Table 2.
Multiple-missense mutations identified in sequenced clones and assessment of location in the 3D homology model compared to single-missense mutants. Sites of single-missense mutant clones are displayed in bold and residues in the putative ligand-binding site that interact with docked norspermidine (nspd) are shown in blue. Short descriptions of the location of each residue in 3D in the double and triple mutants is separated by slashes. ‘Site’ signifies amino acid position. Note: S79N, S79R, L82V, S216G, S216N, R219L, D263N, D263E and N268I are not identical mutations found in single-missense mutants, but are representatives of the same ‘sites’
|
Mutant clone |
Mutations |
Location in the 3D model |
|---|---|---|
|
mut3 |
L75F, S171N |
On two separate helices on two lobes; same surface as single mutants |
|
mut25 |
W8R, Y213N |
Signal peptide – excluded/on loop; same surface as single mutants |
|
mut212 |
N62I, D263N |
On beta-strand; same surface as single mutants/includes single-mutation-site residue that interacts with docked nspd in the closed model |
|
mut233 |
S79G, S216G |
Includes single mutation sites |
|
mut246 |
S79G, S216G |
Includes single mutation sites |
|
mut320 |
V80I, D263E |
On loop; same surface as single mutation site/includes single-mutation-site residue that interacts with docked nspd in the closed model |
|
mut453 |
P117H, S216N |
On helix near hinge region; different location from single mutants/includes single mutation site |
|
mut468 |
S79G, S216G |
Includes single mutation sites |
|
mut486 |
F84V, T149A |
Includes single mutation site/on mobile loop in back of bottom lobe; different location from single mutants |
|
mut558 |
R219C, D236V |
Includes single mutation site/residue that interacts with docked nspd in the closed model |
|
mut629 |
D69V, R219L |
On loop near N68 that moves upon transition from opened to closed conformations/includes single mutation site |
|
mut652 |
N68I, A94T |
Includes single-mutation-site residue in nspd ligand - binding site/on helix at different location from single mutants |
|
mut693 |
N68I, A94T |
Includes single-mutation-site residue in nspd ligand - binding site/on helix at different location from single mutants |
|
mut707 |
S79N, L182H |
Includes single mutation site/on helix at different location from single mutants |
|
mut719 |
M14K, S79G |
Signal peptide-excluded/includes single mutation site |
|
mut731 |
L82V, A108S |
Includes single mutation site/on mobile loop in different location from single mutants |
|
mut844 |
P117H, S216N |
On helix near hinge region; different location from single mutants/includes single mutation site |
|
mut867 |
S79R, N268I |
Includes single mutation sites |
|
mut907 |
H126Y, S216N |
On mobile loop in different location from single mutants/includes single mutation site |
|
mut1202 |
A33D, N115K |
Signal peptide-excluded/on loop near hinge; different location from single mutants |
|
mut1222 |
A33D, N115K |
Signal peptide-excluded/on loop near hinge; different location from single mutants |
|
mut1294 |
S79N, P117S |
Includes single mutation site/on loop near hinge; different location from single mutants |
|
mut1355 |
R112P, D236E |
On mobile loop near hinge region; different location from single mutants/residue that interacts with docked nspd in closed model |
|
mut1384 |
D67N, L341H |
On loop near N68 that moves upon transition from opened to closed conformations/on helix at different location from single mutants |
|
mut1459 |
T174R, A204S |
On helices on one lobe at different locations from single mutants |
|
mut1474 |
L40R, E329V |
Includes single mutation site/on helix near hinge region; different location from single mutants |
|
mut118 |
D170Y, N183H, F283I |
Close to ligand-binding site in closed conformation/on mobile loop near hinge region; different location from single mutants/on same helix as L281 single mutant |
|
mut1104 |
R112H, P177H, L343H |
On mobile loop near hinge region; different location from single mutants/on helices; different location from single mutants |
|
mut1279 |
S79G, I187N, S337L |
Includes single mutation site/on mobile loop near hinge region; different location from single mutants/at end of helix at different location from single mutants |
|
mut1308 |
S216G, K286I, E295V |
Includes single mutation site/on backside of loop and helix away from single mutant sites |
|
mut1423 |
E42G, V102I, E173K |
On loop with D43 single mutant/on loop away from single mutants/residue that interacts with docked nspd in closed model |
|
mut294 |
P83H, K146E, S220N, P311L |
Includes single mutation site/on mobile loop in back; different location from single mutations/on same helix as R219 single mutant/on backside of loop and helix away from single mutant sites |