| SKS6 (SKU5-Similar) is a member of a highly homologous gene family of nineteen in Arabidopsis thaliana . It is predicted to be a multicopper oxidase, an enzyme requiring copper ions for proper folding and activity. Laccases, ascorbate oxidases and ferroxidases are the three main kinds of multicopper oxidases. SKS6 and other family members are closely related to these enzymes in structure, but their function is unknown. The gene has been cloned and the protein expressed as a fusion protein with glutathione - S transferase moiety in the N-terminus. It did not show laccase activity when purified. Based on the expression pattern of the promoter-GUS fusion, SKS6 is expressed in hydathodes, guard cells, mature root cortex, apical meristem, ovules, floral meristem and in abscission zones of seeds and siliques. Several alleles of SKS6 are described that contain insertions in the gene. T-DNA allele SALK_36979 shows a phenotype in cotyledon vasculature and morphology, where it exhibits a decreased percentage of full vascular loops and a smaller petit chapeau (little hat). Young seedlings treated with plant hormones abscisic acid (ABA), indole-3 acetic acid (IAA), 2,4-Dichlorophenoxyacetic acid (2,4-D) and aminocyclopropane-1-carboxylate (ACC) showed upregulated expression of SKS6 in root tips and root epidermis. The SKS6 gene product may play an important role in the reshaping of cell wall structure during plant growth and response to stress, as well as in keeping general cellular integrity. |
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