TY - JOUR
T1 - Structural and Functional Characterization of an Ancient Bacterial Transglutaminase Sheds Light on the Minimal Requirements for Protein Cross-Linking
AU - Fernandes, Catarina G.
AU - Plácido, Diana
AU - Lousa, Diana
AU - Alves Brito, Jose Artur
AU - Isidro, Anabela
AU - Soares, Cláudio M.
AU - Pohl, Jan
AU - Carrondo, Maria A.
AU - Frazao, Margarida Archer
AU - Henriques, Adriano Jose
PY - 2015/9/22
Y1 - 2015/9/22
N2 - Transglutaminases are best known for their ability to catalyze protein cross-linking reactions that impart chemical and physical resilience to cellular structures. Here, we report the crystal structure and characterization of Tgl, a transglutaminase from the bacterium Bacillus subtilis. Tgl is produced during sporulation and cross-links the surface of the highly resilient spore. Tgl-like proteins are found only in spore-forming bacteria of the Bacillus and Clostridia classes, indicating an ancient origin. Tgl is a single-domain protein, produced in active form, and the smallest transglutaminase characterized to date. We show that Tgl is structurally similar to bacterial cell wall endopeptidases and has an NlpC/P60 catalytic core, thought to represent the ancestral unit of the cysteine protease fold. We show that Tgl functions through a unique partially redundant catalytic dyad formed by Cys116 and Glu187 or Glu115. Strikingly, the catalytic Cys is insulated within a hydrophobic tunnel that traverses the molecule from side to side. The lack of similarity of Tgl to other transglutaminases together with its small size suggests that an NlpC/P60 catalytic core and insulation of the active site during catalysis may be essential requirements for protein cross-linking.
AB - Transglutaminases are best known for their ability to catalyze protein cross-linking reactions that impart chemical and physical resilience to cellular structures. Here, we report the crystal structure and characterization of Tgl, a transglutaminase from the bacterium Bacillus subtilis. Tgl is produced during sporulation and cross-links the surface of the highly resilient spore. Tgl-like proteins are found only in spore-forming bacteria of the Bacillus and Clostridia classes, indicating an ancient origin. Tgl is a single-domain protein, produced in active form, and the smallest transglutaminase characterized to date. We show that Tgl is structurally similar to bacterial cell wall endopeptidases and has an NlpC/P60 catalytic core, thought to represent the ancestral unit of the cysteine protease fold. We show that Tgl functions through a unique partially redundant catalytic dyad formed by Cys116 and Glu187 or Glu115. Strikingly, the catalytic Cys is insulated within a hydrophobic tunnel that traverses the molecule from side to side. The lack of similarity of Tgl to other transglutaminases together with its small size suggests that an NlpC/P60 catalytic core and insulation of the active site during catalysis may be essential requirements for protein cross-linking.
UR - http://www.scopus.com/inward/record.url?scp=84942100927&partnerID=8YFLogxK
U2 - 10.1021/acs.biochem.5b00661
DO - 10.1021/acs.biochem.5b00661
M3 - Article
C2 - 26322858
AN - SCOPUS:84942100927
VL - 54
SP - 5723
EP - 5734
JO - Biochemistry
JF - Biochemistry
SN - 0006-2960
IS - 37
ER -