Henrik Zauber

Max Planck Institute of Molecular Plant Physiology, Potsdam, Brandenburg, Germany

Are you Henrik Zauber?

Claim your profile

Publications (11)86.71 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Clathrin-mediated endocytosis is the major mechanism for eukaryotic plasma membrane-based proteome turn-over. In plants, clathrin-mediated endocytosis is essential for physiology and development, but the identification and organization of the machinery operating this process remains largely obscure. Here, we identified an eight-core-component protein complex, the TPLATE complex, essential for plant growth via its role as major adaptor module for clathrin-mediated endocytosis. This complex consists of evolutionarily unique proteins that associate closely with core endocytic elements. The TPLATE complex is recruited as dynamic foci at the plasma membrane preceding recruitment of adaptor protein complex 2, clathrin, and dynamin-related proteins. Reduced function of different complex components severely impaired internalization of assorted endocytic cargoes, demonstrating its pivotal role in clathrin-mediated endocytosis. Taken together, the TPLATE complex is an early endocytic module representing a unique evolutionary plant adaptation of the canonical eukaryotic pathway for clathrin-mediated endocytosis.
    Cell 02/2014; 156(4):691-704. · 31.96 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Chelidonium majus and Corydalis cava are phylogenetically closely related (Papaveraceae family). The medicinal and pharmaceutical interest in these plants is based on their synthesis of pharmaceutically important compounds, such as alkaloids, flavonoids, phenolic acids and proteins. Ch. majus shoot and C. cava tuber extracts have been used in traditional folk medicine to treat many diseases, such as fungal, bacterial and viral infections, liver disorders, fever, post-traumatic, colic, abdominal and menstrual pains and even cancer. This study attempts to perform a global comparative proteomic analysis of pharmacologically important extracts from these two closely related unsequenced plant species to gain insights into the protein basis of these plant organs and to compare their common and specific proteomic compositions.We used a shotgun proteomic approach combined with label-free protein quantitation according to the exponentially modified protein abundance index (emPAI). In total, a mean number of 228 protein identification results were recorded in C. cava tuber extracts and about 1240 in Ch. majus shoot extracts. Comparative analysis revealed a similar stress and defense-related protein composition of pharmacologically active plant species and showed the presence of different pathogenesis-related and low molecular inducible antimicrobial peptides. These findings could form the basis for further elucidation of the mechanism of the strong pharmacological activities of these medicinal plant extracts.
    Fitoterapia 01/2014; · 2.23 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The plasma membrane is an important organelle providing structure, signaling and transport as major biological functions. Being composed of lipids and proteins with different physicochemical properties, the biological functions of membranes depend on specific protein-protein and protein-lipid interactions. Interactions of proteins with their specific sterol and lipid environment were shown to be important factors for protein recruitment into sub-compartmental structures of the plasma membrane. System-wide implications of altered endogenous sterol levels for membrane functions in living cells were not studied in higher plant cells. In particular, little is known how alterations in membrane sterol composition affect protein and lipid organization and interaction within membranes. Here, we conducted a comparative analysis of the plasma membrane protein and lipid composition in Arabidopsis sterol-biosynthesis mutants smt1 and ugt80A2;B1. smt1 shows general alterations in sterol composition while ugt80A2;B1 is significantly impaired in sterol glycosylation. By systematically analyzing different cellular fractions and combining proteomic with lipidomic data we were able to reveal contrasting alterations in lipid-protein interactions in both mutants, with resulting differential changes in plasma membrane signaling status.
    Frontiers in Plant Science 01/2014; 5:78. · 3.60 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: During the last decade, research on plasma membrane focused increasingly on the analysis of so-called microdomains. It has been shown that function of many membrane-associated proteins involved in signaling and transport depends on their conditional segregation within sterol-enriched membrane domains. High throughput proteomic analysis of sterol-protein interactions are often based on analyzing detergent resistant membrane fraction (DRM) enriched in sterols and associated proteins, which also contain proteins from these microdomain structures. Most studies so far focused exclusively on the characterization of DRM protein composition and abundances. This approach has received some criticism due to its unspecificity and many copurifying proteins. In this study, by a label-free quantitation approach, we extended the characterization of membrane microdomains by particularly studying distributions of each protein between DRM and detergent soluble fractions (DSF). This approach allows a more stringent definition of dynamic processes between different membrane phases and provides a means of identification of co-purifying proteins. We developed a bootstrapping algorithm, called Unicorn, allowing for robust statistical testing of alterations in the protein distribution ratios of the two different fractions. Unicorn was validated on proteomic data from methyl-beta-cyclodextrin treated plasma membranes and the sterol biosynthesis mutant smt1. Both, chemical treatment and sterol-biosynthesis mutation affected similar protein classes in their membrane phase distribution and particularly proteins with signaling and transport functions.
