کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
5371393 | 1388818 | 2011 | 10 صفحه PDF | دانلود رایگان |

We have previously shown that formation of a 1:1 fully wrapped complex of Escherichia coli SSB tetramer with (dT)70 displays a temperature-dependent sign reversal of the binding heat capacity (ÎCP). Here we examine SSB binding to shorter oligodeoxynucleotides ((dX)35) to probe whether this effect requires binding of one or two (dX)35 molecules per SSB tetramer. We find that the ÎCP for the first molecule of (dX)35 is always negative. However, a sign reversal of ÎCP from negative to positive occurs with increasing temperature for binding of the second (dX)35. This striking behavior of ÎCP for the second (dX)35 appears linked to conformational changes within the ssDNA-SSB complex that are required to form a fully wrapped (SSB)65 binding mode. These results also underscore that binding heat capacities of macromolecular interactions have multiple origins that cannot be understood simply on the basis of examining static structures.
Research highlights⺠Binding of the first and the second molecule of (dT)35 to EcoSSB occurs with binding heat capacities opposite in sign ⺠A positive ÎCp observed for binding of the second (dT)35 is similar to what is observed for binding of (dT)70 ⺠This suggests a conformational rearrangement to form a fully wrapped SSB-DNA complex.
Journal: Biophysical Chemistry - Volume 159, Issue 1, November 2011, Pages 48-57