pathways or networks of Synpcc7942_1125 and Synpcc7942_1404 would reveal more details about the molecular bases for the observed phenotypes of Δ1125 and Δ1404. K E Y W O R D Ssalt stress, signal transduction, sucrose biosynthesis, Synechococcus elongatus PCC 7942

show abstract

Trimethylated homoserine functions as the major compatible solute in the globally significant oceanic cyanobacterium Trichodesmium

Cited by 36 publications

References 40 publications

Effects of Reduced and Enhanced Glycogen Pools on Salt-Induced Sucrose Production in a Sucrose-Secreting Strain of Synechococcus elongatus PCC 7942

Effects of Reduced and Enhanced Glycogen Pools on Salt-Induced Sucrose Production in a Sucrose-Secreting Strain of Synechococcus elongatus PCC 7942

Benefit from decline: the primary transcriptome of Alteromonas macleodii str. Te101 during Trichodesmium demise

Identification of two two‐component signal transduction mutants with enhanced sucrose biosynthesis in Synechococcus elongatus PCC 7942

Contact Info

Product

Resources

About