title: DNA and origin region segregation are not affected by the transition from rod to sphere after inhibition of Escherichia coli MreB by A22.
abstract: The bacterial actin homologue MreB forms a helix underneath the cytoplasmic membrane and was shown to be essential in the morphogenesis of the rod-shaped cells. Additionally, MreB was implicated to be involved in DNA segregation. However, in our hands the mreBCD deletion strain (PA340-678) grew without apparent DNA segregation defect, suggesting that the reported chromosome segregation inhibition could be caused by a temporarily effect of MreB inhibition or depletion. To assess the involvement of MreB in DNA segregation during the transition from rod to sphere, we compared the effect of A22 and the PBP2 inhibitor mecillinam on the percentage of cells with segregated nucleoids and the number of oriC foci in wild-type Escherichia coli cells. Cells became spherical in the same time window during both treatments and we could not detect any difference in the chromosome or oriC segregation between these two treatments. Additionally, flow cytometric analyses showed that A22 and mecillinam treatment gave essentially the same chromosome segregation pattern. We conclude that MreB is not directly involved in DNA segregation of E. coli.
authors.affiliation: Swammerdam Institute for Life Sciences, Kruislaan 316, 1098 SM Amsterdam, PO Box 194062, 1090 GB Amsterdam, The Netherlands.
authors.forename: Aneta
authors.initials: A
authors.lastname: Karczmarek
authors.forename: Rocío
authors.initials: R
authors.lastname: Martínez-Arteaga
authors.forename: Rocío Martínez-Arteaga
authors.initials: RM
authors.lastname: Baselga
authors.forename: Svetlana
authors.initials: S
authors.lastname: Alexeeva
authors.forename: Flemming G
authors.initials: FG
authors.lastname: Hansen
authors.forename: Miguel
authors.initials: M
authors.lastname: Vicente
authors.forename: Nanne
authors.initials: N
authors.lastname: Nanninga
authors.forename: Tanneke
authors.initials: T
authors.lastname: den Blaauwen
mesh_terms: D000560:Amdinocillin / Q000494:pharmacology; D020090:Chromosome Segregation; D004261:DNA Replication; D004269:DNA, Bacterial / Q000235:genetics*; D048168:Escherichia coli K12 / Q000166:cytology* / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D051738:Origin Recognition Complex / Q000235:genetics*
chemical_list: D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; C114650:OriC chromosomal replication origin; D051738:Origin Recognition Complex; C078473:MreB protein, E coli; D000560:Amdinocillin