Document Detail


The Escherichia coli primosomal DnaT protein exists in solution as a monomer-trimer equilibrium system.
MedLine Citation:
PMID:  23418648     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The oligomerization reaction of the Escherichia coli DnaT protein has been quantitatively examined using fluorescence anisotropy and analytical ultracentrifugation methods. In solution, DnaT exists as a monomer-trimer equilibrium system. At the estimated concentration in the E. coli cell, DnaT forms a mixture of the monomer and trimer states with a 3:1 molar ratio. In spite of the modest affinity, the trimerization is a highly cooperative process, without the detectable presence of the intervening dimer. The DnaT monomer consists of a large N-terminal core domain and a small C-terminal region. The removal of the C-terminal region dramatically affects the oligomerization process. The isolated N-terminal domain forms a dimer instead of the trimer. These results indicate that the DnaT monomer possesses two structurally different, interacting sites. One site is located on the N-terminal domain, and two monomers, in the trimer, are associated through their binding sites located on that domain. The C-terminal region forms the other interacting site. The third monomer is engaged through the C-terminal regions. Surprisingly, the high affinity of the N-terminal domain dimer indicates that the DnaT monomer undergoes a conformational transition upon oligomerization, involving the C-terminal region. These data and the high specificity of the trimerization reaction, i.e., lack of any oligomers higher than a trimer, indicate that each monomer in the trimer is in contact with the two remaining monomers. A model of the global structure of the DnaT trimer based on the thermodynamic and hydrodynamic data is discussed.
Authors:
Michal R Szymanski; Maria J Jezewska; Wlodzimierz Bujalowski
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't     Date:  2013-03-08
Journal Detail:
Title:  Biochemistry     Volume:  52     ISSN:  1520-4995     ISO Abbreviation:  Biochemistry     Publication Date:  2013 Mar 
Date Detail:
Created Date:  2013-03-19     Completed Date:  2013-05-09     Revised Date:  2014-03-26    
Medline Journal Info:
Nlm Unique ID:  0370623     Medline TA:  Biochemistry     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1845-57     Citation Subset:  IM    
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MeSH Terms
Descriptor/Qualifier:
Amino Acid Sequence
DNA-Binding Proteins / chemistry*
Escherichia coli / chemistry*
Escherichia coli Proteins / chemistry*
Models, Molecular
Molecular Sequence Data
Protein Conformation
Protein Multimerization
Protein Structure, Tertiary
Ultracentrifugation
Grant Support
ID/Acronym/Agency:
GM46679/GM/NIGMS NIH HHS; R01 GM046679/GM/NIGMS NIH HHS
Chemical
Reg. No./Substance:
0/DNA-Binding Proteins; 0/DnaT protein, E coli; 0/Escherichia coli Proteins
Comments/Corrections

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