Potassium uptake in the unicellular cyanobacterium Synechocystis sp. strain PCC 6803 mainly depends on a Ktr‐like system encoded by slr1509 (ntpJ)

Berry, Stephan; Esper, Berndt; Karandashova, I. V.; Teuber, Markus; Elanskaya, I.V.; Rögner, Matthias; Hagemann, Martin

doi:10.1016/s0014-5793(03)00729-4

Cited by 43 publications

(45 citation statements)

References 27 publications

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“…Transport Activity in E. coli-Since previous reports have suggested that Synechocystis KtrB plays a role in K ϩ uptake (20,21,30), rather than in Na ϩ transport (22, 47) (www. kazusa.or.jp/cyano/), we investigated the role of Synechocystis ktr genes in K ϩ transport and analyzed the Ktr gene family.…”

Section: Three Synechocystis Ktr Gene Products Are Required For K ϩmentioning

confidence: 99%

“…During its long term adaptation to high NaCl concentrations, this organism also synthesizes and accumulates glucosylgylcerol (17)(18)(19). Determining from the genome sequence, strain PCC 6803 has been predicted to contain at least three types of K ϩ uptake systems, Kdp system, which is probably of minor importance (20), a Ktr system (21), which appears to play a role in salt stress by high NaCl concentrations (20) and K ϩ channels. However, the Ktr system has not been characterized any further.…”

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confidence: 99%

“…Recently, Berry et al (20) indicates that ntpJ/ktrB from Synechocystis sp. PCC 6803 has a function in K ϩ uptake.…”

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confidence: 99%

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Na+-dependent K+ Uptake Ktr System from the Cyanobacterium Synechocystis sp. PCC 6803 and Its Role in the Early Phases of Cell Adaptation to Hyperosmotic Shock

Matsuda

Kobayashi

Katoh

et al. 2004

Journal of Biological Chemistry

107

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Transmembrane ion transport processes play a key role in the adaptation of cells to hyperosmotic conditions. Previous work has shown that the disruption of a ktrB/ntpJ-like putative Na ؉ /K ؉ transporter gene in the cyanobacterium Synechocystis sp. PCC 6803 confers increased Na ؉ sensitivity, and inhibits HCO 3 ؊ uptake. Here, we report on the mechanistic basis of this effect. Heterologous expression experiments in Escherichia coli show that three Synechocystis genes are required for K ؉ transport activity. They encode an NAD ؉ -binding peripheral membrane protein (ktrA; sll0493), an integral membrane protein, belonging to a superfamily of K ؉ transporters (ktrB; formerly ntpJ; slr1509), and a novel type of ktr gene product, not previously found in Ktr systems (ktrE; slr1508). In E. coli, Synechocystis KtrABEmediated K ؉ uptake occurred with a moderately high affinity (K m of about 60 M), and depended on both Na ؉ and a high membrane potential, but not on ATP. KtrABE neither mediated Na ؉ uptake nor Na ؉ efflux. In Synechocystis sp. PCC 6803, KtrB-mediated K ؉ uptake required Na ؉ and was inhibited by protonophore. A ⌬ktrB strain was sensitive to long term hyperosmotic stress elicited by either NaCl or sorbitol. Hyperosmotic shock led initially to loss of net K ؉ from the cells. The ⌬ktrB cells shocked with sorbitol failed to reaccumulate K ؉ up to its original level. These data indicate that in strain PCC 6803 K ؉ uptake via KtrABE plays a crucial role in the early phase of cell turgor regulation after hyperosmotic shock.

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Section: Three Synechocystis Ktr Gene Products Are Required For K ϩmentioning

confidence: 99%

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Na+-dependent K+ Uptake Ktr System from the Cyanobacterium Synechocystis sp. PCC 6803 and Its Role in the Early Phases of Cell Adaptation to Hyperosmotic Shock

