Ml proteins from Mesorhizobium loti and MucR from Brucella abortus: an AT-rich core DNA-target site and oligomerization ability
Date
2017-11-17
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Authors
Baglivo, Ilaria
Pirone, Luciano
Pedone, Emilia Maria
Pitzer, Joshua Edison
Muscariello, Lidia
Marino, Maria Michela
Malgieri, Gaetano
Freschi, Andrea
Chambery, Angela
Roop, Roy-Martin II
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Abstract
Mesorhizobium loti contains ten genes coding for proteins sharing high amino acid sequence identity with members of the Ros/MucR transcription factor family. Five of these Ros/MucR family members from Mesorhizobium loti (Ml proteins) have been recently structurally and functionally characterized demonstrating that Ml proteins are DNA-binding proteins. However, the DNA-binding studies were performed using the Ros DNA-binding site with the Ml proteins. Currently, there is no evidence as to when the Ml proteins are expressed during the Mesorhizobium loti life cycle as well as no information concerning their natural DNA-binding site. In this study, we examine the ml genes expression profile in Mesorhizobium loti and show that ml1, ml2, ml3 and ml5 are expressed during planktonic growth and
in biofilms. DNA-binding experiments show that the Ml proteins studied bind a conserved AT-rich site
in the promoter region of the exoY gene from Mesorhizobium loti and that the proteins make important contacts with the minor groove of DNA. Moreover, we demonstrate that the Ml proteins studied form higher-order oligomers through their N-terminal region and that the same AT-rich site is recognized by MucR from Brucella abortus using a similar mechanism involving contacts with the minor groove of DNA and oligomerization.
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DOI
10.1038/s41598-017-16127-5