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The article studies the comparison of receptor-defined breast cancer proportions in women across Southern Africa. The study evaluated estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) statuses in two Southern African countries with routine diagnostic immunohistochemistry. The study showed that ER breast cancer dominates in all Southern African races with black women having an excess of aggressive subtypes.

Summary: Sub-Saharan Africa is a common destination for occupational travellers from South Africa. Adequate preventive measures require timeous medical consultation before travel. A secondary analysis of datasets of over 8000 occupational travellers who visited travel clinics in South Africa indicated that 82% were travelling to African countries and over 50% consulted less than a week before travel. For the 70% who consult less than 10 days before departure, yellow fever certificates issued at consultation would not be valid for entry to endemic countries, although they may be protected from contracting yellow fever. The ‘last minute’ travel medicine consultation appears to be more common in South Africa than in Europe and North America. This may preclude South African health professionals from providing occupational travellers adequate disease prevention, particularly against vaccine-preventable infectious diseases. [Copyright &y& Elsevier]

Introduction: Sub Saharan Africa, a very high-risk destination for travellers, is an important destination for South African workers. The concomitant occupational exposure to infectious diseases raises concern about the adequate risk-related preparation of business travellers, particularly those moving to remote areas. Occupational health practitioners in South Africa are concerned about expatriates whose ‘last-minute’ consultation pattern may preclude adequate disease prevention and appropriate preparation for travel. The South African Society of Travel Medicine established a national sentinel surveillance system and, with the National Institute for Occupational Health, investigated the pre-travel consultation patterns in business travellers. Methods: A retrospective study was conducted on records of 20000 travellers attending 24 sentinel general and travel medicine practices in main South African centres from January 2005 to December 2006. Reason for travel, destination, and the time between consultation and departure were collated. Data were analysed using STATA. Results: Business travellers comprised 42% of the travellers consulting clinics and had a mean ‘consultation to departure’ period of 15.2 days. Over half the business travellers (54%) consult less than a week before departure, while 92% consult less than a month before departure. Other countries in Africa are the destination for 73% of business travellers. Discussion: This is the first national surveillance of South African corporate and leisure travellers seeking travel advice. Since Africa is the destination for most business travellers consulting travel medicine clinics in South Africa, the period of consultation prior to departure is of particular concern with regard to malaria prophylaxis and completion of multiple dose vaccine schedules. The findings of this sentinel surveillance indicate the need for detailed comparison of time to departure with vaccines and malaria prophylaxis; for targeted advice to the corporate industries deploying employees in Africa; and to define accelerated schedules to maximise protection for the ‘last-minute’ business traveller. [Copyright &y& Elsevier]

Identification of interactions between proteins and natural products or similar active small molecules is crucial for understanding of their mechanism of action on a molecular level. To search elusive, often labile, and low-abundant conjugates between proteins and active compounds, chemical proteomics introduces a feasible strategy that allows to enrich and detect these conjugates. Recent advances in mass spectrometry techniques and search algorithms provide unprecedented depth of proteome coverage and the possibility to detect desired modified peptides with high sensitivity. The chemical 'linker' connecting an active compound-protein conjugate with a detection tag is the critical component of all chemical proteomic workflows. In this review, we discuss the properties and applications of different chemical proteomics linkers with special focus on their fragmentation releasing diagnostic ions and how these may improve the confidence in identified active compound-peptide conjugates. The application of advanced search options improves the identification rates and may help to identify otherwise difficult to find interactions between active compounds and proteins, which may result from unperturbed conditions, and thus are of high physiological relevance., (Copyright © 2024, Wiest and Kielkowski.)

Tubulin detyrosination-tyrosination cycle regulates the stability of microtubules. With respect to α-tubulins, the tyrosination level is maintained by a single tubulin-tyrosine ligase (TTL). However, the precise dynamics and tubulin isoforms which undergo (de)tyrosination in neurons are unknown. Here, we exploit the substrate promiscuity of the TTL to introduce an O-propargyl-l-tyrosine to neuroblastoma cells and neurons. Mass spectrometry-based chemical proteomics in neuroblastoma cells using the O-propargyl-l-tyrosine probe revealed previously discussed tyrosination of TUBA4A, MAPRE1, and other non-tubulin proteins. This finding was further corroborated in differentiating neurons. Together we present the method for tubulin tyrosination profiling in living cells. Our results show that detyrosination-tyrosination is not restricted to α-tubulins with coded C-terminal tyrosine and is thus involved in fine-tuning of the tubulin and non-tubulin proteins during neuronal differentiation., (© 2022 The Authors. ChemBioChem published by Wiley-VCH GmbH.)

The identification and quantification of modified peptides are critical for the functional characterization of post-translational protein modifications (PTMs) to elucidate their biological function. Nowadays, quantitative mass spectrometry coupled with various bioinformatic pipelines has been successfully used for the determination of a wide range of PTMs. However, direct characterization of low abundant protein PTMs in bottom-up proteomic workflow remains challenging. Here, we present the synthesis and evaluation of tandem mass spectrometry tags (TMT) which are introduced via click-chemistry into peptides bearing alkyne handles. The fragmentation properties of the two mass tags were validated and used for screening in a model system and analysis of AMPylated proteins. The presented tags provide a valuable tool for diagnostic peak generation to increase confidence in the identification of modified peptides and potentially for direct peptide-PTM quantification from various experimental conditions., (© 2022 The Authors. Journal of Mass Spectrometry published by John Wiley & Sons Ltd.)

