title: Bacterial nucleoid dynamics: oxidative stress response in Staphylococcus aureus.
abstract: A single-molecule-imaging technique, atomic force microscopy (AFM) was applied to the analyses of the genome architecture of Staphylococcus aureus. The staphylococcal cells on a cover glass were subjected to a mild lysis procedure that had maintained the fundamental structural units in Escherichia coli. The nucleoids were found to consist of fibrous structures with diameters of 80 and 40 nm. This feature was shared with the E. coli nucleoid. However, whereas the E. coli nucleoid dynamically changed its structure to a highly compacted one towards the stationary phase, the S. aureus nucleoid never underwent such a tight compaction under a normal growth condition. Bioinformatic analysis suggested that this was attributable to the lack of IHF that regulate the expression of a nucleoid protein, Dps, required for nucleoid compaction in E. coli. On the other hand, under oxidative conditions, MrgA (a staphylococcal Dps homolog) was over-expressed and a drastic compaction of the nucleoid was detected. A knock-out mutant of the gene encoding the transcription factor (perR) constitutively expressed mrgA, and its nucleoid was compacted without the oxidative stresses. The regulatory mechanisms of Dps/MrgA expression and their biological significance were postulated in relation to the nucleoid compaction.
authors.affiliation: Institute of Basic Medical Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tennoh-dai, Tsukuba 305-8575, Japan. morikawa@sakura.cc.tsukuba.ac.jp
authors.forename: Kazuya
authors.initials: K
authors.lastname: Morikawa
authors.forename: Ryosuke L
authors.initials: RL
authors.lastname: Ohniwa
authors.forename: Joongbaek
authors.initials: J
authors.lastname: Kim
authors.forename: Atsushi
authors.initials: A
authors.lastname: Maruyama
authors.forename: Toshiko
authors.initials: T
authors.lastname: Ohta
authors.forename: Kunio
authors.initials: K
authors.lastname: Takeyasu
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D022003:Cell Nucleus Structures / Q000502:physiology* / Q000648:ultrastructure; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000737:chemistry / Q000502:physiology; D018625:Microscopy, Atomic Force / Q000379:methods; D018384:Oxidative Stress / Q000502:physiology*; D010802:Phylogeny; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D012680:Sensitivity and Specificity; D013211:Staphylococcus aureus / Q000737:chemistry / Q000502:physiology* / Q000648:ultrastructure; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; C083911:DPS protein, Bacteria; D012097:Repressor Proteins; D014157:Transcription Factors; C122138:peroxide repressor proteins