Residues of 14-3-3 Required for Activation of Exoenzyme S of Pseudomonas aeruginosa
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- 作者：Lixin Zhang ; Haining Wang ; Shane C. Masters ; Bingcheng Wang ; Joseph T. Barbieri ; and Haian Fu
- 刊名：Biochemistry
- 出版年：1999
- 出版时间：September 14, 1999
- 年：1999
- 卷：38
- 期：37
- 页码：12159 - 12164
- 全文大小：139K
- 年卷期：v.38,no.37(September 14, 1999)
- ISSN：1520-4995
文摘
Exoenzyme S (ExoS) is a mono-ADP-ribosyltransferase secreted by the opportunistic pathogenPseudomonas aeruginosa. ExoS requires a eukaryotic factor, the 14-3-3 protein, for enzymatic activity.Here, two aspects of the activation of the ADP-ribosyltransferase activity of ExoS by 14-3-3 proteins areexamined. Initial studies showed that several isoforms of 14-3-3, including 
chars/beta2.gif" BORDER=0 ALIGN="middle">, chars/zeta.gif" BORDER=0 >, chars/eta.gif" BORDER=0 >, chars/sigma.gif" BORDER=0 >, and chars/tau.gif" BORDER=0 >, activatedExoS with similar efficiency. This implicates a conserved structure in 14-3-3 that contributes to theinteraction between 14-3-3 and ExoS. One candidate structure is the conserved amphipathic groove thatmediates the 14-3-3/Raf-1 interaction. The next series of experiments examined the role of individualamino acids of the amphipathic groove of 14-3-3chars/zeta.gif" BORDER=0 > in ExoS activation and showed that ExoS activationrequired the basic residues lining the amphipathic groove of 14-3-3chars/zeta.gif" BORDER=0 > without extensive involvement ofthe hydrophobic residues. Strikingly, mutations of Val-176 of 14-3-3chars/zeta.gif" BORDER=0 > that disrupted its interaction withRaf-1 did not affect the binding and activation of ExoS by 14-3-3. Thus, ExoS selectively employs residuesin the Raf-binding groove for its association with 14-3-3 proteins.
chars/beta2.gif" BORDER=0 ALIGN="middle">, chars/zeta.gif" BORDER=0 >, chars/eta.gif" BORDER=0 >, chars/sigma.gif" BORDER=0 >, and chars/tau.gif" BORDER=0 >, activatedExoS with similar efficiency. This implicates a conserved structure in 14-3-3 that contributes to theinteraction between 14-3-3 and ExoS. One candidate structure is the conserved amphipathic groove thatmediates the 14-3-3/Raf-1 interaction. The next series of experiments examined the role of individualamino acids of the amphipathic groove of 14-3-3chars/zeta.gif" BORDER=0 > in ExoS activation and showed that ExoS activationrequired the basic residues lining the amphipathic groove of 14-3-3chars/zeta.gif" BORDER=0 > without extensive involvement ofthe hydrophobic residues. Strikingly, mutations of Val-176 of 14-3-3chars/zeta.gif" BORDER=0 > that disrupted its interaction withRaf-1 did not affect the binding and activation of ExoS by 14-3-3. Thus, ExoS selectively employs residuesin the Raf-binding groove for its association with 14-3-3 proteins.