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Sopelniak, K.

Publications and source records attributed to Sopelniak, K..

2 recordsLinked to original sources

Phagocytic podosomes enable efficient uptake of Candida auris by primary human macrophages

The yeast Candida auris is an emerging pathogen of steadily increasing importance. Understanding the molecular mechanisms of C. auris uptake and intracellular processing by immune cells such as macrophages is thus critical for counteracting the spreading of respective infections. Here, we show that phagocytosis of C. auris cells by primary human macrophages involves the formation of dot-like F-actin-rich structures at C. auris-containing phagosomes that we characterize as phagocytic podosomes. We analyse the composition, architecture, and dynamics of these structures, showing that they constitute a specific and highly dynamic adaptation of the phagocytic actin network of macrophages. We also show that disruption of phagocytic podosomes is associated with reduced internalization of C. auris cells and delayed maturation of respective phagosomes. Our data provide novel insights into the uptake mechanism and cytoskeletal rearrangements upon internalization of Candida by immune cells, while also challenging the dogma of a generally uniform and continuous actin network within phagocytic cups. At the same time, we identify C. auris as the first pathophysiologically relevant target whose internalization involves the formation of phagocytic podosomes.

cell biology↗

Discovery of a new evolutionarily conserved short linear F-actin binding motif

Regulation of the actin cytoskeleton by actin binding proteins (ABPs) is essential for cellular homeostasis, and the mode of actin binding determines the activity of ABPs. Here, we discovered a novel "Short linear F-actin binding motif (SFM)" on the basis of the cryo-EM structure of the ITPKA-F-actin complex. We developed the computational pipeline SLiMFold, which identified 103 human SFM containing-proteins exhibiting diverse cellular functions. The SFM probably developed ex nihilo and remained conserved in eukaryotes, with a binding affinity to F-actin ranging from 13 to 89 {micro}M. Furthermore, we uncovered the essential amino acids of this SFM for F-actin binding and affinity modulation. Together, the SFM seems to serve as a low affinity anchor to target proteins to F-actin, in order to connect the regulation of actin dynamics with broad cellular functions. These findings will shed new light on the role of a wide variety of proteins.

biochemistry↗