Studies on uroporphyrinogen decarboxylase fromChlorella kessleri(Trebouxiophyceae, Chlorophyta)

Abstract

Uroporphyrinogen decarboxylase (UroD) (EC 4.1.1.37) is an enzyme from the tetrapyrrole biosynthetic pathway, in which chlorophyll is the main final product in algae. This is the first time that a study on UroD activity has been performed in a green alga (Chlorella). We isolated and partially purified the enzyme from a Chlorella kessleri (Trebouxiophyceae, Chlorophyta) strain (Copahue, Neuquén, Argentina), and describe for the first time some of its properties. In C. kessleri, the decarboxylation of uroporphyrinogen III occurs in two stages, via 7 COOH and then 6 and 5 COOH intermediates, with the decarboxylation of the 7 COOH compound being the rate-limiting step for the reaction. Cultures in the exponential growth phase showed the highest specific activity values. The most suitable conditions to measure UroD activity in C. kessleri were as follows: 0.23-0.3 mg protein/mL, approximately 6-8 micromol/L uroporphyrinogen III, and 20 min incubation time. Gel filtration chromatography and Western blot assays indicated that UroD from C. kessleri is a dimer of approximately 90 kDa formed by species of lower molecular mass, which conserves enzymatic activity.

Effect of a short-term light stress on resistance, signaling, metabolism, and cell division of Ulva prolifera revealed by omics

“…Proteomics data showed that the expression of proteins related to biosynthesis of chlorophyll was upregulated, e.g., uroporphyrinogen decarboxylase (involved in the synthesis of chlorophyll and porphyrin [24], 3.84), heat shock protein 90-5, chloroplastic (the molecular chaperones required for chloroplast biogenesis are critical for chloroplast biogenesis and maintenance,1.59), s1-domaincontaining protein (participates in chloroplast biogenesis,1.74), ABC transporter C family member 1(transport of chlorophyll catabolites, 2.61), ABC transporter C family member 2(transport of chlorophyll catabolites, 1.92); And up-regulated with proteins that slow down the C3 pathway, e.g., pyridoxal 5'phosphate synthase subunit PDX1 (catalyzes the formation of pyridoxal 5'-phosphate from ribose 5phosphate (RBP), glyceraldehyde 3-phosphate (G3P) and ammonia, 2.04).…”

“…Proteomics data showed that the expression of proteins related to protein synthesis was down-regulated, e.g., pre-mRNA-splicing factor ATP-dependent RNA helicase DEAH3 (may be involved in pre-mRNA splicing, 0.37), eukaryotic translation initiation factor 5A-2 (the precise role of eIF-5A in protein biosynthesis is not known but it functions by promoting the formation of the rst peptide bond,0.60), DNA binding helix-turn helix protein (it has the activity of transcription coactivators and participates in the transcription process,0.24), glutamate--cysteine ligase (synthesis of glutathione is involved in interpretation,0.30).photosystem I (PSI) biogenesis, 0.59), polynucleotide-3'-phosphatase ZDP (nicksensing 3'-phosphoesterase involved in a base excision repair pathway required for active DNA demethylation, 0.46). And the expression of proteins involved in photosynthesis were up-regulated, e.g., uroporphyrinogen decarboxylase (involved in the synthesis of chlorophyll and porphyrin [24],3.83).…”