Dataset Information

BtubA-BtubB heterodimer is an essential intermediate in protofilament assembly.

ABSTRACT: BACKGROUND:BtubA and BtubB are two tubulin-like genes found in the bacterium Prosthecobacter. Our work and a previous crystal structure suggest that BtubB corresponds to alpha-tubulin and BtubA to beta-tubulin. A 1:1 mixture of the two proteins assembles into tubulin-like protofilaments, which further aggregate into pairs and bundles. The proteins also form a BtubA/B heterodimer, which appears to be a repeating subunit in the protofilament. METHODOLOGY/PRINCIPAL FINDINGS:We have designed point mutations to disrupt the longitudinal interfaces bonding subunits into protofilaments. The mutants are in two classes, within dimers and between dimers. We have characterized one mutant of each class for BtubA and BtubB. When mixed 1:1 with a wild type partner, none of the mutants were capable of assembly. An excess of between-dimer mutants could depolymerize preformed wild type polymers, while within-dimer mutants had no activity. CONCLUSIONS:An essential first step in assembly of BtubA + BtubB is formation of a heterodimer. An excess of between-dimer mutants depolymerize wild type BtubA/B by sequestering the partner wild type subunit into inactive dimers. Within-dimer mutants cannot form dimers and have no activity.

SUBMITTER: Sontag CA

PROVIDER: S-EPMC2746283 | biostudies-literature | 2009 Sep

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

BtubA-BtubB heterodimer is an essential intermediate in protofilament assembly.

Sontag Christopher A CA Sage Harvey H Erickson Harold P HP

PloS one 20090929 9

<h4>Background</h4>BtubA and BtubB are two tubulin-like genes found in the bacterium Prosthecobacter. Our work and a previous crystal structure suggest that BtubB corresponds to alpha-tubulin and BtubA to beta-tubulin. A 1:1 mixture of the two proteins assembles into tubulin-like protofilaments, which further aggregate into pairs and bundles. The proteins also form a BtubA/B heterodimer, which appears to be a repeating subunit in the protofilament.<h4>Methodology/principal findings</h4>We have d ...[more]

PMID: 19787042

Similar Datasets

Project description:Detailed structural studies of amyloid fibrils can elucidate the way in which their constituent polypeptides are folded and self-assemble, and exert their neurotoxic effects in Alzheimer's disease (AD). We have previously reported that when aqueous solutions of the N-terminal hydrophilic peptides of AD beta-amyloid (A beta) are gradually dried in a 2-Tesla magnetic field, they form highly oriented fibrils that are well suited to x-ray fiber diffraction. The longer, more physiologically relevant sequences such as A beta(1-40) have not been amenable to such analysis, owing to their strong propensity to polymerize and aggregate before orientation is achieved. In seeking an efficient and inexpensive method for rapid screening of conditions that could lead to improved orientation of fibrils assembled from the longer peptides, we report here that the birefringence of a small drop of peptide solution can supply information related to the cooperative packing of amyloid fibers and their capacity for magnetic orientation. The samples were examined by electron microscopy (negative and positive staining) and x-ray diffraction. Negative staining showed a mixture of straight and twisted fibers. The average width of both types was approximately 70 A, and the helical pitch of the latter was approximately 460 A. Cross sections of plastic-embedded samples showed a approximately 60-A-wide tubular structure. X-ray diffraction from these samples indicated a cross-beta fiber pattern, characterized by a strong meridional reflection at 4.74 A and a broad equatorial reflection at 8.9 A. Modeling studies suggested that tilted arrays of beta-strands constitute tubular, 30-A-diameter protofilaments, and that three to five of these protofilaments constitute the A beta fiber. This type of structure--a multimeric array of protofilaments organized as a tubular fibril--resembles that formed by the shorter A beta fragments (e.g., A beta(6-25), A beta(11-25), A beta(1-28)), suggesting a common structural motif in AD amyloid fibril organization.

Dataset Information

BtubA-BtubB heterodimer is an essential intermediate in protofilament assembly.

Publications

BtubA-BtubB heterodimer is an essential intermediate in protofilament assembly.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets