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Y ersinia enterocolitica type III secretion injectisomes form regularly spaced clusters, which incorporate new machines upon activation
Author(s) -
Kudryashev Mikhail,
Diepold Andreas,
Amstutz Marlise,
Armitage Judith P.,
Stahlberg Henning,
Cornelis Guy R.
Publication year - 2015
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.12908
Subject(s) - secretion , biology , fluorescence , microbiology and biotechnology , fluorescence microscope , biophysics , cluster (spacecraft) , bacteria , multiprotein complex , effector , biochemistry , physics , genetics , optics , computer science , programming language , gene
Summary Bacterial type III secretion systems or injectisomes are multiprotein complexes directly transporting bacterial effector proteins into eukaryotic host cells. To investigate the distribution of injectisomes in the bacterium and the influence of activation of the system on that distribution, we combined in vivo fluorescent imaging and high‐resolution in situ visualization of Y ersinia enterocolitica injectisomes by cryo‐electron tomography. Fluorescence microscopy showed the injectisomes as regularly distributed spots around the bacterial cell. Under secreting conditions (absence of Ca 2+ ), the intensity of single spots significantly increased compared with non‐secreting conditions (presence of Ca 2+ ), in line with an overall up‐regulation of expression levels of all components. Single injectisomes observed by cryo‐electron tomography tended to cluster at distances less than 100 nm, suggesting that the observed fluorescent spots correspond to evenly distributed clusters of injectisomes, rather than single injectisomes. The up‐regulation of injectisome components led to an increase in the number of injectisomes per cluster rather than the formation of new clusters. We suggest that injectisome clustering may allow more effective secretion into the host cells.