Open AccessSepiapterin reductases from Chlorobium tepidum and Chlorobium limicola catalyze the synthesis of l ‐threo‐tetrahydrobiopterin from 6‐pyruvoyltetrahydropterin
Author(s) -
Choi Yong Kee,
Jun SiReong,
Cha EunYoung,
Park Jung Soon,
Park Young Shik
Publication year - 2005
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1016/j.femsle.2004.10.044
Subject(s) - tetrahydrobiopterin , biochemistry , peptide sequence , stereochemistry , escherichia coli , chemistry , tetrapyrrole , biology , enzyme , cofactor , gene
The ORF sequences of the gene encoding sepiapterin reductase were cloned from the genomic DNAs of Chlorobium tepidum and Chlorobium limicola , which are known to produce l ‐threo‐ and l ‐erythro‐tetrahydrobiopterin (BH4)‐ N ‐acetylglucosamine, respectively. The deduced amino acid sequence of C. limicola consists of 241 residues, while C. tepidum SR has three residues more at the C‐terminal. The overall protein sequence identity was 87.7%. Both recombinant proteins generated from Escherichia coli were identified to catalyze reduction of diketo compound 6‐pyruvoyltetrahydropterin to l ‐threo‐BH4. This result suggests that C. limicola needs an additional enzyme for l ‐erythro‐BH4 synthesis to yield its glycoside. The catalytic activity of Chlorobium SRs also supports the previously proposed mechanism of two consecutive reductions of C1′ carbonyl group of 6‐pyruvoyltetrahydropterin via isomerization reaction.