Purification and characterization of a novel glutathione transferase from Serratia marcescens.
Four forms of glutathione transferase were resolved from the cytosol of Serratia marcescens CIP 6755 by GSH-affinity chromatography followed by isoelectric focusing. The major isoenzyme, named Sm-GST-7.3, is composed of two subunits each with a molecular mass of 22 kDa and has an isoelectric point at pH 7.3. Sm-GST-7.3, appears to be distinct from Pm-GST-6.0, previously characterized from Proteus mirabilis AF 2924 as indicated by its substrate specificity, immunological reactivity, subunit molecular mass as well as by its N-terminal amino acid sequence. None of the antisera raised against a number of human, rat and mouse GSTs cross-reacted with Sm-GST-7.3 indicating major structural differences between them and bacterial GST. This is further supported by the fact that the N-terminal sequence of Sm-GST-7.3 also differs significantly from the known sequences of mammalian GSTs of alpha, mu and pi classes. In addition, comparison with the known N-terminal amino acid sequences of helminth, plant and insect GSTs demonstrate that the latter enzymes are distantly related (less than 25% identity) to the Sm-GST-7.3. Immunoblotting experiments performed with antisera raised against Sm-GST-7.3 indicate that a GST immunologically identical to Sm-GST-7.3 is present in a number of other bacterial strains. All together the results obtained suggest that Sm-GST-7.3 is distinct from any known GST, including microbial and mammalian GSTs.
Di Ilio
C
C
Instituti di Scienze Biochimiche e Medicina Sperimentale, Facoltà di Medicina, Università G. D'Annunzio, Chieti, Italy.
Aceto
A
A
Piccolomini
R
R
Allocati
N
N
Faraone
A
A
Bucciarelli
T
T
Barra
D
D
Federici
G
G
D000595:Amino Acid Sequence; D015153:Blotting, Western; D002846:Chromatography, Affinity; D003429:Cross Reactions; D004591:Electrophoresis, Polyacrylamide Gel; D005982:Glutathione Transferase / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D007525:Isoelectric Focusing; D008969:Molecular Sequence Data; D012706:Serratia marcescens / Q000201:enzymology*; D013379:Substrate Specificity
D005982:Glutathione Transferase