title: Tuned SMC Arms Drive Chromosomal Loading of Prokaryotic Condensin.
abstract: SMC proteins support vital cellular processes in all domains of life by organizing chromosomal DNA. They are composed of ATPase "head" and "hinge" dimerization domains and a connecting coiled-coil "arm." Binding to a kleisin subunit creates a closed tripartite ring, whose ∼47-nm-long SMC arms act as barrier for DNA entrapment. Here, we uncover another, more active function of the bacterial Smc arm. Using high-throughput genetic engineering, we resized the arm in the range of 6-60 nm and found that it was functional only in specific length regimes following a periodic pattern. Natural SMC sequences reflect these length constraints. Mutants with improper arm length or peptide insertions in the arm efficiently target chromosomal loading sites and hydrolyze ATP but fail to use ATP hydrolysis for relocation onto flanking DNA. We propose that SMC arms implement force transmission upon nucleotide hydrolysis to mediate DNA capture or loop extrusion.
authors.affiliation: Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Bürmann
authors.affiliation: Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany.
authors.forename: Alrun
authors.initials: A
authors.lastname: Basfeld
authors.affiliation: Department of Fundamental Microbiology, University of Lausanne, Bâtiment Biophore, 1015 Lausanne, Switzerland.
authors.forename: Roberto
authors.initials: R
authors.lastname: Vazquez Nunez
authors.affiliation: Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany.
authors.forename: Marie-Laure
authors.initials: ML
authors.lastname: Diebold-Durand
authors.affiliation: Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany.
authors.forename: Larissa
authors.initials: L
authors.lastname: Wilhelm
authors.affiliation: Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany; Department of Fundamental Microbiology, University of Lausanne, Bâtiment Biophore, 1015 Lausanne, Switzerland. Electronic address: stephan.gruber@unil.ch.
authors.forename: Stephan
authors.initials: S
authors.lastname: Gruber
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000378:metabolism; D001412:Bacillus subtilis / Q000201:enzymology* / Q000235:genetics; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001665:Binding Sites; D018797:Cell Cycle Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002876:Chromosomes, Bacterial / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005818:Genetic Engineering / Q000379:methods; D057166:High-Throughput Screening Assays; D006868:Hydrolysis; D046912:Multiprotein Complexes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D009690:Nucleic Acid Conformation; D011485:Protein Binding; D000072756:Protein Conformation, alpha-Helical; D013329:Structure-Activity Relationship
chemical_list: D001426:Bacterial Proteins; D018797:Cell Cycle Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D046912:Multiprotein Complexes; C118650:SMC protein, Bacteria; C108312:condensin complexes; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases
keywords: ParB; SMC; Smc/ScpAB; chromosome segregation; cohesin; coiled coil; condensin; heptad repeat; kleisin; periodicity