Chromosome replication and segregation govern the biogenesis and inheritance of inorganic polyphosphate granules
+ Affiliations
- Fred Chang, Monitoring Editor
+ Affiliations
- Submitted April 5, 2013.
- Revised August 15, 2013.
- Accepted August 19, 2013.
Abstract
Prokaryotes and eukaryotes synthesize long
chains of orthophosphate, known as polyphosphate (polyP), which form
dense granules
within the cell. PolyP regulates myriad cellular
functions and is often localized to specific subcellular addresses
through
mechanisms that remain undefined. In this study, we
present a molecular-level analysis of polyP subcellular localization in
the model bacterium, Caulobacter crescentus.
We demonstrate that biogenesis and localization of polyP is controlled
as a function of the cell cycle, which ensures regular
partitioning of granules between mother and
daughter. The enzyme polyphosphate kinase 1 (Ppk1) is required for
granule production,
colocalizes with granules, and dynamically
localizes to the sites of new granule synthesis in nascent daughter
cells. Localization
of Ppk1 within the cell requires an intact
catalytic active site and a short, positively-charged tail at the
C-terminus of
the protein. The processes of chromosome
replication and segregation govern both the number and position of
Ppk1/polyP complexes
within the cell. We propose a multi-step model
whereby the chromosome establishes sites of polyP coalescence, which
recruit
Ppk1 to promote the in situ synthesis of large
granules. These findings underscore the importance of both chromosome
dynamics
and discrete protein localization as organizing
factors in bacterial cell biology.
Footnotes
- ↵‡Address correspondence to: Sean Crosson (scrosson@uchicago.edu).
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