Structure of the nucleoid-associated protein Cnu reveals common binding sites for H-NS in Cnu and Hha.
Cnu is a nucleoid protein that has a high degree of sequence homology with Hha/YmoA family proteins, which bind to chromatin and regulate the expression of Escherichia coli virulence genes in response to changes in temperature or ionic strength. Here, we determined its solution structure and dynamic properties and mapped H-NS binding sites. Cnu consists of three alpha helices that are comparable with those of Hha, but it has significant flexibility in the C-terminal region and lacks a short alpha helix present in Hha. Upon increasing ionic strength, the helical structure of Cnu is destabilized, especially at the ends of the helices. The dominant H-NS binding sites, located at helix 3 as in Hha, reveal a common structural platform for H-NS binding. Our results may provide structural and dynamic bases for the similarity and dissimilarity between Cnu and Hha functions.
Bae
Sung-Hun
SH
Department of Chemistry, KAIST, 373-1 Guseong-Dong Yuseong-Gu, Daejeon 305-701, Republic of Korea.
Liu
Dinan
D
Lim
Heon M
HM
Lee
Younghoon
Y
Choi
Byong-Seok
BS
D001426:Bacterial Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism*; D001665:Binding Sites; D002942:Circular Dichroism; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D011487:Protein Conformation; D017510:Protein Folding
D001426:Bacterial Proteins; C505237:Cnu protein, E coli; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; C031908:H-NS protein, bacteria; C079209:hha protein, E coli