SASDBR4: Leishmania braziliensis Activator of Hsp90 ATPase-1 (LbAha1)

Basic information

• Entry: Database: SASBDB / ID: SASDBR4

Sample

Leishmania braziliensis Activator of Hsp90 ATPase-1 (LbAha1)

• Activator of Hsp90 ATPase-1 (protein), LbAha1, Leishmania braziliensis

• Biological species: Leishmania braziliensis (eukaryote)
• Citation: Journal: PLoS One / Year: 2013; Title: Low resolution structural studies indicate that the activator of Hsp90 ATPase 1 (Aha1) of Leishmania braziliensis has an elongated shape which allows its interaction with both N- and M-domains of Hsp90.; Authors: Thiago V Seraphim / Marina M Alves / Indjara M Silva / Francisco E R Gomes / Kelly P Silva / Silvane M F Murta / Leandro R S Barbosa / Júlio C Borges / ; Abstract: The Hsp90 molecular chaperone is essential for protein homeostasis and in the maturation of proteins involved with cell-cycle control. The low ATPase activity of Hsp90 is critical to drive its functional cycle, which is dependent on the Hsp90 cochaperones. The Activator of Hsp90 ATPase-1 (Aha1) is a protein formed by two domains, N- and C-terminal, that stimulates the Hsp90 ATPase activity by several folds. Although the relevance of Aha1 for Hsp90 functions has been proved, as well as its involvement in the desensitization to inhibitors of the Hsp90, the knowledge on its overall structure and behavior in solution is limited. In this work we present the functional and structural characterization of Leishmania braziliensis Aha1 (LbAha1). This protozoan is the causative agent of cutaneous and mucocutaneous leishmaniasis, a neglected disease. The recombinant LbAha1 behaves as an elongated monomer and is organized into two folded domains interconnected by a flexible linker. Functional experiments showed that LbAha1 interacts with L. braziliensis Hsp90 (LbHsp90) with micromolar dissociation constant in a stoichiometry of 2 LbAha1 to 1 LbHsp90 dimer and stimulates 10-fold the LbHsp90 ATPase activity showing positive cooperativity. Furthermore, the LbHsp90::LbAha1 complex is directed by enthalphy and opposed by entropy, probably due to the spatial freedom restrictions imposed by the proteins' interactions. Small-angle X-ray scattering data allowed the reconstruction of low resolution models and rigid body simulations of LbAha1, indicating its mode of action on LbHsp90. Western blot experiments allowed Aha1 identification (as well as Hsp90) in three Leishmania species at two temperatures, suggesting that Aha1 is a cognate protein. All these data shed light on the LbAha1 mechanism of action, showing that it has structural dimensions and flexibility that allow interacting with both N-terminal and middle domains of the LbHsp90.

Contact author

• Júlio Borges (Instituto de Química de São Carlos, São Carlos - SP - Brasil)

Models

• Model #525: ; Type: mix / Software: EOM / Radius of dummy atoms: 1.90 A / Chi-square value: 3.869089 / P-value: 0.207500; Search similar-shape structures of this assembly by Omokage search (details)
• Model #526: ; Type: dummy / Software: DAMMIN / Radius of dummy atoms: 1.90 A / Chi-square value: 1.565001 / P-value: 0.028000; Search similar-shape structures of this assembly by Omokage search (details)

Sample

• Sample: Name: Leishmania braziliensis Activator of Hsp90 ATPase-1 (LbAha1); Specimen concentration: 1.10-3.20
• Buffer: Name: sodium phosphate / pH: 7 / Composition: 50 mM NaCl, 2 mM EDTA, 1 mM β-mercaptoethanol

Entity #339

Name: LbAha1 / Type: protein / Description: Activator of Hsp90 ATPase-1 / Formula weight: 38.254 / Num. of mol.: 1 / Source: Leishmania braziliensis
Sequence:

MAKVGEGDPR WIVSERTDGA NVNSWHWEER DLSQHTHDKL KSVFAEHAIP VPADMATSVE YLKIEEVSEI SGDVTVAQRK GKMMCYFELK MSLRWVGKMS GADQVIRGKM EVAEVDHDGF KDEYDIAVTC QENDSAAQLL ESVVQVAGRS TVRQGIATFF DALFAEYHIG KQLKSGAALP PPPPPLSASA STTLATNAAA GKKSVTPSKS SSGSGDENTS FSWKMRWGAP VAELYAAMTD PSRVSVYTRS PASMDVKAGG LFSFLGGVIS GYYVDVQPST LIRQQWRLSS WPVGVHSSVV LQLVKEEPGV TTLEFTQSGI PAGQLQSVQE GWKANFFEAI KVVFGYSLEY I

Experimental information

• Beam: Instrument name: Brazilian Synchrotron Light Laboratory SAXS2 Beamline; City: Campinas / 国: Brazil / Type of source: X-ray synchrotron
• Detector: Name: MAR 165 CCD

Scan

Title: Activator of Hsp90 ATPase-1 (LbAha1) / Measurement date: Jun 1, 2013 / Exposure time: 300 sec. / Number of frames: 3 / Unit: 1/nm /

	Min	Max
Q	0.1769	3.517

Distance distribution function P(R)

Sofotware P(R): GNOM 4.5a / Number of points: 244 /

	Min	Max
Q	0.01769	0.3517
P(R) point	1	244
R	0	145

Result

Experimental MW: 47 kDa / Type of curve: merged
Comments: Ab initio model of Leishmania braziliensis Activator of Hsp90 ATPase-1 (LbAha1) and Ensemble Optimization Method analysis on LbAha1 conformational dynamics. Results showed that LbAha1 is remarkably flexible.

	P(R)	Guinier
Forward scattering, I0	0.03091	0.03
Radius of gyration, Rg	3.88 nm	3.56 nm

	Min	Max
D	-	14.5
Guinier point	3	14