    Molecular &amp Cellular Proteomics 09/2013; · 7.25 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Quantitative comparative analyses of protein abundances using peptide ion intensities and their modifications have become a widely used technique in studying various biological questions. In the past years, several methods for quantitative proteomics were established using stable-isotope labeling and label-free approaches. We systematically evaluated the application of reference protein normalization (RPN) for proteomic experiments using a high mass accuracy LC-MS/MS platform. In RPN all sample peptide intensities were normalized to an average protein intensity of a spiked reference protein. The main advantage of this method is that it avoids fraction of total based relative analysis of proteomic data, which is often very much dependent on sample complexity. We could show that reference protein ion intensity sums are sufficiently reproducible to ensure a reliable normalization. We validated the RPN strategy by analyzing changes in protein abundances induced by nutrient starvation in . Beyond that, we provide a principle guideline for determining optimal combination of sample protein and reference protein load on individual LC-MS/MS systems.
    Frontiers in Plant Science 01/2013; 4:25. · 3.60 Impact Factor
  • Henrik Zauber, Waltraud X Schulze
    [Show abstract] [Hide abstract]
    ABSTRACT: The large-scale analysis of thousands of proteins under various experimental conditions or in mutant lines has gained more and more importance in hypothesis-driven scientific research and systems biology in the past years. Quantitative analysis by large scale proteomics using modern mass spectrometry usually results in long lists of peptide ion intensities. The main interest for most researchers, however, is to draw conclusions on the protein level. Postprocessing and combining peptide intensities of a proteomic data set requires expert knowledge, and the often repetitive and standardized manual calculations can be time-consuming. The analysis of complex samples can result in very large data sets (lists with several 1000s to 100 000 entries of different peptides) that cannot easily be analyzed using standard spreadsheet programs. To improve speed and consistency of the data analysis of LC-MS derived proteomic data, we developed cRacker. cRacker is an R-based program for automated downstream proteomic data analysis including data normalization strategies for metabolic labeling and label free quantitation. In addition, cRacker includes basic statistical analysis, such as clustering of data, or ANOVA and t tests for comparison between treatments. Results are presented in editable graphic formats and in list files.
    Journal of Proteome Research 09/2012; · 5.06 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: As noninvasively accessible body fluid, saliva is of growing interest in diagnostics. To exemplify the diagnostic potential of saliva, we used a mass spectrometry-based approach to gain insights into adaptive physiological processes underlying long-lasting endurance work load in a case study. Saliva was collected from male and female athlete at four diurnal time points throughout a 1060 km nonstop cycling event. Total sampling time covered 180 h comprising 62 h of endurance cycling as well as reference samples taken over 3 days before the event, and over 2 days after. Altogether, 1405 proteins and 62 metabolites were identified in these saliva samples, of which 203 could be quantified across the majority of the sampling time points. Many proteins show clear diurnal abundance patterns in saliva. In many cases, these patterns were disturbed and altered by the long-term endurance stress. During the stress phase, metabolites of energy mobilization, such as creatinine and glucose were of high abundance, as well as metabolites with antioxidant functions. Lysozyme, amylase, and proteins with redox-regulatory function showed significant increase in average abundance during work phase compared to rest or recovery phase. The recovery phase was characterized by an increased abundance of immunoglobulins. Our work exemplifies the application of high-throughput technologies to understand adaptive processes in human physiology.
    Proteomics 07/2012; 12(13):2221-35. · 4.43 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: This study reports the comprehensive comparison of (15)N metabolic labeling and label free proteomic strategies for quantitation, with particular focus on plant proteomics. Our investigation of proteome coverage, dynamic range and quantitative precision for a wide range of mixing ratios and protein loadings aim to aid the investigators in the decision making process during experimental design. One of the main characteristics of the label free strategy is the applicability to all starting material, which is a limitation to the metabolic labeling. However, particularly at mixing ratios up to 10-fold the (15)N metabolic labeling proved to be more precise. Contrary to usual practice based on the results from this study, we suggest that nonequal mixing ratios in metabolic labeling could further increase the proteome coverage for quantitation. On the other hand, the label free strategy, in combination with low protein loading allows the extension of the dynamic range for quantitation and it is more precise at very high ratios, which could be important for certain types of experiments.
