PDBsum entry: 1z5w

Structural protein

PDB id: 1z5w

Contents

Protein chain

409 a.a. *

Ligands

GTP

Metals

_MG

* Residue conservation analysis

PDB id:

1z5w

Name:

Structural protein

Title:

Crystal structure of gamma-tubulin bound to gtp

Structure:

Tubulin gamma-1 chain. Chain: a. Synonym: gamma-1 tubulin, gamma-tubulin complex component 1, gcp-1. Engineered: yes

Source:

Homo sapiens. Human. Organism_taxid: 9606. Gene: tubg1, tubg. Expressed in: spodoptera frugiperda. Expression_system_taxid: 7108.

Resolution:

3.00Å R-factor: 0.247 R-free: 0.309

Authors:

H.A.Aldaz,L.M.Rice,T.Stearns,D.A.Agard

Key ref:

H.Aldaz et al. (2005). Insights into microtubule nucleation from the crystal structure of human gamma-tubulin. Nature, 435, 523-527. PubMed id: 15917813 DOI: 10.1038/nature03586

Date:

20-Mar-05 Release date: 31-May-05

Protein chain

P23258  (TBG1_HUMAN) -  Tubulin gamma-1 chain

Seq: 451 a.a.

Struc: 409 a.a.*

* PDB and UniProt seqs differ at 2 residue positions (black crosses)

 Gene Ontology (GO) functional annotation 

• Cellular component: protein complex (16 terms)
• Biological process: microtubule-based process (7 terms)
• Biochemical function: nucleotide binding (5 terms)

DOI no: 10.1038/nature03586

Nature 435:523-527 (2005)

PubMed id: 15917813

Insights into microtubule nucleation from the crystal structure of human gamma-tubulin.

H.Aldaz, L.M.Rice, T.Stearns, D.A.Agard.

ABSTRACT

Microtubules are hollow polymers of alphabeta-tubulin that show GTP-dependent assembly dynamics and comprise a critical part of the eukaryotic cytoskeleton. Initiation of new microtubules in vivo requires gamma-tubulin, organized as an oligomer within the 2.2-MDa gamma-tubulin ring complex (gamma-TuRC) of higher eukaryotes. Structural insight is lacking regarding gamma-tubulin, its oligomerization and how it promotes microtubule assembly. Here we report the 2.7-A crystal structure of human gamma-tubulin bound to GTP-gammaS (a non-hydrolysable GTP analogue). We observe a 'curved' conformation for gamma-tubulin-GTPgammaS, similar to that seen for GDP-bound, unpolymerized alphabeta-tubulin. Tubulins are thought to represent a distinct class of GTP-binding proteins, and conformational switching in gamma-tubulin might differ from the nucleotide-dependent switching of signalling GTPases. A crystal packing interaction replicates the lateral contacts between alpha- and beta-tubulins in the microtubule, and this association probably forms the basis for gamma-tubulin oligomerization within the gamma-TuRC. Laterally associated gamma-tubulins in the gamma-TuRC might promote microtubule nucleation by providing a template that enhances the intrinsically weak lateral interaction between alphabeta-tubulin heterodimers. Because they are dimeric, alphabeta-tubulins cannot form microtubule-like lateral associations in the curved conformation. The lateral array of gamma-tubulins we observe in the crystal reveals a unique functional property of a monomeric tubulin.

Selected figure(s)

Figure 2.
Figure 2: bold gamma--tubulin adopts a curved conformation. Structural superposition of -tubulin conformations onto -tubulin using the rigid N-terminal domain. a, The -tubulin structure (blue) and the curved -tubulin structure (green) share a similar arrangement of the H6 -H7 segment (left) and of intermediate domains (right). b, The -tubulin structure (blue) and the straight -tubulin structure (pink) show characteristic differences in the orientation of the H6 -H7 segment (left) and the intermediate domain (right). c, Comparison between the curved (green) and straight (pink) -tubulin conformations, illustrating the characteristic differences in the H6 -H7 segment (left) and the intermediate domain (right).

Figure 3.
Figure 3: Lateral interactions between bold gamma--tubulins resemble lateral interactions in the microtubule lattice. a, 'Minus end' views of laterally interacting -tubulins in the microtubule lattice (green) (K. Downing, personal communication), and laterally interacting -tubulins in the crystal (blue). Contact regions between monomers are indicated by the grey surfaces on the central monomer. b, Comparative 'outside' views of the same interactions, showing a similar pitch for both. c, Lateral interaction regions of -tubulin in the microtubule lattice (green) and -tubulin in the crystal (blue) are indicated on the molecular surface. Microtubule and -tubulin crystal interaction footprints are very similar. d, Comparison of the buried surface area (in Å2) at each position for -tubulin lateral interactions in the microtubule lattice (left) and -tubulin crystal interactions (right). Virtually identical regions of the structure are involved in both interactions.

The above figures are reprinted by permission from Macmillan Publishers Ltd: Nature (2005, 435, 523-527) copyright 2005.

Figures were selected by the author.