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J Bacteriol. 2019 Apr 29. pii: JB.00724-18. doi: 10.1128/JB.00724-18. [Epub ahead of print]

A genome-wide Helicobacter pylori morphology screen uncovers a membrane spanning helical cell shape complex.

Author information

1
Division of Human Biology, Fred Hutchinson Cancer Research Center, Seattle WA, USA.
2
Molecular and Cellular Biology Ph.D. Program, University of Washington, USA.
3
Department of Microbiology, University of Washington School of Medicine, Seattle, WA, USA.
4
BD Biosciences, Seattle, WA, USA.
5
Division of Science and Mathematics, University of Minnesota, Morris, MN, USA.
6
Centre for Bacterial Cell Biology, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, UK.
7
Division of Human Biology, Fred Hutchinson Cancer Research Center, Seattle WA, USA nsalama@fredhutch.org.

Abstract

Evident in its name, the gastric pathogen Helicobacter pylori has helical cell morphology which facilitates efficient colonization of the human stomach. An improved light focusing strategy allowed us to robustly distinguish even subtle perturbations of H. pylori cell morphology by deviations in light scattering properties measured by flow cytometry. Profiling of an arrayed genome-wide deletion library identified 28 genes that influence different aspects of cell shape including properties of the helix, cell length or width, cell filament formation, cell shape heterogeneity and cell branching. Included in this mutant collection were two that failed to form any helical cells, a soluble lytic transglycosylase and a previously uncharacterized putative multi-pass inner membrane protein HPG27_0728, renamed Csd7. A combination of cell fractionation, mutational and immunoprecipitation experiments show that Csd7 and Csd2 collaborate to stabilize the Csd1 peptidoglycan (PG) endopeptidase. Thus, both csd2 and csd7 mutants show the same enhancement of PG tetra-pentapeptide crosslinking as csd1 mutants. Csd7 also links Csd1 with the bactofilin CcmA via protein-protein interactions. Although Csd1 is stable in ccmA mutants, these mutants show altered PG tetra-pentapeptide crosslinking, suggesting that Csd7 may directly or indirectly activate as well as stabilize Csd1. These data begin to illuminate a highly orchestrated program to regulate PG modifications that promote helical shape, which includes nine non-essential, non-redundant genes required for helical shape and 26 additional genes that further modify H. pylori's cell morphology.ImportanceThe stomach ulcer and cancer-causing pathogen Helicobacter pylori has helical cell shape which facilitates stomach infection. Using light scattering to measure perturbations of cell morphology, we identified 28 genes that influence different aspects of cell shape. A mutant in a previously uncharacterized protein renamed Csd7 failed to form any helical cells. Biochemical analyses showed that Csd7 collaborates with other proteins to stabilize the cell wall degrading enzyme Csd1. Csd7 also links Csd1 with a putative filament forming protein via protein-protein interactions. These data suggest that helical cell shape arises from a a highly orchestrated program to regulate cell wall modifications. Targeting of this helical cell shape promoting program could offer new ways to block infectivity of this important human pathogen.

PMID:
31036730
DOI:
10.1128/JB.00724-18

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