THE MAJOR COLD SHOCK PROTEIN OF BACILLUS-SUBTILIS CSPB BINDS WITH HIGH-AFFINITY TO THE ATTGG- AND CCAAT SEQUENCES IN SINGLE-STRANDED OLIGONUCLEOTIDES

We have characterized the nucleic acid binding properties of the major cold shock protein of Bacillus subtilis, CspB. CspB is a member of th e cold shock domain (CSD) family, which is widespread among pro- and e ukaryotes and shares the nucleic acid binding domain CSD. The CSD doma in is highly conserved and binds with strong affinity to the Y-box mot if, a cis-element that contains the CTGATTGG(C)/(C)(T)/(T)AA sequence. In a series of gel retardation experiments using oligonucleotides, wh ich contain the Y-box motif and altered sequences, we show the prefere ntial binding of CspB to single-stranded DNA that contains the ATTGG a s well as the complementary CCAAT Y-box core sequence. In contrast Csp B exhibits lower affinity to altered Y-box core sequences. Dependent o n the length of the oligonucleotide and the degree of sequence deviati on from the Y-box core sequence 3- to over 10-fold overexcess of CspB was needed for complete retardation.