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Essential gene deletions producing gigantic bacteria

To characterize the consequences of eliminating essential functions needed for peptidoglycan synthesis, we generated deletion mutations of Acinetobacter baylyi by natural transformation and visualized the resulting microcolonies of dead cells. We found that loss of genes required for peptidoglycan p...

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Autores principales: Bailey, Jeannie, Cass, Julie, Gasper, Joe, Ngo, Ngoc-Diep, Wiggins, Paul, Manoil, Colin
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Public Library of Science 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6586353/
https://www.ncbi.nlm.nih.gov/pubmed/31181062
http://dx.doi.org/10.1371/journal.pgen.1008195
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author Bailey, Jeannie
Cass, Julie
Gasper, Joe
Ngo, Ngoc-Diep
Wiggins, Paul
Manoil, Colin
author_facet Bailey, Jeannie
Cass, Julie
Gasper, Joe
Ngo, Ngoc-Diep
Wiggins, Paul
Manoil, Colin
author_sort Bailey, Jeannie
collection PubMed
description To characterize the consequences of eliminating essential functions needed for peptidoglycan synthesis, we generated deletion mutations of Acinetobacter baylyi by natural transformation and visualized the resulting microcolonies of dead cells. We found that loss of genes required for peptidoglycan precursor synthesis or polymerization led to the formation of polymorphic giant cells with diameters that could exceed ten times normal. Treatment with antibiotics targeting early or late steps of peptidoglycan synthesis also produced giant cells. The giant cells eventually lysed, although they were partially stabilized by osmotic protection. Genome-scale transposon mutant screening (Tn-seq) identified mutations that blocked or accelerated giant cell formation. Among the mutations that blocked the process were those inactivating a function predicted to cleave murein glycan chains (the MltD murein lytic transglycosylase), suggesting that giant cell formation requires MltD hydrolysis of existing peptidoglycan. Among the mutations that accelerated giant cell formation after ß-lactam treatment were those inactivating an enzyme that produces unusual 3->3 peptide cross-links in peptidoglycan (the LdtG L,D-transpeptidase). The mutations may weaken the sacculus and make it more vulnerable to further disruption. Although the study focused on A. baylyi, we found that a pathogenic relative (A. baumannii) also produced giant cells with genetic dependencies overlapping those of A. baylyi. Overall, the analysis defines a genetic pathway for giant cell formation conserved in Acinetobacter species in which independent initiating branches converge to create the unusual cells.
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spelling pubmed-65863532019-06-28 Essential gene deletions producing gigantic bacteria Bailey, Jeannie Cass, Julie Gasper, Joe Ngo, Ngoc-Diep Wiggins, Paul Manoil, Colin PLoS Genet Research Article To characterize the consequences of eliminating essential functions needed for peptidoglycan synthesis, we generated deletion mutations of Acinetobacter baylyi by natural transformation and visualized the resulting microcolonies of dead cells. We found that loss of genes required for peptidoglycan precursor synthesis or polymerization led to the formation of polymorphic giant cells with diameters that could exceed ten times normal. Treatment with antibiotics targeting early or late steps of peptidoglycan synthesis also produced giant cells. The giant cells eventually lysed, although they were partially stabilized by osmotic protection. Genome-scale transposon mutant screening (Tn-seq) identified mutations that blocked or accelerated giant cell formation. Among the mutations that blocked the process were those inactivating a function predicted to cleave murein glycan chains (the MltD murein lytic transglycosylase), suggesting that giant cell formation requires MltD hydrolysis of existing peptidoglycan. Among the mutations that accelerated giant cell formation after ß-lactam treatment were those inactivating an enzyme that produces unusual 3->3 peptide cross-links in peptidoglycan (the LdtG L,D-transpeptidase). The mutations may weaken the sacculus and make it more vulnerable to further disruption. Although the study focused on A. baylyi, we found that a pathogenic relative (A. baumannii) also produced giant cells with genetic dependencies overlapping those of A. baylyi. Overall, the analysis defines a genetic pathway for giant cell formation conserved in Acinetobacter species in which independent initiating branches converge to create the unusual cells. Public Library of Science 2019-06-10 /pmc/articles/PMC6586353/ /pubmed/31181062 http://dx.doi.org/10.1371/journal.pgen.1008195 Text en © 2019 Bailey et al http://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
spellingShingle Research Article
Bailey, Jeannie
Cass, Julie
Gasper, Joe
Ngo, Ngoc-Diep
Wiggins, Paul
Manoil, Colin
Essential gene deletions producing gigantic bacteria
title Essential gene deletions producing gigantic bacteria
title_full Essential gene deletions producing gigantic bacteria
title_fullStr Essential gene deletions producing gigantic bacteria
title_full_unstemmed Essential gene deletions producing gigantic bacteria
title_short Essential gene deletions producing gigantic bacteria
title_sort essential gene deletions producing gigantic bacteria
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6586353/
https://www.ncbi.nlm.nih.gov/pubmed/31181062
http://dx.doi.org/10.1371/journal.pgen.1008195
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