PDBsum entry 2vps

Ligase

PDB id: 2vps

Contents

Protein chain

603 a.a. *

Metals

_CL ×5

_BR ×2

Waters ×45

* Residue conservation analysis

PDB id:

2vps

Name:

Ligase

Title:

Structure of the bifunctional leishmania major trypanothione synthetase-amidase

Structure:

Trypanothione synthetase. Chain: a. Engineered: yes

Source:

Leishmania major. Organism_taxid: 5664. Strain: friedlin. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

2.75Å R-factor: 0.207 R-free: 0.250

Authors:

P.K.Fyfe,S.L.Oza,A.H.Fairlamb,W.N.Hunter

Key ref:

P.K.Fyfe et al. (2008). Leishmania trypanothione synthetase-amidase structure reveals a basis for regulation of conflicting synthetic and hydrolytic activities. J Biol Chem, 283, 17672-17680. PubMed id: 18420578 DOI: 10.1074/jbc.M801850200

Date:

04-Mar-08 Release date: 06-May-08

Protein chain

Q711P7  (Q711P7_LEIMA) -  Putative trypanothione synthetase from Leishmania major

Seq: 652 a.a.

Struc: 603 a.a.

Enzyme reactions

• Enzyme class: E.C.6.3.1.9 - trypanothione synthase.
• Reaction:
  1. spermidine + glutathione + ATP = glutathionylspermidine + ADP + phosphate + H⁺
  2. glutathionylspermidine + glutathione + ATP = trypanothione + ADP + phosphate + H⁺
• Cofactor: Mg(2+)

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

reference

DOI no: 10.1074/jbc.M801850200

J Biol Chem 283:17672-17680 (2008)

PubMed id: 18420578

Leishmania trypanothione synthetase-amidase structure reveals a basis for regulation of conflicting synthetic and hydrolytic activities.

P.K.Fyfe, S.L.Oza, A.H.Fairlamb, W.N.Hunter.

ABSTRACT

The bifunctional trypanothione synthetase-amidase catalyzes biosynthesis and hydrolysis of the glutathione-spermidine adduct trypanothione, the principal intracellular thiol-redox metabolite in parasitic trypanosomatids. These parasites are unique with regard to their reliance on trypanothione to determine intracellular thiol-redox balance in defense against oxidative and chemical stress and to regulate polyamine levels. Enzymes involved in trypanothione biosynthesis provide essential biological activities, and those absent from humans or for which orthologues are sufficiently distinct are attractive targets to underpin anti-parasitic drug discovery. The structure of Leishmania major trypanothione synthetase-amidase, determined in three crystal forms, reveals two catalytic domains. The N-terminal domain, a cysteine, histidine-dependent amidohydrolase/peptidase amidase, is a papain-like cysteine protease, and the C-terminal synthetase domain displays an ATP-grasp family fold common to C:N ligases. Modeling of substrates into each active site provides insight into the specificity and reactivity of this unusual enzyme, which is able to catalyze four reactions. The domain orientation is distinct from that observed in a related bacterial glutathionylspermidine synthetase. In trypanothione synthetase-amidase, the interactions formed by the C terminus, binding in and restricting access to the amidase active site, suggest that the balance of ligation and hydrolytic activity is directly influenced by the alignment of the domains with respect to each other and implicate conformational changes with amidase activity. The potential inhibitory role of the C terminus provides a mechanism to control relative levels of the critical metabolites, trypanothione, glutathionylspermidine, and spermidine in Leishmania.

Selected figure(s)

Figure 1.
FIGURE 1. Ligation and hydrolytic reactions catalyzed by trypanothione synthetase-amidase. Trypanothione is produced by stepwise ligation of glutathione with spermidine (reaction I), then glutathionylspermidine (reaction II). Hydrolysis of trypanothione (reaction III) then glutathionylspermidine (reaction IV) is performed by the N-terminal amidase domain.

Figure 2.
FIGURE 2. Secondary, tertiary, and domain structure of LmTSA. a, the fold. Red and black stars mark amidase and synthetase active sites, respectively. Selected elements of secondary structure are labeled. 1 is blue, and the β-barrel is red. b, the subdomain structure of the ATP-grasp synthetase domain viewed orthogonal to a. Subdomain A is colored orange, subdomain B is blue, and subdomain C is purple. A model of ADP (black sticks, based on structural comparisons) is included.

The above figures are reprinted by permission from the ASBMB: J Biol Chem (2008, 283, 17672-17680) copyright 2008.

Figures were selected by the author.