Molecular characterization of glyoxalase-I from a higher plant; upregulation by stress.
A cDNA, GLX1, encoding glyoxalase-I was isolated by differential screening of salt-induced genes in tomato. Glyoxalases-I and -II are ubiquitous enzymes whose functions are not clearly understood. They may serve to detoxify methylglyoxal produced from triosephosphates in all cells. The protein encoded by GLX1 shared 49.4% and 58.5% identity with glyoxalase-I isolated from bacteria and human, respectively. Furthermore, yeast cells expressing GLX1 showed a glyoxalase-I specific activity 20-fold higher than non-transformed cells. Both GLX1 mRNA and glyoxalase-I polypeptide levels increased 2- to 3-fold in roots, stems and leaves of plants treated with either NaCl, mannitol, or abscisic acid. Immunohistochemical localization indicated that glyoxalase-I was expressed in all cell types, with preferential accumulation in phloem sieve elements. This expression pattern was not appreciably altered by salt-stress. We suggest that the increased expression of glyoxalase-I may be linked to a higher demand for ATP generation and to enhanced glycolysis in salt-stressed plants.
Espartero
J
J
Instituto de Recursos Naturales y Agrobiología, C.S.I.C., Sevilla, Spain.
Sánchez-Aguayo
I
I
Pardo
J M
JM
D000595:Amino Acid Sequence; D001419:Bacteria / Q000201:enzymology; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D006801:Humans; D007150:Immunohistochemistry; D007791:Lactoylglutathione Lyase / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics; D018551:Solanum lycopersicum / Q000201:enzymology*; D008969:Molecular Sequence Data; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry; D012441:Saccharomyces cerevisiae; D017386:Sequence Homology, Amino Acid; D013312:Stress, Physiological
D018076:DNA, Complementary; D011994:Recombinant Proteins; D007791:Lactoylglutathione Lyase