Structural studies on Vibrio cholerae ToxR periplasmic and cytoplasmic domains.
The transcription activator ToxR controls the expression of cholera toxin, pilus colonization factor and outer membrane protein in Vibrio cholerae. It binds to the 5'-TTTTGAT-3' tandemly repeated DNA sequence in the cholera toxin promoter region. ToxR is a membrane protein having distinct periplasmic and cytoplasmic domains. The two domains have been cloned, over-expressed and purified for structural studies. The cytoplasmic domain is more compact than the periplasmic domain. The periplasmic domain exists as dimer due to the presence of an interchain disulfide linkage, while the cytoplasmic domain is monomeric in solution implying the importance of the disulfide bond to homodimerize the native ToxR. By replacing one of the cysteines C293 with alanine, using site-directed mutagenesis, a C293A mutant was created at the periplasmic domain to elucidate the role of cysteine in dimerization of ToxR.
Chatterjee
Tanaya
T
Department of Biochemistry, Bose Institute, P-1/12 CIT Scheme VIIM, Calcutta 700054, India.
Saha
Rudra Prasad
RP
Chakrabarti
Pinak
P
D000409:Alanine / Q000235:genetics; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution / Q000235:genetics; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics; D003545:Cysteine / Q000235:genetics; D003593:Cytoplasm / Q000737:chemistry* / Q000235:genetics; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics; D019281:Dimerization; D004220:Disulfides / Q000737:chemistry / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D033903:Periplasmic Proteins / Q000737:chemistry* / Q000235:genetics; D017434:Protein Structure, Tertiary / Q000235:genetics; D014157:Transcription Factors / Q000737:chemistry* / Q000235:genetics; D014734:Vibrio cholerae / Q000737:chemistry* / Q000235:genetics / Q000472:pathogenicity
D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D004220:Disulfides; D033903:Periplasmic Proteins; D014157:Transcription Factors; C499324:toxR protein, Vibrio cholerae; D003545:Cysteine; D000409:Alanine