Crystal structure of the catalytic domain of a human thioredoxin-like protein.
Thioredoxin is a ubiquitous dithiol oxidoreductase found in many organisms and involved in numerous biochemical processes. Human thioredoxin-like protein (hTRXL) is differentially expressed at different development stages of human fetal cerebrum and belongs to an expanding family of thioredoxins. We have solved the crystal structure of the recombinant N-terminal catalytic domain (hTRXL-N) of hTRXL in its oxidized form at 2.2-A resolution. Although this domain shares a similar three-dimensional structure with human thioredoxin (hTRX), a unique feature of hTRXL-N is the large number of positively charged residues distributed around the active site, which has been implicated in substrate specificity. Furthermore, the hTRXL-N crystal structure is monomeric while hTRX is dimeric in its four crystal structures (reduced, oxidized, C73S and C32S/C35S mutants) reported to date. As dimerization is the key regulatory factor in hTRX, the positive charge and lack of dimer formation of hTRXL-N suggest that it could interact with the acidic amino-acid rich C-terminal region, thereby suggesting a novel regulation mechanism.
Jin
Jian
J
Laboratory of Structural Biology and the MOE Laboratory of Protein Science, School of Life Science & Engineering, Tsinghua University, Beijing, China.
Chen
Xuehui
X
Zhou
Yan
Y
Bartlam
Mark
M
Guo
Qing
Q
Liu
Yiwei
Y
Sun
Yixin
Y
Gao
Yu
Y
Ye
Sheng
S
Li
Guangtao
G
Rao
Zihe
Z
Qiang
Boqin
B
Yuan
Jiangang
J
D020134:Catalytic Domain; D006801:Humans; D008958:Models, Molecular; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013329:Structure-Activity Relationship; D013379:Substrate Specificity; D013879:Thioredoxins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
D011994:Recombinant Proteins; C504766:TXNL1 protein, human; D013879:Thioredoxins