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![[Figure 1]](qh5070fig1mag.jpg)
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Figure 1
STF-HD oligomerizes upon binding DNA. (a) Chromatographs of the apoprotein (blue) and the DNA complex (orange) from a Superdex S200 column. The estimated molecular weight (MW) of the apo protein from the retention volume is about 20 kDa, which is larger than the theoretical MW of 12.5 kDa of STF-HD due to its elongated shape. These data are in agreement with the STF-HD monomer, which has a calculated apparent MW of 22.5 kDa in solution based on its calculated hydrodynamic radius of 23.4 Å (Fleming & Fleming, 2018  ) using the current crystal structure. The A280/A260 of the peak faction collected from the complex had a value of 1.61, suggesting a 1:4 DNA:protein ratio in the complex. (b) EMSA analysis of STF-HD binding to the promoter DNA. 5′ 6-FAM-labeled 22 bp DNA (top, MtLOB39 promoter; bottom, MtAS2 promoter) was used in the assay. Left (black and white): the fluorescence signal from the DNA is captured. Right: the same gel stained with Coomassie Blue to show the protein. Lane 1, 5′ 6-FAM-labeled DNA; lane 2, apoprotein; lanes 3–6, DNA and protein mixed at molar ratios of 1:1, 1:2, 1:4 and 1:8, respectively. Note that STF-HD forms a stable complex with DNA when mixed in a 1:4 molar ratio (DNA:protein) in lane 5. |
![[Figure 1]](qh5070fig1.jpg)
 | STRUCTURAL BIOLOGY |
ISSN: 2059-7983
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