Characterization of an unusual cold shock protein from Staphylococcus aureus.
Of the three cold shock proteins expressed by Staphylococcus aureus, CspC is induced poorly by cold but strongly by various antibiotics and toxic chemicals. Using a purified CspC, here we demonstrate that it exists as a monomer in solution, possesses primarily β-sheets, and bears substantial structural similarity with other bacterial Csps. Aggregation of CspC was initiated rapidly at temperatures above 40 °C, whereas, the Gibbs free energy of stabilization of CspC at 0 M GdmCl was estimated to be +1.6 kcal mol(-1), indicating a less stable protein. Surprisingly, CspC showed stable binding with ssDNA carrying a stretch of more than three thymine bases and binding with such ssDNA had not only stabilized CspC against proteolytic degradation but also quenched the fluorescence intensity from its exposed Trp residue. Analysis of quenching data indicates that each CspC molecule binds with ∼5 contiguous thymine bases of the above ssDNA and binding is cooperative in nature.
Chanda
Palas K
PK
Department of Biochemistry, Bose Institute, Kolkata, India.
Bandhu
Amitava
A
Jana
Biswanath
B
Mondal
Rajkrishna
R
Ganguly
Tridib
T
Sau
Keya
K
Lee
Chia Y
CY
Chakrabarti
Gopal
G
Sau
Subrata
S
D000900:Anti-Bacterial Agents / Q000633:toxicity; D001426:Bacterial Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D002942:Circular Dichroism; D003080:Cold Temperature; D004277:DNA, Single-Stranded / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D006360:Heat-Shock Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D008958:Models, Molecular; D011485:Protein Binding; D011487:Protein Conformation; D011489:Protein Denaturation; D055550:Protein Stability; D013211:Staphylococcus aureus / Q000378:metabolism* / Q000528:radiation effects*; D013941:Thymine / Q000378:metabolism
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; C088099:CspC protein, bacteria; D004277:DNA, Single-Stranded; D006360:Heat-Shock Proteins; D013941:Thymine
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