PDBsum entry 1xn4

Structural genomics, unknown function

PDB id: 1xn4

Contents

Protein chain

191 a.a. *

* Residue conservation analysis

PDB id:

1xn4

Name:

Structural genomics, unknown function

Title:

Putative mar1 ribonuclease from leishmania major

Structure:

Ribonuclease mar1. Chain: a. Engineered: yes

Source:

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

Biol. unit:

Tetramer (from PDB file)

Resolution:

3.80Å R-factor: 0.313 R-free: 0.312

Authors:

J.Caruthers,E.A.Merritt,Structural Genomics Of Pathogenic Protozoa Consortium (Sgpp)

Key ref:

J.Caruthers et al. (2005). Crystal structures and proposed structural/functional classification of three protozoan proteins from the isochorismatase superfamily. Protein Sci, 14, 2887-2894. PubMed id: 16199669

Date:

04-Oct-04 Release date: 12-Oct-04

Protein chain

Q4QGT7  (Q4QGT7_LEIMA) -  Ribonuclease mar1 from Leishmania major

Seq: 192 a.a.

Struc: 191 a.a.

Protein Sci 14:2887-2894 (2005)

PubMed id: 16199669

Crystal structures and proposed structural/functional classification of three protozoan proteins from the isochorismatase superfamily.

J.Caruthers, F.Zucker, E.Worthey, P.J.Myler, F.Buckner, W.Van Voorhuis, C.Mehlin, E.Boni, T.Feist, J.Luft, S.Gulde, A.Lauricella, O.Kaluzhniy, L.Anderson, I.Le Trong, M.A.Holmes, T.Earnest, M.Soltis, K.O.Hodgson, W.G.Hol, E.A.Merritt.

ABSTRACT

We have determined the crystal structures of three homologous proteins from the pathogenic protozoans Leishmania donovani, Leishmania major, and Trypanosoma cruzi. We propose that these proteins represent a new subfamily within the isochorismatase superfamily (CDD classification cd004310). Their overall fold and key active site residues are structurally homologous both to the biochemically well-characterized N-carbamoylsarcosine-amidohydrolase, a cysteine hydrolase, and to the phenazine biosynthesis protein PHZD (isochorismase), an aspartyl hydrolase. All three proteins are annotated as mitochondrial-associated ribonuclease Mar1, based on a previous characterization of the homologous protein from L. tarentolae. This would constitute a new enzymatic activity for this structural superfamily, but this is not strongly supported by the observed structures. In these protozoan proteins, the extended active site is formed by inter-subunit association within a tetramer, which implies a distinct evolutionary history and substrate specificity from the previously characterized members of the isochorismatase superfamily. The characterization of the active site is supported crystallographically by the presence of an unidentified ligand bound at the active site cysteine of the T. cruzi structure.