title: Assembly of the hexameric Escherichia coli arginine repressor investigated by nano-electrospray ionization time-of-flight mass spectrometry.
abstract: The arginine repressor (ArgR) from Escherichia coli regulates genes for L-arginine metabolism and is a required recombination factor for colE1 plasmid replication. Both functions require binding of L-arginine to the protein. In this work, nano-electrospray ionization time-of-flight mass spectrometry (nano-ESI-TOFMS) is used to study conformational and oligomeric states of intact ArgR and its isolated structural domains. In agreement with X-ray diffraction studies, it is shown that ArgR oligomerizes to form hexamers in both the presence and absence of L-arginine, and the basic unit of oligomerization appears to be the trimer. Higher-order assembly into dodecamers is also detected. The isolated C-terminal domain is found to associate into trimers and hexamers whereas the N-terminal domain is detected in its monomeric form. The observed species distributions suggest a role for the N-terminal domain in hexamer stabilization.
authors.affiliation: Institute of Organic Chemistry, Johannes Kepler University, Altenbergerstrasse 69, 4040 Linz, Austria.
authors.forename: Mária
authors.initials: M
authors.lastname: Samalíková
authors.forename: Jannette
authors.initials: J
authors.lastname: Carey
authors.forename: Rita
authors.initials: R
authors.lastname: Grandori
mesh_terms: D004926:Escherichia coli / Q000737:chemistry*; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000378:metabolism*; D015870:Gene Expression; D020836:Protein Structure, Quaternary; D012097:Repressor Proteins / Q000737:chemistry* / Q000378:metabolism*; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*
chemical_list: C490177:ArgR protein, E coli; D029968:Escherichia coli Proteins; D012097:Repressor Proteins