Triphosphate structure of guanylate-binding protein 1 and implications for nucleotide binding and GTPase mechanism

Abstract

The interferon-gamma-induced guanylate-binding protein 1 (GBP1) belongs to a special class of large GTP- binding proteins of 60-100 kDa with unique characteristics. Here we present the structure of human GBP1 in complex with the non-hydrolysable GTP analogue GppNHp. Basic features of guanine nucleotide binding, such as the P-loop orientation and the Mg(2+) co-ordination, are analogous to those of Ras-related and heterotrimeric GTP-binding proteins. However, the glycosidic bond and thus the orientation of the guanine base and its interaction with the protein are very different. Furthermore, two unique regions around the base and the phosphate-binding areas, the guanine and the phosphate caps, respectively, give the nucleotide-binding site a unique appearance not found in the canonical GTP-binding proteins. The phosphate cap, which constitutes the region analogous to switch I, completely shields the phosphate-binding site from solvent such that a potential GTPase-activating protein cannot approach. This has consequences for the GTPase mechanism of hGBP1 and possibly of other large GTP-binding proteins.

Guanylate-Binding Protein-1 Expression Is Selectively Induced by Inflammatory Cytokines and Is an Activation Marker of Endothelial Cells during Inflammatory Diseases

“…15,16 GBPs have a concentration-dependent intrinsic high-turnover GTPase activity. [17][18][19] In particular, based on the crystal structure of GBP-1 20,21 and on biochemical considerations, it was proposed that GBP-1 belongs to the group of large GTP-binding proteins such as Mx and dynamin, all of which have a similar domain composition and GTPase activity, although sequence homology is very low. 20 We have shown that GBP-1 is the key and selective mediator of the anti-proliferative effect of ICs on both microvascular and macrovascular endothelial cells in vitro and that GBP-1 expression was inversely related with cell proliferation in vessel endothelial cells of Kaposi's sarcoma (KS) in vivo.…”

Sequence Analysis of LRPPRC and Its SEC1 Domain Interaction Partners Suggests Roles in Cytoskeletal Organization, Vesicular Trafficking, Nucleocytosolic Shuttling, and Chromosome Activity

“…GBP1 is among a family of large GTPbinding proteins whose prototypes are the microtubule-associated dynamins that coordinate microtubule organization and mediate vesicle trafficking [39]. Members of the family include the interferon-induced GBPs [40], yeast VP and yeast mitochondrial MGM1 thought to be involved in partitioning of mitochondrial DNA [39]. The N-terminal residues (6-372) of CECR2 (Fig.…”

“…The N-terminal residues (6-372) of CECR2 (Fig. 9B) show a predicted structural homology with the extended α-helical Cterminal portion of human GBP1 that does not exhibit the correspondent GTP-binding domain, but corresponds to the Middle and GED (GTPase effector domain) domains of dynamin that are involved in assembly of the multi-subunit complexes involved in endocytosis, synaptic vesicle recycling, caveolae internalization and vesicular trafficking in general [40,41,42]. The Pfam search indicated a well-conserved AT-Hook motif within the GBP homology domain (CECR2 residues 198-210) (Fig.…”

Charakterisierung molekularer Mechanismen der anti-angiogenen Aktivität von GBP-1 in Endothelzellen

“…Die Bindung von GTP an GBP-1 bewirkt eine Oligomerisierung, wodurch sich die intrinsische Hydrolyseaktivät des Proteins stark erhöht und GTP über GDP zu GMP und anorganischem Phosphat hydrolysiert wird (Prakash et al, 2000b;Schwemmle and Staeheli, 1994). GBP-1 hydrolysiert GTP unabhängig von Guaninnukleotid-Austauschfaktoren (GEF),…”