Nickel uptake in Bradyrhizobium japonicum

Journal Article · Wed Apr 01 04:00:00 EST 1987 · J. Bacteriol.; (United States)

OSTI ID:6077746

Stults, L W; Mallick, S; Maier, R J

Free-living Bradyrhizobium japonicum grown heterotrophically with 1 ..mu..M /sup 63/Ni/sup 2 +/ accumulated label. Strain SR470, a Hup/sup c/ mutant, accumulated almost 10-fold more /sup 63/Ni/sup 2 +/ on a per-cell basis than did strain SR, the wild type. Nongrowing cells were also able to accumulate nickel over a 2-h period, with the Hup/sup c/ mutant strain SR470 again accumulating significantly more /sup 63/Ni/sup 2 +/ than strain SR. These results suggest that this mutant is constitutive for nickel uptake as well as for hydrogenase expression. The uptake process was relatively specific for nickel; only Cu/sup 2 +/ and Zn/sup 2 +/ (10 ..mu..M) were found to appreciably inhibit the uptake of 1 ..mu..M Ni, while a 10-fold excess of Mg/sup 2 +/, Co/sup 2 +/, Fe/sup 3 +/, or Mn/sup 2 +/ did not affect Ni/sup 2 +/ uptake. The lack of inhibition by Mg/sup 2 +/ indicates that nickel is not transported by a magnesium uptake system. Nickel uptake was also inhibited by cold and slightly by the ionophores nigericin and carbonyl cyanide m-chlorophenylhydrazone. The cytochrome c oxidase inhibitors azide, cyanide, and hydroxylamine did not inhibit Ni/sup 2 +/ uptake, even at concentrations (of cyanide and hydroxylamine) that inhibited O/sub 2/ uptake. The addition of oxidizable substrates such as succinate or gluconate did not increase nickel uptake, even though they increased respiratory activity. Nickel uptake showed a pH dependence with an optimum at 6.0. Most (approximately 85%) of the /sup 63/Ni/sup 2 +/ taken up in 1 min by strain SR470 was not exchangeable with cold nickel.

• Research Organization: Johns Hopkins Univ., Baltimore, MD
• OSTI ID: 6077746
• Journal Information: J. Bacteriol.; (United States), Journal Name: J. Bacteriol.; (United States) Vol. 169:4; ISSN JOBAA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
BACTERIA
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOLOGICAL PATHWAYS
CATIONS
CHARGED PARTICLES
EVEN-ODD NUCLEI
INTERMEDIATE MASS NUCLEI
IONS
ISOTOPE APPLICATIONS
ISOTOPES
METABOLISM
MICROORGANISMS
MUTANTS
NICKEL 63
NICKEL COMPOUNDS
NICKEL ISOTOPES
NUCLEI
RADIOISOTOPES
RHIZOBIUM
TRACER TECHNIQUES
TRANSITION ELEMENT COMPOUNDS
UPTAKE
YEARS LIVING RADIOISOTOPES