Further characterization and amino acid sequence of m-type thioredoxins from spinach chloroplasts

Abstract

The complete primary structure of m-type thioredoxin from spinach chloroplasts has been sequenced by conventional sequencing including fragmentation, Edman degradation and carboxypeptidase digestion. As already reported [Tsugita, A., Maeda, K. & Schurmann, P. (1983) Biochem. Biophys. Res. Commun. 11.5, 1-71 these thioredoxins contain the same active-site sequence as thioredoxins from other sources. Based on the amino acid sequence thioredoxin mc contains 103 residues, has a relative molecular mass of 11 425 and a molar absorption coefficient at 280 nm of 19300 M-' cm-'. The spinach thioredoxin mc has an overall homology of 44% with the thioredoxin from Escherichia coli mainly due to differences in the N-terminal and C-terminal regions.Thioredoxins are ubiquitous low-molecular-mass proteins with an oxidation-reduction active disulfide made up of two half-cystines. Thioredoxin was first isolated and purified from Escherichiu coli [l] where the protein can function as a hydrogen donor for the ribonucleotide reductase [2]. Subsequently thioredoxins were found in various organisms and shown to participate in a variety of oxidation-reduction reactions of the cellular metabolism [3]. In addition thioredoxin from E. coli constitutes a subunit of the phage T7-induced DNA polymerase [4].In green plant cells thioredoxins have been recognized as part of a light-dependent regulatory system in photosynthesis capable of turning on and off the activity of key chloroplast enzymes [5].Relatively few thioredoxins have been studied extensively and only three complete amino acid sequences have been reported so far, namely for the thioredoxins from E. coli [6], bacteriophage T4 [7] and Corynebacteriurn nephridii [8]. The three-dimensional structures of the first two thioredoxins have been solved by X-ray crystallography [9, 101. The proteins show great similarities in their overall structures despite the absence of significant sequence homologies. For the thioredoxins from yeast [ll], Anabaena [12, 131, calf liver [3] and rat liver [14] the amino acid sequence around the active site has been determined. Except for the thioredoxin from phage

Cloning of the HSP70 gene from Halobacterium marismortui: relatedness of archaebacterial HSP70 to its eubacterial homologs and a model for the evolution of the HSP70 gene

“…6). It is suggested that the evolution of the ancestral HSP70 began with an ancient 130-to 160-amino-acid domain corresponding to its N-terminal quadrant and probably related to the m-type thioredoxin (31) (Fig. 6, the ancestral HSP70 version, represented by those present in archaebacteria and gram-positive bacteria (stage III).…”

“…The sequence similarity between MreB and other HSP70s was comparable to the above percentage (Table 2). However, when alignment was carried out with other HSP70 sequences which do not contain the deletion in the N-terminal quadrant, then a large gap in the MreB sequence in the In addition to MreB, a somewhat lower but significant homology of HSP70 with the m-type thioredoxin from spinach chloroplast was also noted (31). Interestingly, this latter protein, which has only 104 amino acid residues, showed maximum similarity to the first quadrant of the HSP70 sequence from gram-positive bacteria.…”

Thioredoxins: structure and function in plant cells

“…The chloroplastic sequences of thioredoxin/and m from higher plants are preceded by a transit peptide without any clear homologies even when they belong to very similar proteins. The N-terminal sequence of the mature proteins is not always easy to determine because of blocked N-termini except in the case of thioredoxin m (Maeda et al, 1986;Decottignies et al, 1990). The first third of the protein (amino-terminal part to the active site) is generally the least conserved part, the C-terminal part being much more similar in all the groups considered.…”

A novel thioredoxin‐like protein located in the chloroplast is induced by water deficit in Solanum tuberosum L. plants

“…Plant and E. coli thioredoxin sequence names correspond to SWISS-PROT identification names. THII_TOBAC: tobacco thioredoxin h 2 (Brugidou et al, 1993); THIH_TOBAC: tobacco thioredoxin h 1 (Brugidou et al, 1993); THIF_SPIOL: spinach thioredoxin f (Kamo et al, 1989); THIM_SPIOL: spinach thioredoxin m (Maeda et al, 1986); THIO_ECOLI: E. coli thioredoxin (Hö ö g et al, 1985). (c) Sequence alignment of CDSP 32 N-terminal 121 residues and C-terminal 122 residues.…”