Academia.eduAcademia.edu

Figure 4 – uploaded by Santosh C M Kumar

See full PDFdownloadDownload figure
Figure 4. Model for the regulation of oligomerization in Mycobacterium tuberculosis GroEL1 mediated by phosphorylation. Upon synthesis, M. tuberculosis GroEL1 monomer might follow two pathways of oligomeriza tion. The monomers either assemble into a dimer or a heptamer. The dimer might act as a storage form or migh be involved in nucleoid formation. Function of the heptameric form is unknown. The signal for the probable con version of the dimeric form into heptameric form is yet to be discerned (shown with a question mark). However the signal for conversion of single-ring heptamer to double-ring tetradecamer is mediated by phosphorylation o1 serine residue(s). The tetradecameric GroEL is supposed to be the active form of the chaperonin.

Figure 4 Model for the regulation of oligomerization in Mycobacterium tuberculosis GroEL1 mediated by phosphorylation. Upon synthesis, M. tuberculosis GroEL1 monomer might follow two pathways of oligomeriza tion. The monomers either assemble into a dimer or a heptamer. The dimer might act as a storage form or migh be involved in nucleoid formation. Function of the heptameric form is unknown. The signal for the probable con version of the dimeric form into heptameric form is yet to be discerned (shown with a question mark). However the signal for conversion of single-ring heptamer to double-ring tetradecamer is mediated by phosphorylation o1 serine residue(s). The tetradecameric GroEL is supposed to be the active form of the chaperonin.

Related Figures (3)

Figure 1. The architecture of Escherichia coli GroEL. a, Crystallographic models of E. coli GroEL and GroEL—GroES complex. Individual domains in one subunit of GroEL are indicated. Api, Apical domain; Int, Intermediate domain; Equ, Equatorial domain. GroES acting as a lid binds to GroEL asymmetrically, at the cis GroEL ring, wherein the substrate polypeptides are encapsulated. The other open ring is termed as the trans ring. Illustrations have been generated using Pymol 0.99, molecular visualization soft- ware from DeLano Scientific LLC, USA. Coordinates for the molecules were obtained from the structures deposited in the Protein Data Bank (PDB) with the ID: 1OEL for GroEL and 1AON for the GroEL-GroES complex structures. b, Crystallographic models of GroEL monomers depicting the domain motions upon ATP binding. GroEL in the substrate-bound form assumes a constricted conformation, positioning the substrates at the opening of the cavity. Upon ATP-binding, rotational movements in the intermediate domain and thereby upward movement of the apical domain result in extended conformation of the molecule. This releases the substrate into the cavity and exposes the helices H and L for GroES binding. Coordinates for the extended and constrained GroEL monomer were obtained from PDB: 1 AON chain A and chain H, respectively.
Figure 1. The architecture of Escherichia coli GroEL. a, Crystallographic models of E. coli GroEL and GroEL—GroES complex. Individual domains in one subunit of GroEL are indicated. Api, Apical domain; Int, Intermediate domain; Equ, Equatorial domain. GroES acting as a lid binds to GroEL asymmetrically, at the cis GroEL ring, wherein the substrate polypeptides are encapsulated. The other open ring is termed as the trans ring. Illustrations have been generated using Pymol 0.99, molecular visualization soft- ware from DeLano Scientific LLC, USA. Coordinates for the molecules were obtained from the structures deposited in the Protein Data Bank (PDB) with the ID: 1OEL for GroEL and 1AON for the GroEL-GroES complex structures. b, Crystallographic models of GroEL monomers depicting the domain motions upon ATP binding. GroEL in the substrate-bound form assumes a constricted conformation, positioning the substrates at the opening of the cavity. Upon ATP-binding, rotational movements in the intermediate domain and thereby upward movement of the apical domain result in extended conformation of the molecule. This releases the substrate into the cavity and exposes the helices H and L for GroES binding. Coordinates for the extended and constrained GroEL monomer were obtained from PDB: 1 AON chain A and chain H, respectively.
Figure 2. Examples of molecular promiscuity. a, Structural comparison of ligand-binding grooves on MHC class I and CD1 molecules. MHC class I molecules present foreign polypeptides to T-cells, whereas the CD1 receptor is implicated in presenting lipids to specific T-cells. Crystallo- graphic models of the polypeptide bound to MHC class I molecule and the lipid moiety bound to CD1 receptor are presented in orange and white respectively. The coordinates for the MHC class I complex and CD1 complex were obtained from PDB: 1HSA and 2AKR respectively. b, Janus chaper- ones in prokaryotic ribosome: Crystallographic models of 50S ribosomal subunit showing the Janus chaperones L15, L16, L18 and L19, as indicated. c, Unstructured nature of the indicated individual chaperones presented in ribbon diagrams. The 23S rRNA is shown in yellow-orange and the 5S rRNA in cyan. Coordinates for the 50S ribosomal subunit and the individual chaperones were obtained from the RCSB protein databank ID: 3E1B.
Figure 2. Examples of molecular promiscuity. a, Structural comparison of ligand-binding grooves on MHC class I and CD1 molecules. MHC class I molecules present foreign polypeptides to T-cells, whereas the CD1 receptor is implicated in presenting lipids to specific T-cells. Crystallo- graphic models of the polypeptide bound to MHC class I molecule and the lipid moiety bound to CD1 receptor are presented in orange and white respectively. The coordinates for the MHC class I complex and CD1 complex were obtained from PDB: 1HSA and 2AKR respectively. b, Janus chaper- ones in prokaryotic ribosome: Crystallographic models of 50S ribosomal subunit showing the Janus chaperones L15, L16, L18 and L19, as indicated. c, Unstructured nature of the indicated individual chaperones presented in ribbon diagrams. The 23S rRNA is shown in yellow-orange and the 5S rRNA in cyan. Coordinates for the 50S ribosomal subunit and the individual chaperones were obtained from the RCSB protein databank ID: 3E1B.
Figure 3. Aconitase as an example of moonlighting. Aconitase is a mitochondrial enzyme involved in catalysing the conversion of citrate to iso- citrate in the citric acid cycle”. In response to iron depletion in the cell, the protein assumes a new conformation and converts its function to iron responsive element (IRE) binding protein. Aconitase in complex with citrate (1C96), isocitrate (1BOJ) and IRE element (2IPY) is presented. The conformational change in complex with IRE is apparent.
Figure 3. Aconitase as an example of moonlighting. Aconitase is a mitochondrial enzyme involved in catalysing the conversion of citrate to iso- citrate in the citric acid cycle”. In response to iron depletion in the cell, the protein assumes a new conformation and converts its function to iron responsive element (IRE) binding protein. Aconitase in complex with citrate (1C96), isocitrate (1BOJ) and IRE element (2IPY) is presented. The conformational change in complex with IRE is apparent.
Related topics:
Heat shock protein, protein foldingGene DuplicationStudies on heat shock proteins
580 California St., Suite 400
San Francisco, CA, 94104
© 2025 Academia. All rights reserved