Crystal structures of the vitamin D-binding protein and its complex with actin: Structural basis of the actin-scavenger system

Otterbein, Ludovic R.; Cosio, Christophe; Graceffa, Philip; Domínguez, Roberto

doi:10.1073/pnas.122126299

Cited by 148 publications

(129 citation statements)

References 38 publications

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“…Distinct binding regions within the 458 amino acid sequence of DBP have been identified. Analysis of the crystal structure of DBP (bound to either vitamin D 3 or actin) has confirmed previous studies that the vitamin D sterol binding segment resides in the N-terminal domain (amino acids 35-49) (Haddad et al, 1992;Swamy et al, 1997), and also revealed that actin interacts with distinct amino acid sequences in all three DBP domains Otterbein et al, 2002;Swamy et al, 2002;Verboven et al, 2002). Recently, our lab has identified a C5a chemotactic cofactor region in the N-terminal domain (amino acids 130-149), a sequence distinct from either the vitamin D or G-actin binding regions (Zhang and Kew, 2004).…”

Section: Introductionsupporting

confidence: 81%

Selective inhibition of the C5a chemotactic cofactor function of the Vitamin D binding protein by 1,25(OH)2 Vitamin D3

Shah

DiMartino

Trujillo

et al. 2006

Molecular Immunology

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The vitamin D binding protein (DBP) is a multifunctional plasma protein that can significantly enhance the chemotactic response to complement fragment C5a. The chemotactic cofactor function of DBP requires cell surface binding in order to mediate this process. The goal of this study was to investigate the effect of ligating DBP with its two primary physiological ligands, vitamin D and Gactin, on both binding to neutrophils and the ability to enhance chemotaxis to C5a. There was no difference in neutrophil binding between of the holo (bound) forms versus the apo (unbound) form of radioiodinated DBP, indicating that the cell binding region of DBP likely is distinct from the vitamin D sterol and G-actin binding sites. Likewise, G-actin, 25(OH)D 3 , and G-actin plus 25(OH) D 3 bound to DBP did not alter its capacity to enhance chemotaxis toward C5a. However, the active form of vitamin D (1,25(OH) 2 D 3 ) completely eliminated the chemotactic cofactor function of DBP. Dose response curves demonstrated that as little as 1 pM 1,25(OH) 2 D 3 significantly inhibited chemotaxis enhancement. Moreover, at physiological concentrations 1,25(OH) 2 D 3 needs to be bound to DBP to mediate the inhibitory effect. Neutrophil chemotaxis to optimal concentrations of C5a, formyl peptide, CXCL8 or leukotriene B 4 was not altered by 1,25(OH) 2 D 3 indicating that the active vitamin does not have a global inhibitory effect on neutrophil chemotaxis. Finally, inhibition of cell surface alkaline phosphatase with sodium orthovanadate completely reversed the inhibitory effect of 1,25(OH) 2 D 3 . These results indicate that the cell binding and co-chemotactic functions of DBP are not altered when the protein binds G-actin and/or vitamin D. Furthermore, the co-chemotactic signal from DBP can be eliminated or counteracted by 1,25(OH) 2 D 3 .

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Section: Introductionsupporting

confidence: 81%

Selective inhibition of the C5a chemotactic cofactor function of the Vitamin D binding protein by 1,25(OH)2 Vitamin D3

Shah

DiMartino

Trujillo

et al. 2006

Molecular Immunology

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“…Actin's natural tendency to polymerize constitutes an obstacle to crystallization. Different approaches have been used to overcome this problem, including the crystallization of complexes of actin with actin-binding proteins (ABPs) (20,(22)(23)(24)(25)(26) and toxins (27), and blocking actin polymerization by mutagenesis (28) or chemical cross-linking (29). We chose to attempt Author contributions: E.D.K.…”

Section: Resultsmentioning

confidence: 99%

“…The extent of actin phosphorylation, which is very low in growing vegetative cells, begins to increase [12][13][14][15][16][17][18][19][20][21][22][23][24] h into the developmental cycle, reaching Ϸ50% of the total actin at Ϸ36 h (9)(10)(11). At this high level of actin phosphorylation, the spores of the mature fruiting bodies remain viable for Ϸ20 days, at which time viability and actin phosphorylation levels both decrease, disappearing entirely by Ϸ30 days.…”

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confidence: 99%

Modulation of actin structure and function by phosphorylation of Tyr-53 and profilin binding

