The backbone structure of the major cold-shock protein CS7.4 of Escherichia coli in solution includes extensive beta-sheet structure.
CS7.4 is the major cold-shock protein specifically expressed to a level as high as 13% of the total cellular protein within the first hour when Escherichia coli cell culture is shifted from 37 to 15 degrees C [Goldstein et al. (1990) Proc. Natl. Acad. Sci. USA 87, 283-287]. It consists of 70 amino acid residues with a very high content of aromatic residues. CS7.4 was overproduced and purified to homogeneity. Its secondary structure was analyzed by examining circular dichroism at both the far and near-UV regions; the results suggest that the protein is largely beta-sheet in conformation. The predominance of beta-sheet structure in the protein was confirmed by using Fourier-transform infrared spectroscopy. A folded compact conformation was also verified by fluorescence emission spectroscopy. We evaluated Tm, delta H, and delta S from the thermal denaturation profile of the protein. Unusual spectral features observed in the far-UV region are attributed to the high content of aromatic residues. The protein is relatively small and contains no disulfide bonds. However, it is surprisingly stable to heat denaturation.
Chatterjee
S
S
Department of Biochemistry, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey at Rutgers, Piscataway 08854.
Jiang
W
W
Emerson
S D
SD
Inouye
M
M
D001426:Bacterial Proteins / Q000737:chemistry* / Q000302:isolation & purification; D001483:Base Sequence; D002852:Chromatography, Ion Exchange; D002942:Circular Dichroism; D003001:Cloning, Molecular; D004220:Disulfides; D004926:Escherichia coli / Q000737:chemistry*; D015870:Gene Expression / Q000235:genetics; D006358:Hot Temperature; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D013050:Spectrometry, Fluorescence; D013056:Spectrophotometry, Ultraviolet; D017550:Spectroscopy, Fourier Transform Infrared; D013816:Thermodynamics; D014157:Transcription Factors / Q000737:chemistry* / Q000302:isolation & purification
D001426:Bacterial Proteins; D004220:Disulfides; D014157:Transcription Factors; C062260:cold shock protein CS7.4, Bacteria