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Distinct constrictive processes, separated in time and space,divide Caulobacter inner and outer membranes

Journal Article · · Journal of Bacteriology
Cryo-electron microscope tomography (cryoEM) and a fluorescence loss in photobleaching (FLIP) assay were used to characterize progression of the terminal stages of Caulobacter crescentus cell division. Tomographic cryoEM images of the cell division site show separate constrictive processes closing first the inner, and then the outer, membrane in a manner distinctly different from septum-forming bacteria. The smallest observed pre-fission constrictions were 60 nm for both the inner and outer membrane. FLIP experiments had previously shown cytoplasmic compartmentalization, when cytoplasmic proteins can no longer diffuse between the two nascent progeny cell compartments, occurring 18 min before daughter cell separation in a 135 min cell cycle. Here, we used FLIP experiments with membrane-bound and periplasmic fluorescent proteins to show that (1) periplasmic compartmentalization occurs after cytoplasmic compartmentalization, consistent with the cryoEM observations, and (2) inner membrane and periplasmic proteins can diffuse past the FtsZ constriction site, indicating that the cell division machinery does not block membrane diffusion.
Research Organization:
Ernest Orlando Lawrence Berkeley NationalLaboratory, Berkeley, CA (US)
Sponsoring Organization:
USDOE Director. Office of Science. Office of Biological andEnvironmental Research. Contracts DE-AC03-76SF00098 and DE-FG02-04ER63777and DE-FG03-01ER63219-A001; National Institutes of Health Grant F32G067472
DOE Contract Number:
AC02-05CH11231
OSTI ID:
862180
Report Number(s):
LBNL--58281; BnR: KP1102010
Journal Information:
Journal of Bacteriology, Journal Name: Journal of Bacteriology Journal Issue: 20 Vol. 187; ISSN JOBAAY; ISSN 0021-9193
Country of Publication:
United States
Language:
English