ORCID Profile
0000-0003-3883-699X
Current Organisations
Macquarie University
,
University of Hamburg
,
Bruker Daltonics
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Publisher: Elsevier BV
Date: 05-2018
Abstract: Transporting biological s les such as cells or tissues is complicated by the need to maintain integrity and minimise modification and degradation, but this is economically costly as the s les must be shipped in a frozen state. This multi-laboratory study investigated s le variability introduced by non-cooled transport of dried peptide s les for proteomic analysis using mass spectrometry. Human cancer cell tryptic lysates were proteolysed and dried in Australia and shipped by air to Europe and China. S les were measured using label free mass spectrometry on similar LC-MS systems at all three sites. Preparation and analysis of the specimens in this manner resulted in only minor differences in protein identification and showed high quantitative reproducibility amongst the participating laboratories. We examined any impact on peptide chemical modification and report no discrepancies compared to the starting, non-shipped s le. We conclude that transport of non-cooled, dried peptides has negligible effect on s le integrity for downstream LC-MS analysis and therefore represents a cost-effective option to facilitate international proteomic collaborations. Data is available via ProteomeXchange with identifier PXD008160.
Publisher: Informa UK Limited
Date: 05-2016
DOI: 10.2147/BS.S68103
Publisher: Springer Science and Business Media LLC
Date: 24-04-2020
DOI: 10.1038/S41467-020-15738-3
Abstract: The long external filament of bacterial flagella is composed of several thousand copies of a single protein, flagellin. Here, we explore the role played by lysine methylation of flagellin in Salmonella , which requires the methylase FliB. We show that both flagellins of Salmonella enterica serovar Typhimurium, FliC and FljB, are methylated at surface-exposed lysine residues by FliB. A Salmonella Typhimurium mutant deficient in flagellin methylation is outcompeted for gut colonization in a gastroenteritis mouse model, and methylation of flagellin promotes bacterial invasion of epithelial cells in vitro. Lysine methylation increases the surface hydrophobicity of flagellin, and enhances flagella-dependent adhesion of Salmonella to phosphatidylcholine vesicles and epithelial cells. Therefore, posttranslational methylation of flagellin facilitates adhesion of Salmonella Typhimurium to hydrophobic host cell surfaces, and contributes to efficient gut colonization and host infection.
Publisher: Elsevier BV
Date: 02-2016
DOI: 10.1016/J.JPROT.2015.12.015
Abstract: Many diseases are associated with protein species perturbations. A prominent ex le of an established diagnostic marker is the glycated protein species of hemoglobin, termed HbA1c. HbA1c concentration is increased in the blood of diabetes mellitus patients due to their poor control of blood glucose levels resulting in an increased non-enzymatic glycosylation of hemoglobin producing HbA1c. This important diagnostic marker is routinely measured in the blood of diabetes patients. As in the case of HbA1c, protein species can mirror pathophysiological events. Shifts in the levels of protein species can be associated with or even be responsible for disease making them well suited as diagnostic markers. However, only a few protein species are currently used as diagnostic markers in routine clinical chemistry laboratories, despite being widely established in clinical proteomics research. This review provides an overview of the biochemical characteristics associated with protein species as well as ex les of pathophysiological mechanisms, which cause modifications in the protein species composition, thereby emphasizing the importance of screening for protein markers at the species level. Further, we highlight techniques, which are currently utilized for investigating protein species markers in clinical research. The success rate of FDA approved diagnostic protein markers until today is very low compared to the number of published candidate disease markers. It is hypothesized that one important reason is the gene-centric view which is still followed in clinical proteomics: In many investigations proteins are still digested in small peptides thus making it nearly impossible to discriminate between healthy proteins and pathologic proteins causing diseases. Thus this review is focusing on the biochemistry and patho-biochemistry of proteins, is highlighting the need for screening for disease markers on the protein species level and is giving an overview about available techniques.
