3DWM: Crystal Structure Of Mycobacterium Tuberculosis Cyso, An Antigen

The structure of the protein complex CysM-CysO from a new cysteine biosynthetic pathway found in the H37Rv strain of Mycobacterium tuberculosis has been determined at 1.53 A resolution. CysM (Rv1336) is a PLP-containing beta-replacement enzyme and CysO (Rv1335) is a sulfur carrier protein with a ubiquitin-like fold. CysM catalyzes the replacement of the acetyl group of O-acetylserine by CysO thiocarboxylate to generate a protein-bound cysteine that is released in a subsequent proteolysis reaction. The protein complex in the crystal structure is asymmetric with one CysO protomer binding to one end of a CysM dimer. Additionally, the structures of CysM and CysO were determined individually at 2.8 and 2.7 A resolution, respectively. Sequence alignments with homologues and structural comparisons with CysK, a cysteine synthase that does not utilize a sulfur carrier protein, revealed high conservation of active site residues; however, residues in CysM responsible for CysO binding are not conserved. Comparison of the CysM-CysO binding interface with other sulfur carrier protein complexes revealed a similarity in secondary structural elements that contribute to complex formation in the ThiF-ThiS and MoeB-MoaD systems, despite major differences in overall folds. Comparison of CysM with and without bound CysO revealed conformational changes associated with CysO binding.
PDB ID: 3DWMDownload
MMDB ID: 66948
PDB Deposition Date: 2008/7/22
Updated in MMDB: 2011/10
Experimental Method:
x-ray diffraction
Resolution: 2.69  Å
Source Organism:
Similar Structures:
Biological Unit for 3DWM: monomeric; determined by author and by software (PISA)
Molecular Components in 3DWM
Label Count Molecule
Protein (1 molecule)
9.5 KDA Culture Filtrate Antigen Cfp10a
Molecule annotation
* Click molecule labels to explore molecular sequence information.

Citing MMDB