Occurrence of two different glutamate dehydrogenase activities in the halophilic bacterium Salinibacter ruber

Salinibacter ruber, an extremely halophilic member of the domain Bacteria, has two different cytoplasmic glutamate dehydrogenase activities, marked as GDHI and GDHII. GDHI showed a strong dependence on high salt concentrations for stability, but not for activity, displaying maximal activity in the a...

Full description

Saved in:
Bibliographic Details
Published in:FEMS microbiology letters 2003-09, Vol.226 (1), p.181-186
Main Authors: Maria-José Bonete, Pérez-Pomares, Francisco, Díaz, Susana, Ferrer, Juan, Oren, Aharon
Format: Article
Language:English
Subjects:
Adenosine diphosphate
Adenosine triphosphate
Amination
Amino acids
Bacteria
Deamination
Dehydrogenase
Dehydrogenases
Dependence
Glutamate dehydrogenase
Histidine
Ketoglutaric acid
Leucine
Microbiology
Nucleotides
pH effects
Phenylalanine
Potassium chloride
Salinibacter ruber
Salts
Sodium chloride
Stability
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Salinibacter ruber, an extremely halophilic member of the domain Bacteria, has two different cytoplasmic glutamate dehydrogenase activities, marked as GDHI and GDHII. GDHI showed a strong dependence on high salt concentrations for stability, but not for activity, displaying maximal activity in the absence of salts. GDHII depended on high salt concentrations for both activity and stability. It catalyzed amination of 2-oxoglutarate with optimal activity in 3 M KCl at pH 8. No activating effect was found when NaCl was replaced by KCl. Only GDHII displayed activity in the deamination reaction of glutamate with an optimal pH of 9.5. Both enzymes were activated by certain amino acids (l-leucine, l-histidine, l-phenylalanine) and by nucleotides such as ADP or ATP. A low-molecular-mass cytoplasmic fraction was found to be a highly effective activator of GDHII in the presence of high NaCl concentrations.
ISSN:0378-1097
1574-6968
DOI:10.1016/S0378-10970300592-5