Caesium transport in the cyanobacterium Anabaena variabilis: Kinetics and evidence for uptake via ammonium transport system(s)

Simon V. Avery; Geoffrey A. Codd; Geoffrey M. Gadd

doi:10.1016/0378-1097(92)90438-T

Caesium transport in the cyanobacterium Anabaena variabilis: Kinetics and evidence for uptake via ammonium transport system(s)

Simon V. Avery, Geoffrey A. Codd, Geoffrey M. Gadd (Lead / Corresponding author)

University of Dundee

Research output: Contribution to journal › Article › peer-review

19 Citations (Scopus)

Abstract

Analysis of caesium uptake over a range of external Cs⁺ concentrations revealed that uptake was determined by a single transport system [K_m approx. 0.25 mM; V_max approx. 220 nmol Cs⁺ h^-1 (10⁹ cells)^-1] in the cyanobacterium Anabaena variabilis. Linear inhibition of Cs⁺ uptake in the presence of elevated external concentrations of NH₄⁺ (added as chloride) resulted in an increase in the K_m and a decrease in the V_max suggesting that NH₄⁺ was a competitive/non-competitive inhibitor of Cs⁺ uptake. Cs⁺ uptake was markedly dependent on the nitrogen source supplied during growth of A. variabilis; maximal uptake was observed in nitrogen-fixing cells. Lowest levels of Cs⁺ uptake were observed in a mutant strain of A. variabilis which was deficient in NH₄⁺ transport. These results suggest that Cs⁺ and NH₄⁺ share a common transport mechanism in A. variabilis.

Original language	English
Pages (from-to)	253-258
Number of pages	6
Journal	FEMS Microbiology Letters
Volume	95
Issue number	2-3
DOIs	https://doi.org/10.1016/0378-1097(92)90438-T
Publication status	Published - 1 Aug 1992

Keywords

Ammonium uptake
Anabaena variabilis
Caesium uptake
Cyanobacterium
Transport kinetics

ASJC Scopus subject areas

Microbiology
Molecular Biology
Genetics

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10.1016/0378-1097(92)90438-T

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title = "Caesium transport in the cyanobacterium Anabaena variabilis: Kinetics and evidence for uptake via ammonium transport system(s)",

abstract = "Analysis of caesium uptake over a range of external Cs+ concentrations revealed that uptake was determined by a single transport system [Km approx. 0.25 mM; Vmax approx. 220 nmol Cs+ h-1 (109 cells)-1] in the cyanobacterium Anabaena variabilis. Linear inhibition of Cs+ uptake in the presence of elevated external concentrations of NH4+ (added as chloride) resulted in an increase in the Km and a decrease in the Vmax suggesting that NH4+ was a competitive/non-competitive inhibitor of Cs+ uptake. Cs+ uptake was markedly dependent on the nitrogen source supplied during growth of A. variabilis; maximal uptake was observed in nitrogen-fixing cells. Lowest levels of Cs+ uptake were observed in a mutant strain of A. variabilis which was deficient in NH4+ transport. These results suggest that Cs+ and NH4+ share a common transport mechanism in A. variabilis.",

keywords = "Ammonium uptake, Anabaena variabilis, Caesium uptake, Cyanobacterium, Transport kinetics",

author = "Avery, {Simon V.} and Codd, {Geoffrey A.} and Gadd, {Geoffrey M.}",

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T2 - Kinetics and evidence for uptake via ammonium transport system(s)

AU - Avery, Simon V.

AU - Codd, Geoffrey A.

AU - Gadd, Geoffrey M.

PY - 1992/8/1

Y1 - 1992/8/1

N2 - Analysis of caesium uptake over a range of external Cs+ concentrations revealed that uptake was determined by a single transport system [Km approx. 0.25 mM; Vmax approx. 220 nmol Cs+ h-1 (109 cells)-1] in the cyanobacterium Anabaena variabilis. Linear inhibition of Cs+ uptake in the presence of elevated external concentrations of NH4+ (added as chloride) resulted in an increase in the Km and a decrease in the Vmax suggesting that NH4+ was a competitive/non-competitive inhibitor of Cs+ uptake. Cs+ uptake was markedly dependent on the nitrogen source supplied during growth of A. variabilis; maximal uptake was observed in nitrogen-fixing cells. Lowest levels of Cs+ uptake were observed in a mutant strain of A. variabilis which was deficient in NH4+ transport. These results suggest that Cs+ and NH4+ share a common transport mechanism in A. variabilis.

AB - Analysis of caesium uptake over a range of external Cs+ concentrations revealed that uptake was determined by a single transport system [Km approx. 0.25 mM; Vmax approx. 220 nmol Cs+ h-1 (109 cells)-1] in the cyanobacterium Anabaena variabilis. Linear inhibition of Cs+ uptake in the presence of elevated external concentrations of NH4+ (added as chloride) resulted in an increase in the Km and a decrease in the Vmax suggesting that NH4+ was a competitive/non-competitive inhibitor of Cs+ uptake. Cs+ uptake was markedly dependent on the nitrogen source supplied during growth of A. variabilis; maximal uptake was observed in nitrogen-fixing cells. Lowest levels of Cs+ uptake were observed in a mutant strain of A. variabilis which was deficient in NH4+ transport. These results suggest that Cs+ and NH4+ share a common transport mechanism in A. variabilis.

KW - Ammonium uptake

KW - Anabaena variabilis

KW - Caesium uptake

KW - Cyanobacterium

KW - Transport kinetics

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EP - 258

JO - FEMS Microbiology Letters

JF - FEMS Microbiology Letters

IS - 2-3

ER -

Caesium transport in the cyanobacterium Anabaena variabilis: Kinetics and evidence for uptake via ammonium transport system(s)

Abstract

Keywords

ASJC Scopus subject areas

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