The Hemophore HasA from Yersinia pestis (HasAyp) Coordinates Hemin with a Single Residue, Tyr75, and with Minimal Conformational Change

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• 作者：Ritesh Kumar ; Scott Lovell ; Hirotoshi Matsumura ; Kevin P. Battaile ; Pierre Mo毛nne-Loccoz ; Mario Rivera
• 刊名：Biochemistry
• 出版年：2013
• 出版时间：April 23, 2013
• 年：2013
• 卷：52
• 期：16
• 页码：2705-2707
• 全文大小：206K
• 年卷期：v.52,no.16(April 23, 2013)
• ISSN：1520-4995

文摘

Hemophores from Serratia marcescens (HasA_sm) and Pseudomonas aeruginosa (HasA_p) bind hemin between two loops, which harbor the axial ligands H32 and Y75. Hemin binding to the Y75 loop triggers closing of the H32 loop and enables binding of H32. Because Yersinia pestis HasA (HasA_yp) presents a Gln at position 32, we determined the structures of apo- and holo-HasA_yp. Surprisingly, the Q32 loop in apo-HasA_yp is already in the closed conformation, but no residue from the Q32 loop binds hemin in holo-HasA_yp. In agreement with the minimal reorganization between the apo- and holo-structures, the hemin on-rate is too fast to detect by conventional stopped-flow measurements.