Baek

Xiong

Ferrón

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

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On starvation, Dictyostelium cells aggregate to form multicellular fruiting bodies containing spores that germinate when transferred to nutrient-rich medium. This developmental cycle correlates with the extent of actin phosphorylation at Tyr-53 (pY53-actin), which is low in vegetative cells but high in viable mature spores. Here we describe high-resolution crystal structures of pY53-actin and unphosphorylated actin in complexes with gelsolin segment 1 and profilin. In the structure of pY53-actin, the phosphate group on Tyr-53 makes hydrogen-bonding interactions with residues of the DNase I-binding loop (D-loop) of actin, resulting in a more stable conformation of the D-loop than in the unphosphorylated structures. A more rigidly folded D-loop may explain some of the previously described properties of pY53-actin, including its increased critical concentration for polymerization, reduced rates of nucleation and pointed end elongation, and weak affinity for DNase I. We show here that phosphorylation of Tyr-53 inhibits subtilisin cleavage of the D-loop and reduces the rate of nucleotide exchange on actin. The structure of profilin-Dictyostelium-actin is strikingly similar to previously determined structures of profilin-␤-actin and profilin-␣-actin. By comparing this representative set of profilin-actin structures with other structures of actin, we highlight the effects of profilin on the actin conformation. In the profilin-actin complexes, subdomains 1 and 3 of actin close around profilin, producing a 4.7°rotation of the two major domains of actin relative to each other. As a result, the nucleotide cleft becomes moderately more open in the profilin-actin complex, probably explaining the stimulation of nucleotide exchange on actin by profilin.actin phosphorylation ͉ profilin-actin structure ͉ pY53-actin structure ͉ Dictyostelium discoideum actin ͉ gelsolin-actin structure

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“…Toxofilin, like gelsolin (21), vitamin D-binding protein (22), formin (23), WH2 (15), and ciboulot (24), presents a helix (helix 3) that binds in the cleft between actin subdomains 1 and 3 (13). Toxofilin 69-196 helix 3 superimposes particularly well with the helix of WH2 (Fig.…”

Section: Discussionmentioning

confidence: 99%

Toxofilin from Toxoplasma gondii forms a ternary complex with an antiparallel actin dimer

Lee

Hayes

Rębowski

et al. 2007

Proc. Natl. Acad. Sci. U.S.A.

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Many human pathogens exploit the actin cytoskeleton during infection, including Toxoplasma gondii, an apicomplexan parasite related to Plasmodium, the agent of malaria. One of the most abundantly expressed proteins of T. gondii is toxofilin, a monomeric actin-binding protein (ABP) involved in invasion. Toxofilin is found in rhoptry and presents an N-terminal signal sequence, consistent with its being secreted during invasion. We report the structure of toxofilin amino acids 69 -196 in complex with the host mammalian actin. Toxofilin presents an extended conformation and interacts with an antiparallel actin dimer, in which one of the actins is related by crystal symmetry. Consistent with this observation, analytical ultracentrifugation analysis shows that toxofilin binds two actins in solution. Toxofilin folds into five consecutive helices, which form three relatively independent actin-binding sites. Helices 1 and 2 bind the symmetry-related actin molecule and cover its nucleotide-binding cleft. Helices 3-5 bind the other actin and constitute the primary actin-binding region. Helix 3 interacts in the cleft between subdomains 1 and 3, a common binding site for most ABPs. Helices 4 and 5 wrap around actin subdomain 4, and residue Gln-134 of helix 4 makes a hydrogen-bonding contact with the nucleotide in actin, both of which are unique features among ABPs. Toxofilin dramatically inhibits nucleotide exchange on two actin molecules simultaneously. This effect is linked to the formation of the antiparallel actin dimer because a construct lacking helices 1 and 2 binds only one actin and inhibits nucleotide exchange less potently.actin cytoskeleton ͉ crystal structure ͉ pathogens ͉ analytical ultracentrifugation

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Crystal structures of the vitamin D-binding protein and its complex with actin: Structural basis of the actin-scavenger system

Cited by 148 publications

References 38 publications

Selective inhibition of the C5a chemotactic cofactor function of the Vitamin D binding protein by 1,25(OH)2 Vitamin D3

Selective inhibition of the C5a chemotactic cofactor function of the Vitamin D binding protein by 1,25(OH)2 Vitamin D3

Modulation of actin structure and function by phosphorylation of Tyr-53 and profilin binding

Toxofilin from Toxoplasma gondii forms a ternary complex with an antiparallel actin dimer

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