TY - JOUR
T1 - Cadmium tolerance plasticity in Rhizobium leguminosarum bv. viciae
T2 - glutathione as a detoxifying agent
AU - Figueira, Etelvina Maria De Almeida Paula
AU - Lima, Ana Isabel Gusmão
AU - Pereira, Sofia Isabel Almeida
PY - 2005/1
Y1 - 2005/1
N2 - Rhizobium leguminosarum bv. viciae strains expressing different degrees of tolerance to metal stress were used in this work to study the basic mechanisms underlying heavy metal tolerance. We used various parameters to evaluate this response. The strains' growth responses under different Cd2+ concentrations were determined and we reported variation in Cd2+ tolerance. Total soluble protein content decreased drastically, revealing the toxic effects that intracellular Cd2+ imposes on cellular metabolism, but this decrease in protein content was particularly evident in sensitive and moderately tolerant strains. Tolerant strains presented the highest intracellular and wall-bound Cd2+ concentrations. Cd2+ induced increases in the expression of some specific proteins, which were identical in all tolerant strains. Glutathione levels remained unaltered in the sensitive strain and increased significantly in tolerant and moderately tolerant strains, suggesting the importance of glutathione in coping with metal stress. This work suggests that efflux mechanisms may not be the only system responsible for dealing with heavy metal tolerance. A clear correlation between glutathione levels and Cd2+ tolerance is reported, thus adding a novel aspect in bacteria protection against heavy metal deleterious effects.
AB - Rhizobium leguminosarum bv. viciae strains expressing different degrees of tolerance to metal stress were used in this work to study the basic mechanisms underlying heavy metal tolerance. We used various parameters to evaluate this response. The strains' growth responses under different Cd2+ concentrations were determined and we reported variation in Cd2+ tolerance. Total soluble protein content decreased drastically, revealing the toxic effects that intracellular Cd2+ imposes on cellular metabolism, but this decrease in protein content was particularly evident in sensitive and moderately tolerant strains. Tolerant strains presented the highest intracellular and wall-bound Cd2+ concentrations. Cd2+ induced increases in the expression of some specific proteins, which were identical in all tolerant strains. Glutathione levels remained unaltered in the sensitive strain and increased significantly in tolerant and moderately tolerant strains, suggesting the importance of glutathione in coping with metal stress. This work suggests that efflux mechanisms may not be the only system responsible for dealing with heavy metal tolerance. A clear correlation between glutathione levels and Cd2+ tolerance is reported, thus adding a novel aspect in bacteria protection against heavy metal deleterious effects.
KW - Glutathione
KW - Heavy metal
KW - Protein expression
KW - Rhizobia
KW - Thiol quantification
UR - http://www.scopus.com/inward/record.url?scp=19044392202&partnerID=8YFLogxK
U2 - 10.1139/w04-101
DO - 10.1139/w04-101
M3 - Article
C2 - 15782229
AN - SCOPUS:19044392202
SN - 0008-4166
VL - 51
SP - 7
EP - 14
JO - Canadian Journal of Microbiology
JF - Canadian Journal of Microbiology
IS - 1
ER -