tailieunhanh - Báo cáo khoa học: Bacterial IscU is a well folded and functional single domain protein

Iron–sulfur clusters are widely represented in most organ-isms, 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 anextensive structural characterizationofEscherichia coliIscU. We show by a variety of physico-chemical tech-niques thatE. coliIscU construct can be expressed to high purity as a monomeric protein, characterized by anabfold withhigha-helix content. . | Eur. J. Biochem. 271 2093-2100 2004 FEBS 2004 doi Bacterial IscU is a well folded and functional single domain protein Salvatore Adinolfi1 Francesca Rizzo1 Laura Masino1 Maraie Nair1. Stenhen R. Martin1 Annalisa Pastore1 and Piero A. Temussi1 2 1 National Institute of Medical Research London UK 2University of Naples Federico II Napoli Italy 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 ab fold with high a-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 1H-15N 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. Keywords Friedreich ataxia iron-sulfur cluster NMR thermal stability. Metalloproteins hosting iron-sulfur clusters isc are present in most organisms 1 2 and are involved in several processes including electron transport generation of organic radicals and regulatory processes. Although Ironsulfur clusters are widely diffuse in nature the detailed steps leading to their assembly are still mostly unknown. Owing to the toxicity of iron and sulfide ions it is probable that the formation of Fe-S clusters is mediated by protein-protein interactions. NifS and NifU the specific proteins .