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Table 1 List of transport systems reported to be involved in tellurite- (abbreviated as Te) and selenite- (abbreviated as Se) uptake by cells of various bacterial species (see text for further details and below for symbols and abbreviations used)

From: Tellurite and Selenite: how can these two oxyanions be chemically different yet so similar in the way they are transformed to their metal forms by bacteria?

Oxyanions

Transport systems

Bacterial species

Method used to define the transport system

Results observed

Refs.

Tellurite

PitA (low-affinity Pi transporter)

E.coli

pitA gene deletion

ΔpitA mutant: increased tolerance to Te

[66]

 

ActP (acetate permeases ActP1, ActP2)

R.capsulatus

actP gene deletion

ΔactP mutant: increased resistance to Te

[64, 65]

 

ActP2

R.capsulatus, E.coli

Expression of ActP2 from R. capsulatus into E.coli

E.coli actP2::lacZ mutant: 4-times higher Te-uptake than w.t

[72]

 

ActP

E.coli

actP gene deletion

#Active at short-times of exposure to Te

[63]

 

PitA + PitB (low-affinity + putative Pi transporters)

E.coli

pitA + pitB gene deletion

#Active at long-times of exposure to Te

[63]

 

PstA, PstD

(high-affinity Pi transporter)

L.lactis

§Insertions into pstA + pstD genes

Strong increase in resistance to Te

[71]

Selenite

Pi transporters

E.coli

Addition of Pi to growth medium

Large decrease of Se uptake in Pi amended cultures

[92]

 

* Undefined sulphate permease

E.coli

Kinetic analysis of sulphate, selenate and Se uptake

Se and selenate compete for a common sulphate carrier

[79]

 

PitA (low-affinity Pi transporter)

E.coli

pitA gene deletion

ΔpitA mutant: large decrease of Se-reduction rate

[92]

 

PstA (high-affinity Pi transporter)

E.coli

pstA gene deletion

ΔpstA mutant: decrease of Se-reduction rate

[92]

 

SmoK protein (ABC transporter like)

R.sphaeroides

smoK gene deletion

ΔsmoK mutant: tenfold increase of MIC for Se

[46]

 

Pi transporters

C.reinhardtii

Addition of Pi to growth medium

Decrease of Se- uptake in Pi amended cultures

[94]

 

Mono-carboxylates transporters

C.reinhardtii

Addition of lactate to growth medium

Increase of Se-uptake in lactate amended cultures

[94]

  1. *Carrier subsequently identified by others (see [96]) as Sulfate-Thiosulfate SulT permease; #, ‘short- and long-times of exposures’ stand for 5 and 30 min, respectively [63]; §, ‘insertions’ stands for ‘insertional random mutagenesis’ [71]; Se, selenite; Te, tellurite; MIC, Minimum Inhibitory Concentration; Pi, phosphate; PstA, phosphate transport ATP-ase [71]; PastD, phosphate transport permease [71]; ROS, Reactive Oxygen Species; w.t., wild type; Bacterial species: E. coli, Escherichia coli; L. lactis, Lactococcus lactis; R. capsulatus, Rhodobacter capsulatus; R. sphaeroides, Rhodobacter sphaeroides; Rsp. rubrum, Rhodospirillum rubrum; C. reinhardtii, Chlamidomonas reinhardtii