Comparative analysis of two thioredoxins from Schizosaccharomyces pombe

Comparative analysis of two thioredoxins from Schizosaccharomyces pombe

Eukaryotic thioredoxins (TRXs) have been implicated in a wide variety of biochemical and physiological functions. Previously, a genomic DNA and a cDNA encoding thioredoxin were cloned from Schizosaccharomyces pombe. However, C-terminal coding region and downstream region were found to be different, when compared with the two nucleotide sequences. The putative C-terminal region of TRX (called C-type) estimated from the cDNA contains -V-R-L-N-R-S-L, whereas that of TRX (called G-type) predicted from the genomic DNA, contains -A-S-I-K-A-N-L. The plasmid pYJKI which codes for the G-type TRX restored normal growth in the mutant E. coli strain, whereas the plasmid pYM51 which codes for the C-type TRX didn't. The C-type TRX is able to act as a subunit of T7 DNA polymerase, while the G-type TRX is not. Both types of TRX are able to act as a cofactor of methionine sulfoxide reductase and are successfully used for the assembly mechanism of filamentous phages. Due to the differences in the C-terminal amino acid sequences of two S. pombe TRXs, they show some differences in case of growth complementation and T7 phage growth.