Solution structure of subunit a, a104â363, of the Saccharomyces cerevisiae V-ATPase and the importance of its C-terminus in structure formation.
J Bioenerg Biomembr
; 44(3): 341-50, 2012 Jun.
Article
em En
| MEDLINE
| ID: mdl-22562380
ABSTRACT
The 95 kDa subunit a of eukaryotic V-ATPases consists of a C-terminal, ion-translocating part and an N-terminal cytosolic domain. The latter's N-terminal domain (~40 kDa) is described to bind in an acidification-dependent manner with cytohesin-2 (ARNO), giving the V-ATPase the putative function as pH-sensing receptor. Recently, the solution structure of the very N-terminal segment of the cytosolic N-terminal domain has been solved. Here we produced the N-terminal truncated form SCa104â363 of the N-terminal domain (SCa1â363) of the Saccharomyces cerevisiae V-ATPase and determined its low resolution solution structure, derived from SAXS data. SCa104â363 shows an extended S-like conformation with a width of about 3.88 nm and a length of 11.4 nm. The structure has been superimposed into the 3D reconstruction of the related A1A0 ATP synthase from Pyrococcus furiosus, revealing that the SCa104â363 fits well into the density of the collar structure of the enzyme complex. To understand the importance of the C-terminus of the protein SCa1â363, and to determine the localization of the N- and C-termini in SCa104â363, the C-terminal truncated form SCa106â324 was produced and analyzed by SAXS. Comparison of the SCa104â363 and SCa106â324 shapes showed that the additional loop region in SCa104â363 consists of the C-terminal residues. Whereas SCa104â363 is monomeric in solution, SCa106â324 forms a dimer, indicating the importance of the very C-terminus in structure formation. Finally, the solution structure of SCa104â363 and SCa106â324 will be discussed in terms of the topological arrangement of subunit a and cytoheisn-2 in V-ATPases.
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Base de dados:
MEDLINE
Assunto principal:
Saccharomyces cerevisiae
/
ATPases Vacuolares Próton-Translocadoras
Idioma:
En
Ano de publicação:
2012
Tipo de documento:
Article