Mg2+-dependent gating of bacterial MgtE channel underlies Mg2+ homeostasis

Hattori, Motoyuki; Iwase, Norihiko; Furuya, Noritaka; Tanaka, Yoshiki; Tsukazaki, Tomoya; Ishitani, Ryuichiro; Maguire, Michael E.; Ito, Koichi; Maturana, Andrés D.; Nureki, Osamu

doi:10.1038/emboj.2009.288

Cited by 92 publications

(205 citation statements)

References 37 publications

(59 reference statements)

Supporting

Mentioning

188

Contrasting

Order By: Relevance

“…In both TmCorA and MgtE, the involvement of the metal ion binding sites in the regulation of gating has been further confirmed by biochemical studies (15,22) and molecular dynamics simulations (11,23). Based on these studies, the suggested gating mechanism for TmCorA proposes that a hydrophobic gate, sufficiently wide to allow the passage of hydrated Mg 2+ , closes as the result of a decrease in the pore size upon Mg 2+ binding to the aforementioned binding sites (11).…”

Section: Resultsmentioning

confidence: 85%

Structural insights into the mechanisms of Mg ²⁺ uptake, transport, and gating by CorA

Guskov

Nordin

Reynaud

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

Despite the importance of Mg 2+ for numerous cellular activities, the mechanisms underlying its import and homeostasis are poorly understood. The CorA family is ubiquitous and is primarily responsible for Mg 2+ transport. However, the key questions-such as, the ion selectivity, the transport pathway, and the gating mechanism-have remained unanswered for this protein family. We present a 3.2 Å resolution structure of the archaeal CorA from Methanocaldococcus jannaschii, which is a unique complete structure of a CorA protein and reveals the organization of the selectivity filter, which is composed of the signature motif of this family. The structure reveals that polar residues facing the channel coordinate a partially hydrated Mg 2+ during the transport. Based on these findings, we propose a unique gating mechanism involving a helical turn upon the binding of Mg 2+ to the regulatory intracellular binding sites, and thus converting a polar ion passage into a narrow hydrophobic pore. Because the amino acids involved in the uptake, transport, and gating are all conserved within the entire CorA family, we believe this mechanism is general for the whole family including the eukaryotic homologs.

show abstract

Section: Resultsmentioning

confidence: 85%

Structural insights into the mechanisms of Mg ²⁺ uptake, transport, and gating by CorA

Guskov

Nordin

Reynaud

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…For example, Mg 2þ binding to the Bateman domain dimer of the bacterial channel Mg 2þ MgtE induces an open-to-closed conformational change by shielding the charge-charge repulsion of acidic amino acid residues (22,45,47). By analogy with MgtE, binding and unbinding Values are means 5 SE (n).…”

Section: Discussionmentioning

confidence: 99%

Role of CBS and Bateman Domains in Phosphorylation-Dependent Regulation of a CLC Anion Channel

Yamada

Krzeminski

Bozóky

et al. 2016

Biophysical Journal

View full text Add to dashboard Cite

Eukaryotic CLC anion channels and transporters are homodimeric proteins composed of multiple a-helical membrane domains and large cytoplasmic C-termini containing two cystathionine-b-synthase domains (CBS1 and CBS2) that dimerize to form a Bateman domain. The Bateman domains of adjacent CLC subunits interact to form a Bateman domain dimer. The functions of CLC CBS and Bateman domains are poorly understood. We utilized the Caenorhabditis elegans CLC-1/2/Ka/ Kb anion channel homolog CLH-3b to characterize the regulatory roles of CLC cytoplasmic domains. CLH-3b activity is reduced by phosphorylation or deletion of a 14-amino-acid activation domain (AD) located on the linker connecting CBS1 and CBS2. We demonstrate here that phosphorylation-dependent reductions in channel activity require an intact Bateman domain dimer and concomitant phosphorylation or deletion of both ADs. Regulation of a CLH-3b AD deletion mutant is reconstituted by intracellular perfusion with recombinant 14-amino-acid AD peptides. The sulfhydryl reactive reagent 2-(trimethylammonium)ethyl methanethiosulfonate bromide (MTSET) alters in a phosphorylation-dependent manner the activity of channels containing single cysteine residues that are engineered into the short intracellular loop connecting membrane a-helices H and I (H-I loop), the AD, CBS1, and CBS2. In contrast, MTSET has no effect on channels in which cysteine residues are engineered into intracellular regions that are dispensable for regulation. These studies together with our previous work suggest that binding and unbinding of the AD to the Bateman domain dimer induces conformational changes that are transduced to channel membrane domains via the H-I loop. Our findings provide new, to our knowledge, insights into the roles of CLC Bateman domains and the structurefunction relationships that govern the regulation of CLC protein activity by diverse ligands and signaling pathways.

