Two Trk/Ktr/HKT-type potassium transporters, TrkG and TrkH, perform distinct functions in Escherichia coli K-12

Tanudjaja, Ellen; Hoshi, Naomi; Ihara, Kenji; Furuta, Tadaomi; Tsujii, Masaru; Ishimaru, Yasuhiro; Uozumi, Nobuyuki

doi:10.1016/j.jbc.2022.102846

Cited by 6 publications

(4 citation statements)

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“…4 a, e, and 5 a). It has been found that the transcriptional levels of the two membrane transporters (TrkH and TrkG) of the Trk-type K + transport system were not significantly affected by the concentration of NaCl (0–1000 mM) [ 81 ]. Therefore, the increased relative abundance of the Trk-type K + transport system with rising salinity may indicate a response of the estuarine microbial communities to osmotic stress.…”

Section: Discussionmentioning

confidence: 99%

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Metagenomic insights into microbial adaptation to the salinity gradient of a typical short residence-time estuary

Wu,

Li,

et al. 2024

Microbiome

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Background Microbial adaptation to salinity has been a classic inquiry in the field of microbiology. It has been demonstrated that microorganisms can endure salinity stress via either the “salt-in” strategy, involving inorganic ion uptake, or the “salt-out” strategy, relying on compatible solutes. While these insights are mostly based on laboratory-cultured isolates, exploring the adaptive mechanisms of microorganisms within natural salinity gradient is crucial for gaining a deeper understanding of microbial adaptation in the estuarine ecosystem. Results Here, we conducted metagenomic analyses on filtered surface water samples collected from a typical subtropical short residence-time estuary and categorized them by salinity into low-, intermediate-, and high-salinity metagenomes. Our findings highlighted salinity-driven variations in microbial community composition and function, as revealed through taxonomic and Clusters of Orthologous Group (COG) functional annotations. Through metagenomic binning, 127 bacterial and archaeal metagenome-assembled genomes (MAGs) were reconstructed. These MAGs were categorized as stenohaline—specific to low-, intermediate-, or high-salinity—based on the average relative abundance in one salinity category significantly exceeding those in the other two categories by an order of magnitude. Those that did not meet this criterion were classified as euryhaline, indicating a broader range of salinity tolerance. Applying the Boruta algorithm, a machine learning-based feature selection method, we discerned important genomic features from the stenohaline bacterial MAGs. Of the total 12,162 COGs obtained, 40 were identified as important features, with the “inorganic ion transport and metabolism” COG category emerging as the most prominent. Furthermore, eight COGs were implicated in microbial osmoregulation, of which four were related to the “salt-in” strategy, three to the “salt-out” strategy, and one to the regulation of water channel activity. COG0168, annotated as the Trk-type K+ transporter related to the “salt-in” strategy, was ranked as the most important feature. The relative abundance of COG0168 was observed to increase with rising salinity across metagenomes, the stenohaline strains, and the dominant Actinobacteriota and Proteobacteria phyla. Conclusions We demonstrated that salinity exerts influences on both the taxonomic and functional profiles of the microbial communities inhabiting the estuarine ecosystem. Our findings shed light on diverse salinity adaptation strategies employed by the estuarine microbial communities, highlighting the crucial role of the “salt-in” strategy mediated by Trk-type K+ transporters for microorganisms thriving under osmotic stress in the short residence-time estuary.

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Section: Discussionmentioning

confidence: 99%

“…This is possibly due to TrkH-mediated K + uptake being unaffected by Na + in the estuarine aquatic environment. A potential explanation for TrkG being annotated in all MAGs of Cyanobacteria is that the intake of Na + is beneficial for their growth, as TrkG transports not only K + but also Na + [ 81 ].…”

Section: Discussionmentioning

confidence: 99%

Metagenomic insights into microbial adaptation to the salinity gradient of a typical short residence-time estuary

Wu,

Li,

et al. 2024

Microbiome

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“…1 ). TrkG, an ancestor of Trk/Ktr/HKT in Escherichia coli , can transport both Na + and K + , and K + transport assists cell growth ( 21 ). AtHKT1;1 also has K + uptake transport activity ( 27 ), which supplies the major element K + to the cells.…”

Section: Discussionmentioning

confidence: 99%

“…A different type of Na + transport system, Na + transport system, AtHKT1;1, which is involved in conferring Na + tolerance, has been identified (16)(17)(18)(19). High affinity K transporters (HKTs) belong to the Trk/Ktr/HKT family, a K + and/or Na + uptake system that is found in a wide range of organisms (20,21). During the vegetative stage, AtHKT1;1 function is important in xylem parenchyma cells and for Na + unloading from xylem in roots (18,19).…”

Section: Introductionmentioning

confidence: 99%

The HKT1 Na ⁺ transporter protects plant fertility by decreasing Na ⁺ content in stamen filaments

et al. 2023

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Salinity stress can greatly reduce seed production because plants are especially sensitive to salt during their reproductive stage. Here, we show that the sodium ion transporter AtHKT1;1 is specifically expressed around the phloem and xylem of the stamen in Arabidopsis thaliana to prevent a marked decrease in seed production caused by salt stress. The stamens of AtHKT1;1 mutant under salt stress overaccumulate Na + , limiting their elongation and resulting in male sterility. Specifically restricting AtHKT1;1 expression to the phloem leads to a 1.5-fold increase in the seed yield upon sodium ion stress. Expanding phloem expression of AtHKT1;1 throughout the entire plant is a promising strategy for increasing plant productivity under salinity stress.

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Insights into plant salt stress signaling and tolerance

Zhou,

Shi,

Yang

et al. 2024

Journal of Genetics and Genomics

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Two Trk/Ktr/HKT-type potassium transporters, TrkG and TrkH, perform distinct functions in Escherichia coli K-12

Cited by 6 publications

References 86 publications

Metagenomic insights into microbial adaptation to the salinity gradient of a typical short residence-time estuary

Metagenomic insights into microbial adaptation to the salinity gradient of a typical short residence-time estuary

The HKT1 Na ⁺ transporter protects plant fertility by decreasing Na ⁺ content in stamen filaments

Insights into plant salt stress signaling and tolerance

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Two Trk/Ktr/HKT-type potassium transporters, TrkG and TrkH, perform distinct functions in Escherichia coli K-12

Cited by 6 publications

References 86 publications

Metagenomic insights into microbial adaptation to the salinity gradient of a typical short residence-time estuary

Metagenomic insights into microbial adaptation to the salinity gradient of a typical short residence-time estuary

The HKT1 Na + transporter protects plant fertility by decreasing Na + content in stamen filaments

Insights into plant salt stress signaling and tolerance

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The HKT1 Na ⁺ transporter protects plant fertility by decreasing Na ⁺ content in stamen filaments