Biology subjects

Nurbekova, Z.

Publications and source records attributed to Nurbekova, Z..

3 recordsLinked to original sources

bioRxiv2023

AAO2 impairment improves aldehyde detoxification by AAO3 in Arabidopsis leaves exposed to UVC or Rose Bengal.

Among the three active aldehyde oxidases in Arabidopsis thaliana leaves (AAO1-3), AAO3, which catalyzes the oxidation of abscisic-aldehyde to abscisic-acid, was shown recently to function as a reactive aldehyde detoxifier. Notably, aao2KO mutants exhibited less senescence symptoms and lower aldehyde accumulation, such as acrolein, benzaldehyde, and HNE than in wild-type leaves exposed to UV-C or Rose-Bengal. The effect of the absence of AAO2 expression on aldehyde detoxification by AAO3 and/or AAO1 was studied by comparing the response of wild-type plants to the response of aao1Single mutant, aao2KO mutants and single mutants of aao3Ss. Notably, aao3Ss exhibited similar aldehyde accumulation and chlorophyll content to aao2KO treated with UV-C or Rose-Bengal. In contrast, wild-type and aao1S exhibited higher aldehyde accumulation that resulted in lower remaining chlorophyll than in aao2KO leaves, indicating that the absence of active AAO2 enhanced AAO3 detoxification activity in aao2KO mutants. In support of this notion, employing abscisic-aldehyde as a specific substrate marker for AAO3 activity revealed enhanced AAO3 activity in aao2KO and aao3Ss leaves compared to wild-type treated with UV-C or Rose Bengal. The similar abscisic acid level accumulated in leaves of unstressed or stressed genotypes indicates that aldehyde detoxification by AAO3 is the cause for better stress resistance in aao2KO mutants. Employing the sulfuration process (known to activate aldehyde oxidases) in wild-type, aao2KO, and molybdenum-cofactor sulfurase (aba3-1) mutant plants revealed that the active AAO2 in WT employs sulfuration processes essential for AAO3 activity level, resulting in the lower AAO3 activity in WT than AAO3 activity in aao2KO.

plant biology↗

bioRxiv2021

Ureides are similarly accumulated in response to UV-C irradiation and wound but differently remobilized during recovery in Arabidopsis leaves.

To examine a role of purine degraded metabolites in response to wounding or UV-C stress, the Arabidopsis wild-type and Atxdh1 KO mutants, defective in xanthine dehydrogenase1 (XDH1), were exposed to wounding and UV-C irradiation stress. In Atxdh1 mutant, wounding or UV-C stresses resulted in lower fresh-weight, increased senescence symptoms and higher tissue cell death rate compared to Wild-type. Additionally, Wild-type exhibited lower levels of oxidative stress indicators; reactive oxygen species and malondialdehyde than Atxdh1 mutant leaves. Notably, purine degradation transcripts and proteins were orchestrated to lead to enhanced ureide levels in Wild-type leaves 24 h after applying UV-C or wound stress. Yet, different remobilization of the accumulated ureides was noticed 72 h after stresses application. In plants treated with UV-C the allantoin level was highest in young leaves, whereas in wounded plants it was lowest in the young leaves, accumulated mainly in the middle and wounded leaves. The results indicate that in UV-C treated Wild-type, during the recovery period from stress, ureides are remobilized from the lower older leaves to support young leaf growth. In contrast, after wounding, the ureides are remobilized to the young leaves, yet more to the middle wounded leaves, to function as antioxidants and/or healing agents. HighlightUV-C and wound triggers purine degradation in old and damaged leaves to increase ureides accumulation in stress dependent rate. Impairment in purine degradation results in premature senescence in leaves.

plant biology↗

bioRxiv2020

Impairment in O-acetylserine-(thiol) lyase A and B, but not C, confers higher selenate sensitivity and uncovers role for A, B and C as L-Cys and L-SeCys desulfhydrases in Arabidopsis

The role of the cytosolic O-acetylserine-(thiol) lyase A (OASTLA), chloroplastic OASTLB and mitochondrion OASTLC in plant resistance/sensitivity to selenate was studied in Arabidopsis plants. Impairment in OASTLA and B resulted in reduced biomass, chlorophyll and soluble protein levels compared with impaired OASTL C and Wild-Type treated with selenate. The lower organic-Se and protein-Se levels followed by decreased organic-S, S in proteins and total glutathione in oastlA and oastlB compared to Wild-Type and oastlC are indicative that Se accumulation is not the main cause for the stress symptoms, but rather the interference of Se with the S-reduction pathway. The increase in sulfite oxidase, adenosine 5'-phosphosulfate reductase, sulfite reductase and OASTL activity levels, followed by enhanced sulfite and sulfide, indicate a futile anabolic S-starvation response to selenate-induced organic-S catabolism in oastlA and oastlB compared to Wild-Type and oastlC. Additionally, the catabolic pathway of L-cysteine degradation was enhanced by selenate, and similar to L-cysteine producing activity, oastlA and B exhibited a significant decrease in L-cysteine desulfhydrase (DES) activity, compared with WT, indicating a major role of OASTLs in L-cysteine degradation. This notion was further evidenced by sulfide dependent DES in-gel activity, immunoblotting, immunoprecipitation with specific antibodies and identification of unique peptides in activity bands generated by OASTLA, B and C. Similar responses of the OASTLs in Seleno-Cysteine degradation was demonstrated in selenate stressed plants. Notably, no L-cysteine and L-Seleno-Cysteine DES activity bands but those related to OASTLs were evident. These results indicate the significance of OASTLs in degrading L-cysteine and L-SelenoCysteine in Arabidopsis. SummaryThe cytosolic OASTLA and chloroplastic OASTLB have significantly higher desulfhydrase activity rates than the cytosolic DES1 and are able to degrade L-Cys and L-SeCys to sulfide and selenide, respectively in Arabidopsis.

biochemistry↗