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You searched for subject:(hexameric ATPase). Showing records 1 – 2 of 2 total matches.

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Cornell University

1. Chen, Cheng. Pch2 Is A Hexameric Ring Atpase That Remodels The Meiotic Chromosome Axis Protein Hop1.

Degree: PhD, Genetics, 2014, Cornell University

In most organisms, the accurate segregation of chromosomes during the first meiotic division requires at least one crossover between each pair of homologous chromosomes. Crossovers form in meiosis from programmed double-strand breaks (DSBs) that are preferentially repaired using the homologous chromosome as a template. The PCH2 gene of budding yeast is required to establish proper meiotic chromosome structure, and to regulate meiotic DSB repair outcomes. PCH2 was also found to promote meiotic checkpoint functions, and to maintain ribosomal DNA stability during meiosis. The major focus of my thesis research has been to elucidate the molecular mechanism of Pch2 function. Pch2 contains an AAA (ATPases Associated with diverse cellular Activities) domain and is conserved in worms, fruit flies, and mammals. I performed the first detailed biochemical analysis of Pch2, and found that purified Pch2 oligomerizes into single hexameric rings in the presence of nucleotide. In addition, I showed that Pch2 directly binds to Hop1, a critical component of the synaptonemal complex that facilitates DSB repair to form crossovers. Interestingly, Hop1 binding by Pch2 induces large conformational changes in Pch2 hexamers, suggesting that Pch2 hexamers exert mechanical forces on Hop1. Importantly, I demonstrate that Pch2 subunits coordinate their ATP hydrolysis activities to displace Hop1 from large DNA substrates, providing an explanation for the altered localization of Hop1 in pch2[DELTA] mutants that was previously observed. Based on these results and other genetic and cell biological evidences I propose that Pch2 impacts multiple meiotic chromosome functions by directly regulating Hop1 localization. The second part of my thesis involves analyzing the pro-crossover Msh4-Msh5 complex, which facilitates interhomolog crossover formation by stabilizing recombination intermediates. To analyze Msh4-Msh5 function, I assayed spore viability and crossover levels for 57 msh4 and msh5 mutants and identified threshold mutants that showed wild-type spore viability but significantly decreased crossover levels. These findings suggest that a buffering mechanism exists to ensure the obligate crossover when overall crossover levels are reduced. Advisors/Committee Members: Alani, Eric (chair), Peters, Joseph E. (committee member), Goldberg, Michael Lewis (committee member).

Subjects/Keywords: meiosis; AAA proteins; hexameric ATPase

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Chen, C. (2014). Pch2 Is A Hexameric Ring Atpase That Remodels The Meiotic Chromosome Axis Protein Hop1. (Doctoral Dissertation). Cornell University. Retrieved from http://hdl.handle.net/1813/37032

Chicago Manual of Style (16th Edition):

Chen, Cheng. “Pch2 Is A Hexameric Ring Atpase That Remodels The Meiotic Chromosome Axis Protein Hop1.” 2014. Doctoral Dissertation, Cornell University. Accessed December 05, 2020. http://hdl.handle.net/1813/37032.

MLA Handbook (7th Edition):

Chen, Cheng. “Pch2 Is A Hexameric Ring Atpase That Remodels The Meiotic Chromosome Axis Protein Hop1.” 2014. Web. 05 Dec 2020.

Vancouver:

Chen C. Pch2 Is A Hexameric Ring Atpase That Remodels The Meiotic Chromosome Axis Protein Hop1. [Internet] [Doctoral dissertation]. Cornell University; 2014. [cited 2020 Dec 05]. Available from: http://hdl.handle.net/1813/37032.

Council of Science Editors:

Chen C. Pch2 Is A Hexameric Ring Atpase That Remodels The Meiotic Chromosome Axis Protein Hop1. [Doctoral Dissertation]. Cornell University; 2014. Available from: http://hdl.handle.net/1813/37032


University of California – Berkeley

2. Thomsen, Nathan David. Structural Studies of Translocation Mechanism and Chemomechanical Coupling in Hexameric Helicases.

Degree: Molecular & Cell Biology, 2010, University of California – Berkeley

Ring-shaped oligomeric ATPases are essential for a variety of cellular processes ranging from protein and nucleic acid metabolism to organelle transport. A subset of these motor proteins, the hexameric helicases, couple the binding and hydrolysis of ATP to the physical manipulation of nucleic acids in processes such as gene regulation, DNA replication, and DNA repair. Although all known hexameric helicases belong to the P-loop ATPase protein superfamily, they have diverged into two sub-families distinguished by their opposing translocation directions along single stranded nucleic acids: the 3'-5' AAA+ and the 5'-3' RecA-like enzymes. To understand the translocation mechanism of a 5'-3' RecA-like hexameric helicase, I crystallized the Rho transcription termination factor from E. coli bound to both RNA and ADP*BeF3. After overcoming a unique case of non-merohedral twinning, I solved multiple structures of an asymmetric Rho hexamer representing potential translocation intermediates. The ligand binding states observed in the structures reveal the mechanism by which nucleic acid binding stimulates ATPase activity and how this activity is linked to nucleic acid translocation in Rho. Comparisons with the 3'-5' AAA+ hexameric helicase E1, from papillomavirus, further reveal the structural basis for translocation polarity in AAA+ and RecA-like hexameric helicases. The work presented in this dissertation helps to explain years of biochemical studies, unifies many elements of RecA-like hexameric helicase mechanism, and has implications for understanding the hexameric motor protein family as a whole.

Subjects/Keywords: Biochemistry; Molecular biology; AAA+; ATPase; Hexameric helicase; Motor; RecA; Rho

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APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Thomsen, N. D. (2010). Structural Studies of Translocation Mechanism and Chemomechanical Coupling in Hexameric Helicases. (Thesis). University of California – Berkeley. Retrieved from http://www.escholarship.org/uc/item/6r47g2db

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Thomsen, Nathan David. “Structural Studies of Translocation Mechanism and Chemomechanical Coupling in Hexameric Helicases.” 2010. Thesis, University of California – Berkeley. Accessed December 05, 2020. http://www.escholarship.org/uc/item/6r47g2db.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Thomsen, Nathan David. “Structural Studies of Translocation Mechanism and Chemomechanical Coupling in Hexameric Helicases.” 2010. Web. 05 Dec 2020.

Vancouver:

Thomsen ND. Structural Studies of Translocation Mechanism and Chemomechanical Coupling in Hexameric Helicases. [Internet] [Thesis]. University of California – Berkeley; 2010. [cited 2020 Dec 05]. Available from: http://www.escholarship.org/uc/item/6r47g2db.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Thomsen ND. Structural Studies of Translocation Mechanism and Chemomechanical Coupling in Hexameric Helicases. [Thesis]. University of California – Berkeley; 2010. Available from: http://www.escholarship.org/uc/item/6r47g2db

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

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