Matsuda

Kobayashi

Katoh

et al. 2004

Journal of Biological Chemistry

107

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“…The membrane proteins in both superfamilies share the same architecture 2,5-9 : four subunits or repeats, each with the TM-P loop-TM (where TM indicates transmembrane helix) structural motif first seen in the KcsA potassium channel structure 10 , assemble to form an ion pore with a 'selectivity filter' along its central axis. In addition, the cytosolic regulatory proteins of the Trk and Ktr transporters and of the MthK 11,12 and large-conductance Ca 2+ -gated (BK) K + channels [13][14][15] are RCK (regulate conductance of K+) domains.Ktr ion transporters are crucial K + transport systems in some bacteria 16,17 , with a role in resistance to osmotic stress and high salinity by mediating the early uptake of K + (refs 16, 18). The Ktr ion transporters are composed of two essential components 3,16 : a membrane protein (KtrB or KtrD) and a cytosolic regulatory protein (KtrA or KtrC).…”

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confidence: 99%

“…Ktr ion transporters are crucial K + transport systems in some bacteria 16,17 , with a role in resistance to osmotic stress and high salinity by mediating the early uptake of K + (refs 16, 18). The Ktr ion transporters are composed of two essential components 3,16 : a membrane protein (KtrB or KtrD) and a cytosolic regulatory protein (KtrA or KtrC).…”

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The structure of the KtrAB potassium transporter

Vieira-Pires

Szöllősi

Morais-Cabral

2013

Nature

106

163

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In bacteria, archaea, fungi and plants the Trk, Ktr and HKT ion transporters are key components of osmotic regulation, pH homeostasis and resistance to drought and high salinity. These ion transporters are functionally diverse: they can function as Na + or K + channels and possibly as cation/K + symporters. They are closely related to potassium channels both at the level of the membrane protein and at the level of the cytosolic regulatory domains. Here we describe the crystal structure of a Ktr K + transporter, the KtrAB complex from Bacillus subtilis. The structure shows the dimeric membrane protein KtrB assembled with a cytosolic octameric KtrA ring bound to ATP, an activating ligand. A comparison between the structure of KtrAB-ATP and the structures of the isolated fulllength KtrA protein with ATP or ADP reveals a ligand-dependent conformational change in the octameric ring, raising new ideas about the mechanism of activation in these transporters.The Trk/Ktr/HKT superfamily of ion transporters includes the Trk, Ktr and HKT transporter families 1 . These transporters are closely related to the superfamily of tetrameric cation channels 2-4 , which includes potassium, sodium and calcium channels. The membrane proteins in both superfamilies share the same architecture 2,5-9 : four subunits or repeats, each with the TM-P loop-TM (where TM indicates transmembrane helix) structural motif first seen in the KcsA potassium channel structure 10 , assemble to form an ion pore with a 'selectivity filter' along its central axis. In addition, the cytosolic regulatory proteins of the Trk and Ktr transporters and of the MthK 11,12 and large-conductance Ca 2+ -gated (BK) K + channels [13][14][15] are RCK (regulate conductance of K+) domains.Ktr ion transporters are crucial K + transport systems in some bacteria 16,17 , with a role in resistance to osmotic stress and high salinity by mediating the early uptake of K + (refs 16, 18). The Ktr ion transporters are composed of two essential components 3,16 : a membrane protein (KtrB or KtrD) and a cytosolic regulatory protein (KtrA or KtrC). Studies with cells show that Ktr proteins 8,19 transport K + but are also permeable to Na + , and that K + transport is ATP 20 and Na + dependent 5,8,18 . Furthermore, it has been shown that truncated KtrA forms octameric rings 21,22 and that KtrB assembles as homodimers 6,21 . The structures described here clarify the molecular basis of some of these properties as well as the structural relationship between these transporters and ion channels.

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Inorganic Carbon Assimilation in Cyanobacteria: Mechanisms, Regulation, and Engineering

Hagemann

Song

Brouwer

2021

Cyanobacteria Biotechnology

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Potassium uptake in the unicellular cyanobacterium Synechocystis sp. strain PCC 6803 mainly depends on a Ktr‐like system encoded by slr1509 (ntpJ)

Cited by 43 publications

References 27 publications

Na+-dependent K+ Uptake Ktr System from the Cyanobacterium Synechocystis sp. PCC 6803 and Its Role in the Early Phases of Cell Adaptation to Hyperosmotic Shock

Na+-dependent K+ Uptake Ktr System from the Cyanobacterium Synechocystis sp. PCC 6803 and Its Role in the Early Phases of Cell Adaptation to Hyperosmotic Shock

The structure of the KtrAB potassium transporter

Inorganic Carbon Assimilation in Cyanobacteria: Mechanisms, Regulation, and Engineering

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