Biology subjects

Schneider, A.

Publications and source records attributed to Schneider, A..

3 recordsLinked to original sources

bioRxiv2018

Sample Preparation by Easy Extraction and Digestion (SPEED) - A Universal, Rapid, and Detergent-free Protocol for Proteomics based on Acid Extraction

Mass spectrometry is the method of choice for deep and comprehensive analysis of proteomes and has become a key technology to support the progress in life science and biomedicine. However, sample preparation in proteomics is not standardized and contributes to a lack of reproducibility. The main challenge is to extract all proteins in a manner that enables efficient digestion into peptides and is compatible with subsequent mass spectrometric analysis. Current methods are based on the idea of removing detergents or chaotropic agents during sample processing, which are essential for protein extraction but interfere with digestion and LC-MS. These multi-step preparations are prone to losses, biases and contaminations, while being time-consuming and labor-intensive.\n\nWe report a universal detergent-free method, named Sample Preparation by Easy Extraction and Digestion (SPEED), which is based on a simple three-step procedure, acidification, neutralization and digestion. SPEED is a one-pot method for peptide generation from various sources and is easily applicable even for lysis-resistant sample types as pure trifluoroacetic acid (TFA) is used for highly efficient protein extraction. SPEED-based sample processing is highly reproducible, provides exceptional peptide yields and enables preparation even of tissue samples with less than 15 min hands-on time and without any special equipment. Evaluation of SPEED performance revealed, that the number of quantified proteins and the quantitative reproducibility are superior compared to the well-established sample processing protocols FASP, ISD-Urea and SP3 for various sample types, including human cells, bacteria and tissue, even at low protein starting amounts.

systems biology↗

bioRxiv2017

A molecular model of the mitochondrial genome segregation machinery in Trypanosoma brucei

In almost all eukaryotes mitochondria maintain their own genome. Despite the discovery more than 50 years ago still very little is known about how the genome is properly segregated during cell division. The protozoan parasite Trypanosoma brucei contains a single mitochondrion with a singular genome the kinetoplast DNA (kDNA). Electron microscopy studies revealed the tripartite attachment complex (TAC) to physically connect the kDNA to the basal body of the flagellum and to ensure proper segregation of the mitochondrial genome via the basal bodies movement, during cell cycle. Using super-resolution microscopy we precisely localize each of the currently known unique TAC components. We demonstrate that the TAC is assembled in a hierarchical order from the base of the flagellum towards the mitochondrial genome and that the assembly is not dependent on the kDNA itself. Based on biochemical analysis the TAC consists of several non-overlapping subcomplexes suggesting an overall size of the TAC exceeding 2.8 mDa. We furthermore demonstrate that the TAC has an impact on mitochondrial organelle positioning however is not required for proper organelle biogenesis or segregation.\n\nSignificance StatementMitochondrial genome replication and segregation are essential processes in most eukaryotic cells. While replication has been studied in some detail much less is known about the molecular machinery required distribute the replicated genomes. Using super-resolution microscopy in combination with molecular biology and biochemistry we show for the first time in which order the segregation machinery is assembled and that it is assembled de novo rather than in a semi conservative fashion in the single celled parasite Trypanosoma brucei. Furthermore, we demonstrate that the mitochondrial genome itself is not required for assembly to occur. It seems that the physical connection of the mitochondrial genome to cytoskeletal elements is a conserved feature in most eukaryotes, however the molecular components are highly diverse.\n\nAbbreviation

cell biology↗

bioRxiv2017

Biogenesis of a mitochondrial DNA inheritance machinery in the mitochondrial outer membrane

Mitochondria cannot form de novo but require mechanisms that mediate their inheritance to daughter cells. The parasitic protozoan Trypanosoma brucei has a single mitochondrion with a single-unit genome that is physically connected across the mitochondrial membranes to the basal body of the flagellum. This connection, termed tripartite attachment complex (TAC), is essential for the segregation of the replicated mitochondrial genomes prior to cytokinesis. Here we identify a protein complex consisting of three integral mitochondrial outer membrane proteins - TAC60, TAC42 and TAC40 - which are essential subunits of the TAC. TAC60 contains separable mitochondrial import and TAC-sorting signals and its biogenesis depends on the main outer membrane protein translocase. TAC40 is a member of the mitochondrial porin family, whereas TAC42 represents a novel class of mitochondrial outer membrane {beta}-barrel proteins. Consequently TAC40 and TAC42 contain C-terminal {beta}-signals. Thus in trypanosomes the highly conserved {beta}-barrel protein assembly machinery plays a major role in the biogenesis of its unique mitochondrial genome segregation system.

biochemistry↗