Journal:Acta Cryst F:S2053230X19004618
Novel T9 loop interaction of Filamenting Temperature-sensitive mutant Z from Mycobacterium tuberculosisE. O. Lazo, J. Jakoncic, S. RoyChowdhury, D. Awasthi, I. Ojima [1] Molecular Tour Asymmetric unit contains 6 protomers that form a dimer of trimers (5v68). Protomers A and C shown in blue, protomer B shown in gray, protomers D and F shown in red, protomer E shown in cyan, GDP are represented by orange spheres, and PO4 by green spheres. Trimer ABC superimposed onto DEF. Same color scheme as in previous scene. Comparison of other MtbFtsZ structures with trimer ABC from 5v68 reveals that protomers A and B superimposed well but the conformation of protomer C is vastly different. Structure 5V68 superimposed onto 4KWE. Nucleotide for both is GDP. Color scheme is as follows, 5v68 blue, 4kwe yellow, nucleotides orange spheres, Glu231 green spheres, phosphate red spheres. Click here to see animation of this scene. The trimer ABC from 5v68 is to a curved MtbFtsZ protofilament (PDB 4kwe). Based on an r.m.s.d. of 1.2Å between protomers AB of 5v68 and protomers CB of 4kwe, protomers A and B from 5v68 are similar with protomers C and B of 4kwe. Glu231 (shown as green sphere) from protomer C of [[5v68|5v68]] and Glu231 from protomer A of [[4kwe|4kwe]] are far apart. 5V68 with bound GDP superimposed onto 2Q1Y with bound GTP. Color scheme is as follows, 5v68 blue, 2q1y green, nucleotides orange spheres, Glu231 green spheres, phosphate red spheres. Click here to see animation of this scene. To generate this trimer (2q1y), A1 A2 A3, the crystal symmetry molecules neighboring chain A2 that exhibit the inter-subunit interface were used. Only chains A1 and A2 were used for the superimposition. Again, protomers A and B from present study are similar with the top two protomers A1 and A2 from 2q1y with an r.m.s.d of 2.1Å. The distance of their respective Glu231 is approximately 63Å. 4KWE with bound GDP superimposed onto 2Q1Y with bound GTP. Color scheme is as follows, 4kwe yellow, 2q1y green, nucleotides orange spheres, Glu231 green spheres. Click here to see animation of this scene. Superimposition of 4kwe and 2q1y reveals an r.m.s.d. of 2.8Å between the trimers and a 12.5Å distance between their respective Glu231’s of A and A3, showing that these structures are relatively similar. The distances between Glu231 of 5v68 from protomer C is far greater than 12.5Å and the interaction with the middle protomers of 4kwe and 2q1y with protomer C of 5v68 involve the T9 loop residue Glu231, which is not the case in the other structures. Crystal structure of protomers A and B of 5V68 (gray). A zoom-in of the inter-subunit interface with bound GDP (orange). Helix H11 is shown in green. Helices η1, H7, and loop T6 are shown in blue. Switch I (T3 loop) is disordered surrounded by a cloud. Switch II (sH2) is shown in magenta. The top two protomers of all three structures (AB for 5v68, A1 A2 for 2q1y, and CB for 4kwe) all exhibit a similar inter-subunit interface. This interaction between protomers A and B of 5V68 involve the T6 and T7 loops, helices: H11, η1, and H7. Protomer A of our structure “sits” on the helices η1, H7 and loop T6 (all shown in blue) from protomer B. This brings the T7 loop’s (shown in red) residues Asn205, Asp207 and Asp210 of protomer A of 5v68 within 16Å of GDP from protomer B, forming the GTPase active site. The T3 loop is disordered or in its OFF position (surrounded by magenta cloud). Helix sH2 is also OFF because there is no hydrogen network (shown in magenta). Crystal structure of protomer B and C of 5V68. Protomer B is shown in gray, the T9 loop in brown, T11 in cyan; and the N-terminal of protomer C is shown in green, C-terminal blue, helix H8 yellow, the T7 loop red, and the switches in magenta. PO4 binding site. Glu231 from protomer B is shown in brown, while Glu274 from protomer is in gray. The residues in green are from protomer C. PDB reference: FtsZ from Mycobacterium tuberculosis, 5v68 References
| |||||||||||