show abstract

“…To test for competency in Mg 2+ transport, expression plasmids for WT and mutant TmCorA were transformed into Escherichia coli strain BW25113 as published (38). Figures of proteins were generated with PYMOL (DeLano Scientific).…”

Section: Methodsmentioning

confidence: 99%

Structural asymmetry in the magnesium channel CorA points to sequential allosteric regulation

Pfoh

Li²,

Chakrabarti

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

135

View full text Add to dashboard Cite

Magnesium ions (Mg 2+ ) are essential for life, but the mechanisms regulating their transport into and out of cells remain poorly understood. The CorA-Mrs2-Alr1 superfamily of Mg 2+ channels represents the most prevalent group of proteins enabling Mg 2+ ions to cross membranes. Thermotoga maritima CorA (TmCorA) is the only member of this protein family whose complete 3D fold is known. Here, we report the crystal structure of a mutant in the presence and absence of divalent ions and compare it with previous divalent ion-bound TmCorA structures. With Mg 2+ present, this structure shows binding of a hydrated Mg 2+ ion to the periplasmic Gly-Met-Asn (GMN) motif, revealing clues of ion selectivity in this unique channel family. In the absence of Mg 2+ , TmCorA displays an unexpected asymmetric conformation caused by radial and lateral tilts of protomers that leads to bending of the central, pore-lining helix. Molecular dynamics simulations support these movements, including a bell-like deflection. Mass spectrometric analysis confirms that major proteolytic cleavage occurs within a region that is selectively exposed by such a bell-like bending motion. Our results point to a sequential allosteric model of regulation, where intracellular Mg 2+ binding locks TmCorA in a symmetric, transport-incompetent conformation and loss of intracellular Mg 2+ causes an asymmetric, potentially influx-competent conformation of the channel.crystallography | gating | limited proteolysis | pentamer C ompared with other common biological ions (Na + , K + , Ca 2+ , Cl − ), very little is known on a molecular level about the cellular homeostasis of Mg 2+ . As the most abundant intracellular divalent cation, it stabilizes phosphate compounds (DNA, RNA, ATP) and their synthesis, is essential for the function of over 300 enzymes, and is central to photosynthesis in plants (1). In addition to antagonizing Ca 2+ signaling (2), Mg 2+ has recently been implicated as a key second messenger in T-cell activation through the MagT1 Mg 2+ channel (3). The CorA protein is the primary transport system for Mg 2+ in Bacteria and Archaea and is required for bacterial pathogenesis (4, 5). It can functionally substitute for its eukaryotic homologs Alr1 and Mrs2 (6, 7), suggesting that CorA represents an important model system for these eukaryotic Mg 2+ channels. Alr1 is the major Mg 2+ uptake system in the plasma membrane of yeast (8), and Mrs2 is present in the inner mitochondrial membranes of yeast (6), plants (9), and mammals (10). Despite Mrs2 being essential for normal mitochondrial function (11), its expression is a hallmark of embryonic stem cells (12), and Mrs2 overexpression has been linked to a multidrug resistance phenotype in cancer (13,14). Patch-clamp analysis established Mrs2 as a high-conductance (155 pS) Mg 2+ -selective channel (15), and a similar conductivity has been indicated for CorA (16).Three crystal structures of wild-type Thermotoga maritima CorA (TmCorA-WT), obtained in the presence of divalent cations (17-19), revealed a symmetric ho...

show abstract

Mg2+-dependent gating of bacterial MgtE channel underlies Mg2+ homeostasis

Cited by 92 publications

References 37 publications

Structural insights into the mechanisms of Mg ²⁺ uptake, transport, and gating by CorA

Structural insights into the mechanisms of Mg ²⁺ uptake, transport, and gating by CorA

Role of CBS and Bateman Domains in Phosphorylation-Dependent Regulation of a CLC Anion Channel

Structural asymmetry in the magnesium channel CorA points to sequential allosteric regulation

Contact Info

Product

Resources

About

Mg2+-dependent gating of bacterial MgtE channel underlies Mg2+ homeostasis

Cited by 92 publications

References 37 publications

Structural insights into the mechanisms of Mg 2+ uptake, transport, and gating by CorA

Structural insights into the mechanisms of Mg 2+ uptake, transport, and gating by CorA

Role of CBS and Bateman Domains in Phosphorylation-Dependent Regulation of a CLC Anion Channel

Structural asymmetry in the magnesium channel CorA points to sequential allosteric regulation

Contact Info

Product

Resources

About

Structural insights into the mechanisms of Mg ²⁺ uptake, transport, and gating by CorA

Structural insights into the mechanisms of Mg ²⁺ uptake, transport, and gating by CorA