Protein AMPylation is a posttranslational modification with an emerging role in neurodevelopment. In metazoans two highly conserved protein AMP-transferases together with a diverse group of AMPylated proteins have been identified using chemical proteomics and biochemical techniques. However, the function of AMPylation remains largely unknown. Particularly problematic is the localization of thus far identified AMPylated proteins and putative AMP-transferases. We show that protein AMPylation is likely a posttranslational modification of luminal lysosomal proteins characteristic in differentiating neurons. Through a combination of chemical proteomics, gel-based separation of modified and unmodified proteins, and an activity assay, we determine that the modified, lysosomal soluble form of exonuclease PLD3 increases dramatically during neuronal maturation and that AMPylation correlates with its catalytic activity. Together, our findings indicate that AMPylation is a so far unknown lysosomal posttranslational modification connected to neuronal differentiation and it may provide a molecular rationale behind lysosomal storage diseases and neurodegeneration., Competing Interests: The authors declare no competing interests., (© 2021 The Author(s).)

Canonically, tRNA synthetases charge tRNA. However, the lysyl-tRNA synthetase paralog EpmA catalyzes the attachment of (R)-β-lysine to the ε-amino group of lysine 34 of the translation elongation factor P (EF-P) in Escherichia coli. This modification is essential for EF-P-mediated translational rescue of ribosomes stalled at consecutive prolines. In this study, we determined the kinetics of EpmA and its variant EpmA_A298G to catalyze the post-translational modification of K34 in EF-P with eight noncanonical substrates. In addition, acetylated EF-P was generated using an amber suppression system. The impact of these synthetically modified EF-P variants on in vitro translation of a polyproline-containing NanoLuc luciferase reporter was analyzed. Our results show that natural (R)-β-lysylation was more effective in rescuing stalled ribosomes than any other synthetic modification tested. Thus, our work not only provides new biochemical insights into the function of EF-P, but also opens a new route to post-translationally modify proteins using EpmA., (© 2020 The Authors. The FEBS Journal published by John Wiley & Sons Ltd on behalf of Federation of European Biochemical Societies.)

Protein post-translational modifications (PTMs) are implicated in numerous physiological processes and significantly contribute to complex regulatory networks of protein functions. Recently, a protein PTM called AMPylation was found to play a role in modulation of neurodevelopment and neurodegeneration. Combination of biochemical and chemical proteomic studies has uncovered the prevalence of this PTM in regulation of diverse metabolic pathways. In metazoans, thus far two protein AMP transferases have been identified to introduce AMPylation: FICD and SELO. These two proteins were found to be involved in unfolded protein response and redox homeostasis on the cellular level and in the case of FICD to adjust the development of glial cells and neurons in Drosophila and cerebral organoids, respectively. Together with findings on AMPylation and its association with toxic protein aggregation, we summarize in this Perspective the knowledge and putative future directions of protein AMPylation research., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Conjugation of proteins to AMP (AMPylation) is a prevalent post-translational modification (PTM) in human cells, involved in the regulation of unfolded protein response and neural development. Here we present a tailored pronucleotide probe suitable for in situ imaging and chemical proteomics profiling of AMPylated proteins. Using straightforward strain-promoted azide-alkyne click chemistry, the probe provides stable fluorescence labelling in living cells., (© 2020 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.)

Caseinolytic protease P (ClpP) is the proteolytic component of the ClpXP protein degradation complex. Eukaryotic ClpP was recently found to act within the mitochondria-specific unfolded protein response (UPR mt ). However, its detailed function and dedicated regulation remain largely unexplored. A small molecule (D9) acts as a potent and species-selective activator of human ClpP (hClpP) by mimicking the natural chaperone ClpX. Structure-activity relationship studies highlight the importance of a halogenated benzyl motif within D9 that interacts with a unique aromatic amino acid network in hClpP. Mutational and structural studies suggest that this YYW motif tightly controls hClpP activity and regulates substrate turnover by interaction with cognate ligands. This signature motif is unique to ClpP from higher organisms and does not exist in tested bacterial homologues, allowing a species-selective analysis. Thus, D9 is a versatile tool to analyze mechanistic features of hClpP., (© 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

New types of double-headed 2'-deoxycytidine 5'-O-triphosphates (dC(XC)TPs) bearing another cytosine or 5-fluorocytosine linked through a flexible propargyl, homopropargyl or pent-1-ynyl linker to position 5 were prepared by the aqueous Sonogashira cross-coupling reactions of 5-iodo-dCTP with the corresponding (fluoro)cytosine-alkynes. The modified dC(XC)TPs were good substrates for DNA polymerases and were used for enzymatic synthesis of cytosine-functionalized DNA by primer extension or PCR. The cytosine- or fluorocytosine-linked DNA probes did not significantly inhibit DNA methyltransferases and did not cross-link to these proteins., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

A series of 7-substituted 7-deazaadenine and 5-substituted cytosine 2'-deoxyribonucleoside triphosphates (dNTPs) were tested for their competitive incorporations (in the presence of dATP and dCTP) into DNA by several DNA polymerases by using analysis based on cleavage by restriction endonucleases. 7-Aryl-7-deazaadenine dNTPs were more efficient substrates than dATP because of their higher affinity for the active site of the enzyme, as proved by kinetic measurements and calculations., (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Protecting group chemistry meets molecular biology: Chemically modified dATP carrying a bulky triethylsilylethynyl group was used in a PCR-based synthesis of a gene internally protected against cleavage by restriction endonucleases. The unmodified flanking regions were cleaved for cloning into a plasmid which was replicated by E. coli, and used for protein production., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)