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The role of cross‐interface salt bridges in SCAN domain dimerization specificity
Author(s) -
Kasanov Jeremy,
Ivanov Dimitri,
Wagner Gerhard,
Collins Tucker
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.5.a271
Subject(s) - dimer , chemistry , salt bridge , hydrogen bond , crystallography , nuclear magnetic resonance spectroscopy , circular dichroism , protein secondary structure , amino acid , stereochemistry , domain (mathematical analysis) , biophysics , molecule , biochemistry , mutant , biology , gene , mathematical analysis , mathematics , organic chemistry
The SCAN domain is a dimerization domain located at the amino terminus of about 10% of the estimated 700 human C 2 H 2 zinc finger proteins. These domains interact selectively, forming homo‐ and heterodimers. However, what determines SCAN‐SCAN dimerization specificity is unknown. Using NMR spectroscopy, we have recently solved the structure of the isolated SCAN homodimer and demonstrated that it is a domain‐swapped dimer (Ivanov et. al, Mol. Cell 17 –143, 2005). Two arginine residues, R68 and R72, on one SCAN domain were found to lie across the domain interface from glutamic acid residues E83 and E87 (Figure 1). To determine if a salt bridge or hydrogen bond is formed, point mutations were introduced separately into the SCAN domain at these four positions. NMR and circular dichroism (CD) spectroscopy showed that these mutations did not alter the secondary structure of the domain. Interestingly, temperature scanning CD spectroscopy showed that R68E, R72E and E83R mutations reduced the stability of the dimer, while the E87R mutation had no effect on dimer stability. While E83 is highly conserved in SCAN family members, positions 68 and 72 are quite variable. Several SCAN domains, however, do contain conserved arginines at these positions. This data suggests that the ionic interactions between R68, R72 and E83 may be important recognition elements that govern dimerization for this large family of transcription factors. 1