Bacterial IscU is a well folded and functional single domain protein.
Iron-sulfur clusters are widely represented in most organisms, but the mechanism of their formation is not fully understood. Of the two main proteins involved in cluster formation, NifS/IscS and NifU/IscU, only the former has been well studied from a structural point of view. Here we report an extensive structural characterization of Escherichia coli IscU. We show by a variety of physico-chemical techniques that E. coli IscU construct can be expressed to high purity as a monomeric protein, characterized by an alphabeta fold with high alpha-helix content. The high melting temperature and the reversibility of the thermal unfolding curve (as measured by CD spectroscopy) hint at a well ordered stable fold. The excellent dispersion of cross peaks in the (1)H-(15)N correlation spectrum is consistent with these observations. Monomeric E. coli IscU is able to provide a scaffold for Iron-sulfur cluster assembly, but has no direct interaction with either Fe(II) or Fe(III) ions, suggesting the need of further partners to achieve a stable interaction.
Adinolfi
Salvatore
S
National Institute of Medical Research, The Ridgeway, London NW7 1AA, UK.
Rizzo
Francesca
F
Masino
Laura
L
Nair
Margie
M
Martin
Stephen R
SR
Pastore
Annalisa
A
Temussi
Piero A
PA
D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D007501:Iron / Q000737:chemistry / Q000378:metabolism; D007506:Iron-Sulfur Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D019906:Nuclear Magnetic Resonance, Biomolecular; D011485:Protein Binding; D011489:Protein Denaturation; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry; D013455:Sulfur / Q000737:chemistry; D013696:Temperature
D029968:Escherichia coli Proteins; D007506:Iron-Sulfur Proteins; C411665:IscU protein, E coli; D011994:Recombinant Proteins; D013455:Sulfur; D007501:Iron