scholarly journals Bacterial chromosome segregation: structure and DNA binding of the Soj dimer ? a conserved biological switch

2005 ◽  
Vol 24 (2) ◽  
pp. 270-282 ◽  
Author(s):  
Thomas A Leonard ◽  
P Jonathan Butler ◽  
Jan L�we
Keyword(s):  
Dna Binding ◽  
Chromosome Segregation ◽  
Bacterial Chromosome ◽  
Segregation Structure

scholarly journals Identification of overlapping DNA-binding and centromere-targeting domains in the human kinetochore protein CENP-C.

1996 ◽  
Vol 16 (7) ◽  
pp. 3576-3586 ◽  
Author(s):  
C H Yang ◽  
J Tomkiel ◽  
H Saitoh ◽  
D H Johnson ◽  
W C Earnshaw
Keyword(s):  
Dna Binding ◽  
Chromosome Segregation ◽  
Mitotic Spindle ◽  
Mammalian Cells ◽  
In Vitro Assays ◽  
Centromeric Heterochromatin ◽  
Structural Protein ◽  
Chromosomal Site

The kinetochore in eukaryotes serves as the chromosomal site of attachment for microtubules of the mitotic spindle and directs the movements necessary for proper chromosome segregation. In mammalian cells, the kinetochore is a highly differentiated trilaminar structure situated at the surface of the centromeric heterochromatin. CENP-C is a basic, DNA-binding protein that localizes to the inner kinetochore plate, the region that abuts the heterochromatin. Microinjection experiments using antibodies specific for CENP-C have demonstrated that this protein is required for the assembly and/or stability of the kinetochore as well as for a timely transition through mitosis. From these observations, it has been suggested that CENP-C is a structural protein that is involved in the organization or the kinetochore. In this report, we wished to identify and map the functional domains of CENP-C. Analysis of CENP-C truncation mutants expressed in vivo demonstrated that CENP-C possesses an autonomous centromere-targeting domain situated at the central region of the CENP-C polypeptide. Similarly, in vitro assays revealed that a region of CENP-C with the ability to bind DNA is also located at the center of the CENP-C molecule, where it overlaps the centromere-targeting domain.

scholarly journals Facilitated Dissociation of a Nucleoid Protein from the Bacterial Chromosome

2016 ◽  
Vol 198 (12) ◽  
pp. 1735-1742 ◽  
Author(s):  
Nastaran Hadizadeh ◽  
Reid C. Johnson ◽  
John F. Marko
Keyword(s):  
Gene Regulation ◽  
Dna Binding ◽  
Protein Concentration ◽  
Model Systems ◽  
Bacterial Chromosome ◽  
Regulatory Function ◽  
Content Type ◽  
E Coli ◽  
Dna Double Helix

ABSTRACTOff-rates of proteins from the DNA double helix are widely considered to be dependent only on the interactions inside the initially bound protein-DNA complex and not on the concentration of nearby molecules. However, a number of recent single-DNA experiments have shown off-rates that depend on solution protein concentration, or “facilitated dissociation.” Here, we demonstrate that this effect occurs for the majorEscherichia colinucleoid protein Fis on isolated bacterial chromosomes. We isolatedE. colinucleoids and showed that dissociation of green fluorescent protein (GFP)-Fis is controlled by solution Fis concentration and exhibits an “exchange” rate constant (kexch) of ≈104M−1s−1, comparable to the rate observed in single-DNA experiments. We also show that this effect is strongly salt dependent. Our results establish that facilitated dissociation can be observedin vitroon chromosomes assembledin vivo.IMPORTANCEBacteria are important model systems for the study of gene regulation and chromosome dynamics, both of which fundamentally depend on the kinetics of binding and unbinding of proteins to DNA. In experiments on isolatedE. colichromosomes, this study showed that the prolific transcription factor and chromosome packaging protein Fis displays a strong dependence of its off-rate from the bacterial chromosome on Fis concentration, similar to that observed inin vitroexperiments. Therefore, the free cellular DNA-binding protein concentration can strongly affect lifetimes of proteins bound to the chromosome and must be taken into account in quantitative considerations of gene regulation. These results have particularly profound implications for transcription factors where DNA binding lifetimes can be a critical determinant of regulatory function.

Bacterial Chromosome Segregation

2002 ◽  
Vol 56 (1) ◽  
pp. 567-597 ◽  
Author(s):  
Geoffrey C. Draper ◽  
James W. Gober
Keyword(s):  
Chromosome Segregation ◽  
Bacterial Chromosome

scholarly journals Bacterial Chromosome Segregation: Is There a Mitotic Apparatus?

