N-Terminal Truncation Does Not Affect the Location of a Conserved Tryptophan in the BLUF Domain of AppA from Rhodobacter sphaeroides

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• 作者：Masashi Unno ; Yuuki Tsukiji ; Kensuke Kubota ; Shinji Masuda
• 刊名：The Journal of Physical Chemistry B
• 出版年：2012
• 出版时间：August 2, 2012
• 年：2012
• 卷：116
• 期：30
• 页码：8974-8980
• 全文大小：324K
• 年卷期：v.116,no.30(August 2, 2012)
• ISSN：1520-5207

文摘

The flavin-binding BLUF domains are a class of blue-light receptors, and AppA is a representative of this family. Although the crystal and solution structures of several BLUF domains have already been obtained, there is a key uncertainty regarding the position of a functionally important tryptophan (Trp104 in AppA). In the first crystal structure of an N-terminally truncated BLUF domain of AppA133 (residues 17鈥?33), Trp104 was found in close proximity to flavin (Trp_in), whereas in a subsequent structure with an intact N-terminus AppA126 (residues 1鈥?26), Trp104 was exposed to the solvent (Trp_out). A recent study compared spectroscopic properties of AppA126 and AppA133 and claimed that the Trp_in conformation is an artifact of N-terminal truncation in AppA133. In this study, we compared the flavin vibrational spectra of AppA126 and AppA133 by using near-infrared excited Raman spectroscopy. In addition, the conformations as well as the environments of Trp104 were directly monitored by ultraviolet resonance Raman spectroscopy. These studies demonstrate that the N-terminal truncation does not induce the conformational switch between Trp_in and Trp_out.