Publisher: American Chemical Society (ACS)
Date: 17-07-2018
Publisher: Elsevier BV
Date: 02-2016
Publisher: Impact Journals, LLC
Date: 10-11-2017
Publisher: MDPI AG
Date: 19-02-2020
DOI: 10.3390/IJMS21041374
Abstract: Proteomics and genomics discovery experiments generate increasingly large result tables, necessitating more researcher time to convert the biological data into new knowledge. Literature review is an important step in this process and can be tedious for large scale experiments. An informed and strategic decision about which biomolecule targets should be pursued for follow-up experiments thus remains a considerable challenge. To streamline and formalise this process of literature retrieval and analysis of discovery based ‘omics data and as a decision-facilitating support tool for follow-up experiments we present OmixLitMiner, a package written in the computational language R. The tool automates the retrieval of literature from PubMed based on UniProt protein identifiers, gene names and their synonyms, combined with user defined contextual keyword search (i.e., gene ontology based). The search strategy is programmed to allow either strict or more lenient literature retrieval and the outputs are assigned to three categories describing how well characterized a regulated gene or protein is. The category helps to meet a decision, regarding which gene rotein follow-up experiments may be performed for gaining new knowledge and to exclude following already known biomarkers. We demonstrate the tool’s usefulness in this retrospective study assessing three cancer proteomics and one cancer genomics publication. Using the tool, we were able to corroborate most of the decisions in these papers as well as detect additional biomolecule leads that may be valuable for future research.
Publisher: Public Library of Science (PLoS)
Date: 10-06-2021
DOI: 10.1371/JOURNAL.PONE.0253084
Abstract: Rickettsioses are neglected and emerging potentially fatal febrile diseases that are caused by obligate intracellular bacteria, rickettsiae. Rickettsia ( R .) typhi and R . prowazekii constitute the typhus group (TG) of rickettsiae and are the causative agents of endemic and epidemic typhus, respectively. We recently generated a monoclonal antibody (BNI52) against R . typhi . Characterization of BNI52 revealed that it specifically recognizes TG rickettsiae but not the members of the spotted fever group (SFG) rickettsiae. We further show that BNI52 binds to protein fragments of ±30 kDa that are exposed on the bacterial surface and also present in the periplasmic space. These protein fragments apparently derive from the cytosolic GroEL protein of R . typhi and are also recognized by antibodies in the sera from patients and infected mice. Furthermore, BNI52 opsonizes the bacteria for the uptake by antigen presenting cells (APC), indicating a contribution of GroEL-specific antibodies to protective immunity. Finally, it is interesting that the GroEL protein belongs to 32 proteins that are differentially downregulated by R . typhi after passage through immunodeficient BALB/c CB17 SCID mice. This could be a hint that the rickettsia GroEL protein may have immunomodulatory properties as shown for the homologous protein from several other bacteria, too. Overall, the results of this study provide evidence that GroEL represents an immunodominant antigen of TG rickettsiae that is recognized by the humoral immune response against these pathogens and that may be interesting as a vaccine candidate. Apart from that, the BNI52 antibody represents a new tool for specific detection of TG rickettsiae in various diagnostic and experimental setups.
Publisher: Elsevier BV
Date: 09-2020
Publisher: Springer Science and Business Media LLC
Date: 10-2018
DOI: 10.1038/S12276-018-0157-3
Abstract: Cosmc is ubiquitously expressed and acts as a specific molecular chaperone assisting the folding and stability of core 1 synthase. Thus, it plays a crucial role in the biosynthesis of O-linked glycosylation of proteins. Here, we show that ablation of Cosmc in the exocrine pancreas of mice causes expression of truncated O-glycans (Tn antigen), resulting in exocrine pancreatic insufficiency with decreased activities of digestive enzymes and diabetes. To understand the molecular causes of the pleiotropic phenotype, we used Vicia villosa agglutinin to enrich Tn antigen-modified proteins from Cosmc-KO pancreatic lysates and performed a proteomic analysis. Interestingly, a variety of proteins were identified, of which bile salt-activated lipase (also denoted carboxyl-ester lipase, Cel) was the most abundant. In humans, frameshift mutations in CEL cause maturity-onset diabetes of the young type 8 (MODY8), a monogenic syndrome of diabetes and pancreatic exocrine dysfunction. Here, we provide data suggesting that differentially O-glycosylated Cel could negatively affect beta cell function. Taken together, our findings demonstrate the importance of correct O-glycan formation for normal exocrine and endocrine pancreatic function, implying that aberrant O-glycans might be relevant for pathogenic mechanisms of the pancreas.
No related grants have been discovered for Pascal Steffen.