Cell ◽  
1997 ◽  
Vol 88 (5) ◽  
pp. 577-579 ◽  
Author(s):  
Robert T. Wheeler ◽  
Lucy Shapiro
Keyword(s):  
Chromosome Segregation ◽  
Bacterial Chromosome ◽  
Mitotic Apparatus

scholarly journals Retinoblastoma Protein Enhances the Fidelity of Chromosome Segregation Mediated by hsHec1p

2000 ◽  
Vol 20 (10) ◽  
pp. 3529-3537 ◽  
Author(s):  
Lei Zheng ◽  
Yumay Chen ◽  
Daniel J. Riley ◽  
Phang-Lang Chen ◽  
Wen-Hwa Lee
Keyword(s):  
Dna Binding ◽  
Chromosome Segregation ◽  
Cell Cycle Progression ◽  
Retinoblastoma Protein ◽  
Binding Activity ◽  
Yeast Cells ◽  
Temperature Sensitive ◽  
Cycle Progression ◽  
Dna Binding Activity ◽  
M Phase

ABSTRACT Retinoblastoma protein (Rb) plays important roles in cell cycle progression and cellular differentiation. It may also participate in M phase events, although heretofore only circumstantial evidence has suggested such involvement. Here we show that Rb interacts, through an IxCxE motif and specifically during G2/M phase, with hsHec1p, a protein essential for proper chromosome segregation. The interaction between Rb and hsHec1p was reconstituted in a yeast strain in which human hsHEC1 rescues the null mutation of scHEC1. Expression of Rb reduced chromosome segregation errors fivefold in yeast cells sustained by a temperature-sensitive (ts) hshec1-113 allele and enhanced the ability of wild-type hsHec1p to suppress lethality caused by a ts smc1mutation. The interaction between Hec1p and Smc1p was important for the specific DNA-binding activity of Smc1p. Expression of Rb restored part of the inactivated function of hshec1-113p and thereby increased the DNA-binding activity of Smc1p. Rb thus increased the fidelity of chromosome segregation mediated by hsHec1p in a heterologous yeast system.

scholarly journals Cell cycle coordination and regulation of bacterial chromosome segregation dynamics by polarly localized proteins

2010 ◽  
Vol 29 (18) ◽  
pp. 3068-3081 ◽  
Author(s):  
Whitman B Schofield ◽  
Hoong Chuin Lim ◽  
Christine Jacobs-Wagner
Keyword(s):  
Cell Cycle ◽  
Chromosome Segregation ◽  
Bacterial Chromosome

scholarly journals Fission Yeast Homologs of Human CENP-B Have Redundant Functions Affecting Cell Growth and Chromosome Segregation

2000 ◽  
Vol 20 (8) ◽  
pp. 2852-2864 ◽  
Author(s):  
Mary Baum ◽  
Louise Clarke
Keyword(s):  
Dna Binding ◽  
Fission Yeast ◽  
Dna Sequence ◽  
Chromosome Segregation ◽  
Binding Proteins ◽  
Dna Binding Proteins ◽  
Central Core ◽  
Cell Extracts ◽  
Redundant Functions

ABSTRACT Two functionally important DNA sequence elements in centromeres of the fission yeast Schizosaccharomyces pombe are the centromeric central core and the K-type repeat. Both of these DNA elements show internal functional redundancy that is not correlated with a conserved DNA sequence. Specific, but degenerate, sequences in these elements are bound in vitro by the S. pombeDNA-binding proteins Abp1p (also called Cbp1p) and Cbhp, which are related to the mammalian centromere DNA-binding protein CENP-B. In this study, we determined that Abp1p binds to at least one of its target sequences within S. pombe centromere II central core (cc2) DNA with an affinity (Ks = 7 × 109 M−1) higher than those of other known centromere DNA-binding proteins for their cognate targets. In vivo, epitope-tagged Cbhp associated with centromeric K repeat chromatin, as well as with noncentromeric regions. Likeabp1+/cbp1 +, we found thatcbh + is not essential in fission yeast, but a strain carrying deletions of both genes (Δabp1 Δcbh) is extremely compromised in growth rate and morphology and missegregates chromosomes at very high frequency. The synergism between the two null mutations suggests that these proteins perform redundant functions in S. pombe chromosome segregation. In vitro assays with cell extracts with these proteins depleted allowed the specific assignments of several binding sites for them within cc2 and the K-type repeat. Redundancy observed at the centromere DNA level appears to be reflected at the protein level, as no single member of the CENP-B-related protein family is essential for proper chromosome segregation in fission yeast. The relevance of these findings to mammalian centromeres is discussed.

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