Teresa Ruiz - Academia.edu (original) (raw)

Uploads

Papers by Teresa Ruiz

Journal of Structural Biology, 2001

We determined the structure of the V 1 -ATPase from Manduca sexta to a resolution of 1.8 nm, whic... more We determined the structure of the V 1 -ATPase from Manduca sexta to a resolution of 1.8 nm, which for the first time reveals internal features of the enzyme. The V 1 -ATPase consists of a headpiece of 13.5 nm in diameter, with six elongated subunits, A 3 and B 3 , of approximately equal size, and a stalk of 6 nm in length that connects V 1 with the membranebound domain, V O . At the center of the molecule is a cavity that extends throughout the length of the A 3 B 3 hexamer. Inside the cavity the central stalk can be seen connected to only two of the catalytic A subunits. The structure was obtained by a combination of the Random Conical Reconstruction Technique and angular refinements. Additional recently developed techniques that were used include methods for simultaneous translational rotational alignment of the 0°images, contrast transfer function correction for tilt images, and the Two-Step Radon Inversion Algorithm.

Journal of Molecular Biology, 2002

The mitochondrial outer membrane contains a multi-subunit machinery responsible for the specific ... more The mitochondrial outer membrane contains a multi-subunit machinery responsible for the specific recognition and translocation of precursor proteins. This translocase of the outer membrane (TOM) consists of three receptor proteins, Tom20, Tom22 and Tom70, the channel protein Tom40, and several small Tom proteins. Single-particle electron microscopy analysis of the Neurospora TOM complex has led to different views with two or three stain-filled centers resembling channels. Based on biochemical and electron microscopy studies of the TOM complex isolated from yeast mitochondria, we have discovered the molecular reason for the different number of channel-like structures. The TOM complex from wild-type yeast contains up to three stain-filled centers, while from a mutant yeast selectively lacking Tom20, the TOM complex particles contain only two channel-like structures. From mutant mitochondria lacking Tom22, native electrophoresis separates an approximately 80 kDa subcomplex that consists of Tom40 only and is functional for accumulation of a precursor protein. We conclude that while Tom40 forms the import channels, the two receptors Tom22 and Tom20 are required for the organization of Tom40 dimers into larger TOM structures.

Journal of Structural Biology, 2006

The structure of complex I from Yarrowia lipolytica was determined by three-dimensional electron ... more The structure of complex I from Yarrowia lipolytica was determined by three-dimensional electron microscopy. A random conical data set was collected from deep stain embedded particles. More than 14 000 image pairs were analyzed. Through extensive classiWcation combined with three-dimensional reconstruction, it was possible for the Wrst time to show a much more detailed substructure of the complex. The peripheral arm is subdivided in at least six domains. The membrane arm shows two major protrusions on its matrix facing side and exhibits a channel like feature on the side facing the cytoplasm. Structures resembling a tether connecting the subunits near the catalytic center with the protrusions of the membrane arm provide a second connection between matrix and membrane domain.

Embo Journal, 2001

Replicative helicases are motor proteins that unwind DNA at replication forks. Escherichia coli D... more Replicative helicases are motor proteins that unwind DNA at replication forks. Escherichia coli DnaB is the best characterized member of this family of enzymes. We present the 26 A Ê resolution three-dimensional structure of the DnaB hexamer in complex with its loading partner, DnaC, obtained from cryo-electron microscopy. Analysis of the volume brings insight into the elaborate way the two proteins interact, and provides a structural basis for control of the symmetry state and inactivation of the helicase by DnaC. The complex is arranged on the basis of interactions among DnaC and DnaB dimers. DnaC monomers are observed for the ®rst time to arrange as three dumb-bell-shaped dimers that interlock into one of the faces of the helicase. This could be responsible for the freezing of DnaB in a C 3 architecture by its loading partner. The central channel of the helicase is almost occluded near the end opposite to DnaC, such that even single-stranded DNA could not pass through. We propose that the DnaB N-terminal domain is located at this face.