title: In vivo architecture and action of bacterial structural maintenance of chromosome proteins.
abstract: SMC (structural maintenance of chromosome) proteins act ubiquitously in chromosome processing. In Escherichia coli, the SMC complex MukBEF plays roles in chromosome segregation and organization. We used single-molecule millisecond multicolor fluorescence microscopy of live bacteria to reveal that a dimer of dimeric fluorescent MukBEF molecules acts as the minimal functional unit. On average, 8 to 10 of these complexes accumulated as "spots" in one to three discrete chromosome-associated regions of the cell, where they formed higher-order structures. Functional MukBEF within spots exchanged with freely diffusing complexes at a rate of one complex about every 50 seconds in reactions requiring adenosine triphosphate (ATP) hydrolysis. Thus, by functioning in pairs, MukBEF complexes may undergo multiple cycles of ATP hydrolysis without being released from DNA, analogous to the behavior of well-characterized molecular motors.
authors.affiliation: Department of Biochemistry, University of Oxford, UK.
authors.forename: Anjana
authors.initials: A
authors.lastname: Badrinarayanan
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Reyes-Lamothe
authors.forename: Stephan
authors.initials: S
authors.lastname: Uphoff
authors.forename: Mark C
authors.initials: MC
authors.lastname: Leake
authors.forename: David J
authors.initials: DJ
authors.lastname: Sherratt
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D002868:Chromosomal Proteins, Non-Histone / Q000737:chemistry / Q000378:metabolism*; D002876:Chromosomes, Bacterial / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure*; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000378:metabolism*; D005453:Fluorescence; D006868:Hydrolysis; D008856:Microscopy, Fluorescence; D055503:Protein Multimerization; D012097:Repressor Proteins / Q000737:chemistry / Q000378:metabolism*
chemical_list: D002868:Chromosomal Proteins, Non-Histone; D029968:Escherichia coli Proteins; C067035:MukB protein, E coli; D012097:Repressor Proteins; C087115:mukE protein, E coli; C087116:mukF protein, E coli; D000255:Adenosine Triphosphate