    Molecular &amp Cellular Proteomics 05/2012; 11(9):619-28. · 7.25 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Plants have an unusual plastid-localized NADP-thioredoxin reductase C (NTRC) containing both an NADP-thioredoxin reductase (NTR) and a thioredoxin (Trx) domain in a single polypeptide. Although NTRC is known to supply reductant for detoxifying hydrogen peroxide in the dark, its other functions are unknown. We now report that NTRC plays a previously unrecognized role in the redox regulation of ADP-glucose pyrophosphorylase (AGPase), a central enzyme of starch synthesis. When supplied NADPH, NTRC activated AGPase in vitro in a redox reaction that required the active site cysteines of both domains of the enzyme. In leaves, AGPase was activated in planta either by light or external feeding of sucrose in the dark. Leaves of an Arabidopsis NTRC KO mutant showed a decrease both in the extent of redox activation of AGPase and in the enhancement of starch synthesis either in the light (by 40-60%) or in the dark after treatment with external sucrose (by almost 100%). The light-dependent activation of AGPase in isolated chloroplasts, by contrast, was unaffected. In nonphotosynthetic tissue (roots), KO of NTRC decreased redox activation of AGPase and starch synthesis in response to light or external sucrose by almost 90%. The results provide biochemical and genetic evidence for a role of NTRC in regulating starch synthesis in response to either light or sucrose. The data also suggest that the Trx domain of NTRC and, to a lesser extent, free Trxs linked to ferredoxin enable amyloplasts of distant sink tissues to sense light used in photosynthesis by leaf chloroplasts and adjust heterotrophic starch synthesis accordingly.
    Proceedings of the National Academy of Sciences 07/2009; 106(24):9908-13. · 9.81 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Extracellular ATP (eATP) has recently been demonstrated to play a crucial role in plant development and growth. To investigate the fate of eATP within the apoplast, we used intact potato (Solanum tuberosum) tuber slices as an experimental system enabling access to the apoplast without interference of cytosolic contamination. (i) Incubation of intact tuber slices with ATP led to the formation of ADP, AMP, adenosine, adenine and ribose, indicating operation of apyrase, 5'-nucleotidase and nucleosidase. (ii) Measurement of apyrase, 5'-nucleotidase and nucleosidase activities in fractionated tuber tissue confirmed the apoplastic localization for apyrase and phosphatase in potato and led to the identification of a novel cell wall-bound adenosine nucleosidase activity. (iii) When intact tuber slices were incubated with saturating concentrations of adenosine, the conversion of adenosine into adenine was much higher than adenosine import into the cell, suggesting a potential bypass of adenosine import. Consistent with this, import of radiolabeled adenine into tuber slices was inhibited when ATP, ADP or AMP were added to the slices. (iv) In wild-type plants, apyrase and adenosine nucleosidase activities were found to be co-regulated, indicating functional linkage of these enzymes in a shared pathway. (v) Moreover, adenosine nucleosidase activity was reduced in transgenic lines with strongly reduced apoplastic apyrase activity. When taken together, these results suggest that a complete ATP salvage pathway is present in the apoplast of plant cells.
    Plant and Cell Physiology 10/2008; 49(10):1572-9. · 4.98 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Heterotrophic carbon metabolism has been demonstrated to be limited by oxygen availability in a variety of plant tissues, which in turn inevitably affects the adenylate status. To study the effect of altering adenylate energy metabolism, without changing the oxygen supply, we expressed a plastidially targeted ATP/ADP hydrolyzing phosphatase (apyrase) in tubers of growing potato (Solanum tuberosum) plants under the control of either inducible or constitutive promoters. Inducible apyrase expression in potato tubers, for a period of 24 h, resulted in a decrease in the ATP-content and the ATP-ADP ratio in the tubers. As revealed by metabolic profiling, this was accompanied by a decrease in the intermediates of sucrose to starch conversion and several plastidially synthesized amino acids, indicating a general depression of tuber metabolism. Constitutive tuber-specific apyrase expression did not lead to a reduction of ATP, but rather a decrease in ADP and an increase in AMP levels. Starch accumulation was strongly inhibited and shifted to the production of amylopectin instead of amylose in these tubers. Furthermore, the levels of almost all amino acids were decreased, although soluble sugars and hexose-Ps were highly abundant. Respiration was elevated in the constitutively expressing lines indicating a compensation for the dramatic increase in ATP hydrolysis. The increase in respiration did not affect the internal oxygen tensions in the tubers. However, the tubers developed a ginger-like phenotype having an elevated surface-volume ratio and a reduced mass per tuber. Decreased posttranslational redox activation of ADP-glucose pyrophosphorylase and a shift in the ratio of soluble starch synthase activity to granule-bound starch synthase activity were found to be partially responsible for the alterations in starch structure and abundance. The activity of alcohol dehydrogenase was decreased and pyruvate decarboxylase was induced, but this was neither reflected by an increase in fermentation products nor in the cellular redox state, indicating that fermentation was not yet induced in the transgenic lines. When taken together the combined results of these studies allow the identification of both short- and long-term adaptation of plant metabolism and development to direct changes in the adenylate status.
    Plant physiology 05/2008; 146(4):1579-98. · 6.56 Impact Factor