Cell size and nucleoid organization of engineered Escherichia coli cells with a reduced genome.
The minimization of a genome is necessary to identify experimentally the minimal gene set that contains only those genes that are essential and sufficient to sustain a functioning cell. Recent developments in genetic techniques have made it possible to generate bacteria with a markedly reduced genome. We developed a simple system for formation of markerless chromosomal deletions, and constructed and characterized a series of large-scale chromosomal deletion mutants of Escherichia coli that lack between 2.4 and 29.7% of the parental chromosome. Combining deletion mutations changes cell length and width, and the mutant cells with larger deletions were even longer and wider than the parental cells. The nucleoid organization of the mutants is also changed: the nucleoids occur as multiple small nucleoids and are localized peripherally near the envelope. Inhibition of translation causes them to condense into one or two packed nucleoids, suggesting that the coupling of transcription and translation of membrane proteins peripherally localizes chromosomes. Because these phenotypes are similar to those of spherical cells, those may be a consequence of the morphological change. Based on the nucleoid localization observed with these mutants, we discuss the cellular nucleoid dynamics.
Hashimoto
Masayuki
M
Department of Biology, Graduate School of Science, Tokyo Metropolitan University, Minamiohsawa, Hachioji, Tokyo, Japan.
Ichimura
Toshiharu
T
Mizoguchi
Hiroshi
H
Tanaka
Kimie
K
Fujimitsu
Kazuyuki
K
Keyamura
Kenji
K
Ote
Tomotake
T
Yamakawa
Takehiro
T
Yamazaki
Yukiko
Y
Mori
Hideo
H
Katayama
Tsutomu
T
Kato
Jun-ichi
J
D002467:Cell Nucleus; D002872:Chromosome Deletion; D004926:Escherichia coli / Q000166:cytology* / Q000235:genetics* / Q000254:growth & development; D029968:Escherichia coli Proteins / Q000096:biosynthesis / Q000502:physiology; D005456:Fluorescent Dyes / Q000494:pharmacology; D005798:Genes, Bacterial; D016680:Genome, Bacterial; D007211:Indoles / Q000494:pharmacology; D008853:Microscopy; D014176:Protein Biosynthesis; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D013194:Staining and Labeling; D014158:Transcription, Genetic
D029968:Escherichia coli Proteins; D005456:Fluorescent Dyes; D007211:Indoles; D011500:Protein Synthesis Inhibitors; C007293:DAPI