Arabidopsis thaliana Contains Both Ni2+ and Zn2+ Dependent Glyoxalase I Enzymes and Ectopic Expression of the Latter Contributes More towards Abiotic Stress Tolerance in E. coli

Abstract

The glyoxalase pathway is ubiquitously found in all the organisms ranging from prokaryotes to eukaryotes. It acts as a major pathway for detoxification of methylglyoxal (MG), which deleteriously affects the biological system in stress conditions. The first important enzyme of this system is Glyoxalase I (GLYI). It is a metalloenzyme which requires divalent metal ions for its activity. This divalent metal ion can be either Zn2+ as found in most of eukaryotes or Ni2+ as seen in prokaryotes. In the present study, we have found three active GLYI enzymes (AtGLYI2, AtGLYI3 and AtGLYI6) belonging to different metal activation classes coexisting in Arabidopsis thaliana. These enzymes have been found to efficiently complement the GLYI yeast mutants. These three enzymes have been characterized in terms of their activity, metal dependency, kinetic parameters and their role in conferring tolerance to multiple abiotic stresses in E. coli and yeast. AtGLYI2 was found to be Zn2+ dependent whereas AtGLYI3 and AtGLYI6 were Ni2+ dependent. Enzyme activity of Zn2+ dependent enzyme, AtGLYI2, was observed to be exceptionally high (~250–670 fold) as compared to Ni2+ dependent enzymes, AtGLYI3 and AtGLYI6. The activity of these GLYI enzymes correlated well to their role in stress tolerance. Heterologous expression of these enzymes in E. coli led to better tolerance against various stress conditions. This is the first report of a higher eukaryotic species having multiple active GLYI enzymes belonging to different metal activation classes.

From methylglyoxal to pyruvate: a genome-wide study for the identification of glyoxalases and D-lactate dehydrogenases in Sorghum bicolor

“…Four SbGLYI proteins namely, SbGLYI-7, SbGLYI-10, SbGLYI-11 and SbGLYI-14, were found to be Ni 2+ -dependent showing greater homology to the previously characterised Ni 2+dependent GLYI proteins from rice and Arabidopsis [42,43] and having a similar domain length, of approximately 120 aa. Similarly, only one GLYI protein namely, SbGLYI-8 was found to be Zn 2+ -dependent, having a domain length of 140 aa, much like rice OsGLYI-8 [44] and Arabidopsis AtGLYI-2 [43,45] proteins. Interestingly, SbGLYI-8 possessed two spliced forms coding for almost similar length proteins (214 and 227 aa long), and both were predicted to be similarly localised in the mitochondria and/or chloroplast.…”

“…The metal specificity of SbGLYI proteins was predicted based on their domain sequence and length [40,41]. Four SbGLYI proteins namely, SbGLYI-7, SbGLYI-10, SbGLYI-11 and SbGLYI-14, were found to be Ni 2+ -dependent showing greater homology to the previously characterised Ni 2+dependent GLYI proteins from rice and Arabidopsis [42,43] and having a similar domain length, of approximately 120 aa. Similarly, only one GLYI protein namely, SbGLYI-8 was found to be Zn 2+ -dependent, having a domain length of 140 aa, much like rice OsGLYI-8 [44] and Arabidopsis AtGLYI-2 [43,45] proteins.…”

A nuclear‐localized rice glyoxalase I enzyme, OsGLYI‐8, functions in the detoxification of methylglyoxal in the nucleus

“…The decline was more severe (about 13.5‐fold) in the cytoplasmic fraction, where three AtGLYI‐2 isoforms were found to be localized, as compared with the nuclear fraction which showed a two‐fold decline in GLYI activity (Figure i,j). The GLYI activity in the atglyI‐2 plants did not change significantly in response to salt treatment (Figure i,j), thereby suggesting that AtGLYI‐2 is involved in maintaining increased GLYI activity in plants under saline conditions, as its loss fails to enhance the otherwise observed increase in GLYI activity under salinity stress (Jain et al ., ).…”

Genome-wide analysis of glyoxalase-like gene families in grape (Vitis vinifera L.) and their expression profiling in response to downy mildew infection

“…However, further study revealed that only three Arabidopsis thaliana genes (AtGLYI2, AtGLYI3 and AtGLYI6) and two rice genes (OsGLYI8 and OsGLYI11.2) were functional and contained all the binding sites required for glyoxalase activity. In addition, the activity of AtGLYI2 was dependent on Zn 2+ , while the activities of AtGLYI3, AtGLYI6 and OsGLYI11.2 were dependent on Ni 2+ [11][12][13]. Specifically, OsGLYI-8 did not show any strict requirement for a metal ion for its activity [14].…”