Trinary
Biochemical Metal
Processor PMBT

First capture of extracellular Hg²⁺, transfer to MerT via thiol binding.

Specific channel transporting Hg²⁺ from periplasm to cytoplasm.

MerC: alternative Hg²⁺ entry. MerE: specialized in CH₃Hg⁺ and phenylmercury import.

ArsB antiporter (H⁺-driven) + ArsA ATPase for enhanced arsenite expulsion. Primary detoxification route.

Transfers As(III) to ArsA with high efficiency, increasing pump affinity by ~3× and reducing Km.

CXXC-motif metallochaperone shuttling Cu⁺ to CopA P-type ATPase. Prevents free Cu⁺ toxicity.

RND-type transenvelope complex exporting Cu⁺/Ag⁺ directly to extracellular space. Bypasses periplasm.

CadA: P-type ATPase for Cd²⁺ efflux. CadC: sensor that de-represses cadA upon Cd²⁺ detection.

Tripartite RND efflux system providing high-level Zn²⁺/Cd²⁺/Co²⁺ resistance via proton-driven transenvelope export.

CDF-family antiporter providing basal Zn²⁺ efflux. His-rich cytoplasmic loop buffers Zn²⁺ before export.

CHR superfamily chromate-specific antiporter. Only known CrO₄²⁻-specific efflux pump, driven by proton motive force.

PbrD sequesters Pb²⁺ intracellularly and delivers it to PbrA P-type ATPase for ATP-driven efflux.

RND-type tripartite system from C. metallidurans. Primary Co²⁺/Ni²⁺ export route via proton antiport.

NiCoT-family transporter providing secondary Co²⁺/Ni²⁺ efflux. Regulated by RcnR repressor.

Integral membrane protein conferring tellurite resistance. May facilitate TeO₃²⁻ export or intracellular reduction to Te⁰.

RND-type tripartite efflux system from A. xylosoxidans. Optimized for Ni²⁺ export with Co²⁺ as secondary substrate.

Silver-specific P-type ATPase pumping Ag⁺ to periplasm. Receives Ag⁺ from SilF periplasmic chaperone.

RND complex ejecting periplasmic Ag⁺ to extracellular space. Works in tandem with SilP for full Ag⁺ detoxification.

SilE: Ag⁺-binding protein (His-rich) capturing free Ag⁺. SilF: metallochaperone shuttling Ag⁺ from SilE to SilCBA/SilP.

Molybdoenzyme complex reducing SeO₄²⁻ to SeO₃²⁻. First step of selenium detoxification pathway in T. selenatis.

Thioredoxin-dependent reductase converting SeO₃²⁻ to Se⁰ red nanoparticles. Visual readout of Se trinary state.

Cross-reactive ArsB antiporter exporting Sb(III) via H⁺ antiport. Same transporter as arsenite efflux with similar affinity.

Transmembrane electron conduit (MtrC-MtrA-MtrB) enabling extracellular UO₂²⁺ reduction by Shewanella. Decaheme cytochromes relay electrons.

Decaheme cytochromes on cell surface (Shewanella OmcA) or conductive pili (Geobacter OmcS). Direct contact with UO₂²⁺ for reduction.

High-affinity Mn²⁺ import controlled by MntR. MntC binds periplasmic Mn²⁺, MntB is the permease, MntA hydrolyzes ATP.

NRAMP-family H⁺-coupled Mn²⁺ importer. Secondary import route complementing MntABC. Also imports Fe²⁺.

Master switch protein from D. radiodurans that activates DNA repair, ROS detoxification, and metal resistance genes simultaneously. Enhances processor reliability under radiation stress.

Key enzyme from Desulfovibrio producing H₂S which precipitates metals as insoluble sulfides (HgS, CdS, PbS, ZnS, CuS). Alternative metal immobilization pathway.

Blue copper protein from A. ferrooxidans mediating electron transfer during Fe²⁺/Cu⁺ oxidation at extreme pH (1.5–2.0). Enables acidic-route metal processing for PMBT input preparation.

Redundant Cr(VI) reductases from E. cloacae. NemA (N-ethylmaleimide reductase) and YieF (xenobiotic reductase) both reduce chromate to Cr(III). Provides fault-tolerant Cr processing.

