Ammonium and methylammonium transport in Rhodobacter sphaeroides

Marcia L Cordts; Jane Gibson

doi:10.1128/jb.169.4.1632-1638.1987

Back

Ammonium and methylammonium transport in Rhodobacter sphaeroides

Journal article

Open access

Peer reviewed

Ammonium and methylammonium transport in Rhodobacter sphaeroides

Marcia L Cordts and Jane Gibson

Journal of bacteriology, Vol.169(4), pp.1632-1638

1987

DOI: 10.1128/jb.169.4.1632-1638.1987

PMCID: PMC211992

PMID: 2881920

Files and links (1)

url

https://doi.org/10.1128/jb.169.4.1632-1638.1987View

Published (Version of record) Open Access

Abstract

Rhodobacter sphaeroides maintained intracellular ammonium pools of 1.1 to 2.6 mM during growth in several fixed nitrogen sources as well as during diazotrophic growth. Addition of 0.15 mM NH4+ to washed, nitrogen-free cell suspensions was followed by linear uptake of NH4+ from the medium and transient formation of intracellular pools of 0.9 to 1.5 mM NH4+. Transport of NH4+ was shown to be independent of assimilation by glutamine synthetase because intracellular pools of over 1 mM represented NH4+ concentration gradients of at least 100-fold across the cytoplasmic membrane. Ammonium pools of over 1 mM were also found in non-growing cell suspensions in nitrogen-free medium after glutamine synthetase was inhibited with methionine sulfoximine. In NH4+-free cell suspensions, methylammonium (14CH3NH3+) was taken up rapidly, and intracellular concentrations of 0.4 to 0.5 mM were maintained. The 14CH3NH3+ pool was not affected by methionine sulfoximine. Unlike NH4+ uptake, 14CH3NH3+ uptake in nitrogen-free cell suspensions was repressed by growth in NH4+. These results suggest that R. sphaeroides may produce an NH4+-specific transport system in addition to the NH4+/14CH3NH3+ transporter. This second transporter is able to produce normal-size NH4+ pools but has very little affinity for 14CH3NH3+ and is not repressed by growth in high concentrations of NH4+.

Bacteriology

Microbiology

Fundamental and applied biological sciences. Psychology

Biological and medical sciences

Permeability, membrane transport, intracellular transport

Details

Title: Subtitle: Ammonium and methylammonium transport in Rhodobacter sphaeroides
Creators: Marcia L Cordts - Cornell univ., div. biological sci., Ithaca NY 14853, United States
Jane Gibson - Cornell univ., div. biological sci., Ithaca NY 14853, United States
Resource Type: Journal article
Publication Details: Journal of bacteriology, Vol.169(4), pp.1632-1638
DOI: 10.1128/jb.169.4.1632-1638.1987
PMID: 2881920
PMCID: PMC211992
NLM abbreviation: J Bacteriol
ISSN: 0021-9193
eISSN: 1098-5530
Publisher: American Society for Microbiology
Language: English
Date published: 1987
Academic Unit: Microbiology and Immunology
Record Identifier: 9984083250502771

Metrics

21 Record Views

24 Times Cited - Web of Science