PDBsum entry: 1vjj

Transferase

PDB id: 1vjj

Contents

Protein chains

675 a.a. *

Ligands

GDP ×2

Metals

_CL ×2

_CA ×6

_MG ×2

Waters ×898

* Residue conservation analysis

Obsolete entry

PDB id:

1vjj

Name:

Transferase

Title:

Structural basis for the coordinated regulation of transglut by guanine nucleotides and calcium/magnesium

Structure:

Protein-glutamine glutamyltransferase e. Chain: a, b. Synonym: tgase e, tge, tge, transglutaminase 3. Engineered: yes. Mutation: yes

Source:

Homo sapiens. Human. Organism_taxid: 9606. Tissue: foreskin. Gene: tgm3. Expressed in: spodoptera frugiperda. Expression_system_taxid: 7108. Expression_system_cell_line: sf9. (Invitrogen), bac-n-blue (invitrogen).

Resolution:

1.90Å R-factor: 0.205 R-free: 0.236

Authors:

B.Ahvazi

Key ref:

B.Ahvazi et al. (2004). Structural basis for the coordinated regulation of transglutaminase 3 by guanine nucleotides and calcium/magnesium. J Biol Chem, 279, 7180-7192. PubMed id: 14645372 DOI: 10.1074/jbc.M312310200

Date:

24-Feb-04 Release date: 02-Mar-04

Protein chains

Q08188  (TGM3_HUMAN) -  Protein-glutamine gamma-glutamyltransferase E

Seq: 693 a.a.

Struc: 675 a.a.*

* PDB and UniProt seqs differ at 3 residue positions (black crosses)

Enzyme reactions

• Enzyme class: E.C.2.3.2.13 - Protein-glutamine gamma-glutamyltransferase.
• Reaction: Protein glutamine + alkylamine = protein N₅-alkylglutamine + NH₃
• Cofactor: Calcium

Molecule diagrams generated from .mol files obtained from the KEGG ftp site

reference

DOI no: 10.1074/jbc.M312310200

J Biol Chem 279:7180-7192 (2004)

PubMed id: 14645372

Structural basis for the coordinated regulation of transglutaminase 3 by guanine nucleotides and calcium/magnesium.

B.Ahvazi, K.M.Boeshans, W.Idler, U.Baxa, P.M.Steinert, F.Rastinejad.

ABSTRACT

Transglutaminase 3 (TGase 3) is a member of a family of Ca2+-dependent enzymes that catalyze covalent cross-linking reactions between proteins or peptides. TGase 3 isoform is widely expressed and is important for effective epithelial barrier formation in the assembly of the cell envelope. Among the nine TGase enzyme isoforms known in the human genome, only TGase 2 is known to bind and hydrolyze GTP to GDP; binding GTP inhibits its transamidation activity but allows it to function in signal transduction. Here we present biochemical and crystallographic evidence for the direct binding of GTP/GDP to the active TGase 3 enzyme, and we show that the TGase 3 enzyme undergoes a GTPase cycle. The crystal structures of active TGase 3 with guanosine 5'-O-(thiotriphosphate) (GTPgammaS) and GDP were determined to 2.1 and 1.9 A resolution, respectively. These studies reveal for the first time the reciprocal actions of Ca2+ and GTP with respect to TGase 3 activity. GTPgammaS binding is coordinated with the replacement of a bound Ca2+ with Mg2+ and conformational rearrangements that together close a central channel to the active site. Hydrolysis of GTP to GDP results in two stable conformations, resembling both the GTP state and the non-nucleotide bound state, the latter of which allows substrate access to the active site.

Selected figure(s)

Figure 6.
FIG. 6. The electrostatic surface potential comparison of the TGase 3·GTP S/GDP complexes. The front and back view represent images rotated 180° with respect to each other to show the channel in the active TGase 3 form. The acidic and basic regions are colored red and blue, respectively. The electrostatic potentials, including Ca^2+ and Mg2+ ions, have been mapped onto the surface plan from -15 kT (deep red) to +15 kT (deep blue). The open channel is clearly evident in B when Ca^2+ ion is present at site 3 and closed when Ca^2+ metal is replaced by Mg2+ ion in TGase 3·GDP complex. A, the "back" side of the enzyme has a deep cavity; the "front" side remains closed in TGase 3·GTP S complex.

Figure 8.
FIG. 8. A, the view of modeled interactions of SQQ*VT (from loricrin) for the Gln* substrate and KTKQK* (from small proline-rich protein 1) as the Lys* substrate with GDP molecules that is shown in ball-and-stick. The side chains for the active site residues and Cys272, His330, and Asp353 are shown as ball-and-stick. B, the amino acid sequence alignment of TGases family is shown around the guanine nucleotide-binding site pocket. The amino acids highlighted in red are acidic, blue are basic, yellow are nonpolar, and green are polar residues. Arrows indicate the position of the Arg/Phe residues that stack over the guanine ring in TGase 2 and TGase 3 structures, respectively. The other arrows represent two basic residues that are essential for stabilizing the transition states for GTP hydrolysis.

The above figures are reprinted by permission from the ASBMB: J Biol Chem (2004, 279, 7180-7192) copyright 2004.

Figures were selected by the author.