ABC-type tungstate importer. TupA periplasmic binding protein (Kd ~0.5 nM) discriminates WO₄²⁻ from MoO₄²⁻. TupB permease + TupC ATPase. Primary W acquisition system.

Alternative tungstate importer found in Pyrobaculum. WtpA has picomolar Kd for WO₄²⁻ — the highest known affinity for any metalloanion. Enables W acquisition from trace environmental tungstate.

Vanadium-binding protein secreted by P. isachenkovii. Sequesters reduced vanadyl V(IV) outside the cell, preventing re-oxidation and re-entry. Unique “export-and-trap” detoxification strategy.

Inner membrane components of the ModABC molybdate transporter. ModB provides the transmembrane channel; ModC hydrolyzes ATP. Expression repressed by ModE when Mo is sufficient.

TolC homolog in H. pylori. Forms the outer-membrane exit channel of the RND tripartite efflux pump (with HP0606/AcrB + HP0607/AcrA). Exports Bi³⁺ and multiple antibiotics.

P-type ATPase importing K⁺ at low concentrations. Tl⁺ enters via K⁺ mimicry (ionic radius 1.49 Å vs 1.38 Å). KdpB catalytic subunit, KdpA channel, KdpC auxiliary, KdpF stabilizer. Primary Tl⁺ uptake route exploited for trit loading.

Mechanosensitive K⁺ efflux system co-exporting Tl⁺. Gated by GSH/GSSG ratio — electrophile stress opens the channel. Provides Tl⁺ detoxification by rapid cytoplasmic clearance coupled to K⁺ homeostasis.

Primary Cu⁺ efflux ATPase. Receives Cu⁺ from CopZ chaperone and exports to periplasm. Two Cu-binding CXXC domains in N-terminal region. Essential for Cu trinary state control — calibrates cytoplasmic Cu⁺ for trit assignment.

High-affinity MoO₄²⁻ binding protein (Kd ~20 nM). Delivers molybdate to ModBC permease for import. Discriminates MoO₄²⁻ from SO₄²⁻ by oxyanion size. Part of ModABC transporter regulated by ModE repressor.

High-affinity Ni²⁺ importer for urease/hydrogenase metallocenter assembly. NikA periplasmic Ni²⁺-binding protein, NikB/C permease, NikD/E ATPase. Regulated by NikR repressor. Loads Ni²⁺ for trit encoding.

His-rich metallochaperone delivering Ni²⁺ to urease active site. Binds 5–6 Ni²⁺ per dimer via C-terminal His-tail. Works with UreG (GTPase) and UreF/UreH assembly complex. Prevents free Ni²⁺ toxicity during biosensor loading.

Low-affinity phosphate importer that co-transports H₂VO₄⁻ (vanadate) due to structural mimicry of HPO₄²⁻. Primary route for V(V) cellular uptake. Metal:phosphate selectivity ~1:50, but sufficient for vanadate sensing at µM concentrations.

AcrAB homolog in H. pylori (HP0606/HP0607). AcrB-like component (BirB) provides the proton-driven substrate translocation; AcrA-like (BirA) bridges to HP0605/TolC. Complete tripartite system for Bi³⁺ export across both membranes.

High-affinity Zn²⁺ importer. ZnuA periplasmic Zn²⁺-binding protein (His-rich loop), ZnuB permease, ZnuC ATPase. Regulated by Zur repressor. Ensures adequate Zn²⁺ loading for trit-state initialization.

PbrB: undecaprenyl pyrophosphate phosphatase generating Pi for Pb²⁺ precipitation as Pb₅(PO₄)₃OH (insoluble). PbrC: signal peptidase maturing PbrA. Together with PbrD/PbrA, complete the Pb sequestration-efflux-precipitation cycle.

TehA: potassium efflux channel with tellurite transport activity. TehB: SAM-dependent methyltransferase possibly methylating tellurite. Together with TerC, provides dual-pathway TeO₃²⁻ detoxification via efflux and methylation.

ACR3 family permease for trivalent arsenical and antimonial efflux. Broader substrate range than ArsB — also exports methylated arsenicals (MAs(III), DMAs(III)). Provides parallel Sb(III) detoxification pathway distinct from ArsB.

Non-selective divalent cation channel importing Co²⁺ (and Mg²⁺, Ni²⁺). Pentameric funnel with selectivity filter. Primary route for Co²⁺ trit loading at physiological concentrations. Inhibited by high [Mg²⁺].