1. Volume 8, Issue 12, Pages 1299-1308 (December 2000)
Cross-Talk and Ammonia Channeling between Active Centers in the Unexpected Domain Arrangement of Glutamate Synthase 
Claudia Binda, Roberto T. Bossi, Soichi Wakatsuki, Steffi Arzt, Alessandro Coda, Bruno Curti, Maria A. Vanoni, Andrea Mattevi 
Structure 
Volume 8, Issue 12, Pages (December 2000)
DOI: /S (00)

2. Figure 1
Scheme of the Overall Reaction Catalyzed by the α Subunit of A. brasilense GltS
Structure 2000 8, DOI: ( /S (00) )

3. Figure 2
Stereo View of the Experimental Electron-Density Map at 3.0 Å for Residues 1370–1388 which Form the Seventh Helical Turn of the β-Helix Domain
The trace of the Cα atoms is shown as a coil colored in magenta. The map was calculated using coefficients m|Fp|eiαdm, where m is the figure of merit, |Fp| is the observed structure factor amplitude for the native protein, and αdm is the phase value resulting from refinement and extension of the initial MAD phases using solvent flattening and 2-fold averaging. The atomic coordinates are of the final model. The contour level is 1.3 σ. Carbon atoms are in black, oxygen in red, and nitrogen in blue
Structure 2000 8, DOI: ( /S (00) )

4. Figure 3 Overall Structure of GltS α Subunit
(a) Molscript [36] representation of the αGltS monomer. The N-terminal amidotransferase domain is in light blue, the central domain in red, the FMN binding domain in green, and the C-terminal β-helix in magenta. This color scheme will be used throughout the paper. The vertical bar identifies the domain boundaries along the sequence. A dashed line connects residues 1172–1179 and 1194–1202 since the intervening polypeptide segments could not be located in the electron density map.
(b) Stereo drawing of the αGltS dimer viewed along the non-crystallographic 2-fold axis. With respect to Figure 3a, the model has been rotated by ∼90° around the horizontal axis and 30° around the axis perpendicular to the plane of the drawing
Structure 2000 8, DOI: ( /S (00) )

5. Figure 4
Stereo View of the Amidotransferase Active Site with Bound MetS Inhibitor
The drawing shows in ribbon representation the polypeptide segments 210–231 of αGltS (light blue) and 73–90 of L-glutamine phosphoribosylpyrophosphate amidotransferase (light gray). These residues form a loop that covers the active center and adopts a different conformation in αGltS with respect to homologous amidotransferases. The picture was obtained by superimposing the structure of L-glutamine phosphoribosylpyrophosphate amidotransferase (PDB entry 1ECC [4]) onto the amidotransferase domain of αGltS. The orientation is the same as in Figure 3b. Carbon atoms are in black, oxygen in red, nitrogen in blue, and sulfur in green. The inhibitor MetS is colored in dark gray. Atoms within H-bond distance (d<3.2 Å) are connected by dashed lines
Structure 2000 8, DOI: ( /S (00) )

6. Figure 5
Stereo View of the Active Site of the FMN Binding Domain with the Two Cofactors, FMN and 3Fe-4S Cluster, and the Bound 2-Oxoglutarate Substrate
The drawing highlights the position of the active site at the top of the (β/α)8 barrel covered by loops 4 and 6. Met479 is located between the cluster and the flavin ring and belongs to a loop of the central domain. Backbone traces are colored according to domain as in Figure 3a, whereas atoms are as in Figure 4. 2-Oxoglutarate is colored in dark gray. Atoms within H-bond distance (d<3.2 Å) are connected by dashed lines
Structure 2000 8, DOI: ( /S (00) )

7. Figure 6
Structural Homology between the FMN Binding and Central Domains
The secondary structure elements of the core of the two domains are superimposed. Strands and helices of the FMN binding (β/α)8 barrel are numbered sequentially. Colors are as in Figure 3a
Structure 2000 8, DOI: ( /S (00) )

8. Figure 7 Stereo View of the β-Helix of αGltS
The domain is shown in an orientation chosen to highlight the groove on the surface of the domain parallel to the main helical axis
Structure 2000 8, DOI: ( /S (00) )

9. Figure 8 Ammonia Channeling in GltS
(a) Stereo view of the Cα trace of the αGltS subunit with the two cavities that form the ammonia tunnel. The cavities were calculated with the program VOIDOO [35] using a probe radius of 1.4 Å. They are shown in a chicken-wire representation. The bonds connecting the Cα atoms of residues 210–234, of loop 470–520 on the central domain, of loops 4 (residues 933–978) and 6 (1025–1047) on the FMN binding domain are thicker to highlight their position in the structure. Cα traces are colored according to domain as in Figure 3a. The orientation is the same as in Figure 3b. FMN, 3Fe-4S cluster, 2-oxoglutarate, and MetS are in black.
(b) Close-up view of the residues lining the ammonia tunnel involved in signal transduction among redox and active centres. The represented residues are those highlighted in Figure 8a. Atoms within H-bond distance (d<3.2 Å) are connected by dashed lines. 2-Oxoglutarate and MetS are colored in dark gray, whereas all other atoms are colored as in Figure 4
Structure 2000 8, DOI: ( /S (00) )