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Crystal structure of a clip-domain serine protease and functional roles of the clip domains
Piao, Shunfu,Song, Young-Lan,Kim, Jung Hyun,Park, Sam Yong,Park, Ji Won,Lee, Bok Leul,Oh, Byung-Ha,Ha, Nam-Chul Wiley (John WileySons) 2005 The EMBO journal Vol.24 No.24
<P>Clip-domain serine proteases (SPs) are the essential components of extracellular signaling cascades in various biological processes, especially in embryonic development and the innate immune responses of invertebrates. They consist of a chymotrypsin-like SP domain and one or two clip domains at the N-terminus. Prophenoloxidase-activating factor (PPAF)-II, which belongs to the noncatalytic clip-domain SP family, is indispensable for the generation of the active phenoloxidase leading to melanization, a major defense mechanism of insects. Here, the crystal structure of PPAF-II reveals that the clip domain adopts a novel fold containing a central cleft, which is distinct from the structures of defensins with a similar arrangement of cysteine residues. Ensuing studies demonstrated that PPAF-II forms a homo-oligomer upon cleavage by the upstream protease and that the clip domain of PPAF-II functions as a module for binding phenoloxidase through the central cleft, while the clip domain of a catalytically active easter-type SP plays an essential role in the rapid activation of its protease domain.</P>
Crystal structure of a clip-domain serine protease and functional roles of the clip domains
Shunfu Piao,Ha, Nam-Chul 이화여자대학교 세포신호전달연구센터 2006 고사리 세포신호전달 심포지움 Vol. No.8
Clip-domain serine proteases are the essential components of extracellular signaling cascades in various biological processes, especially in embryonic development and the innate immune responses of invertebrates. They consist of a chymotrypsin-like serine protease domain and one or two clip domains at the N-terminus. Prophenoloxidase activating factor(PPAF)-Ⅱ, which belongs to thenon-catalytic clip-domain serine protease family, is indispensable for the generation of the active phenoloxidase leading to melanization, a major defense mechanism of insects. Here, the crystal structure of PPAF-Ⅱ reveals that the clip domain adopts a novel fold containing a central cleft, which is distinct from the structures of defensins with a similar arrangement of cysteine residues. Ensuing studies demonstrated that PPAF-Ⅱ forms a homo-oligomer upon cleavage by the upstream protease and that the clip domain of PPAF-Ⅱ functions as a module for binding phenoloxidase through the central cleft, while the clip domain of a catalytically active easter-type serine protease plays an essential role in the rapid activation of its protease domain.
Periplasmic Domain of CusA in an Escherichia coli Cu+/Ag+ Transporter Has Metal Binding Sites
윤보영,Yongbin Xu,Shunfu Piao,Nahee Kim,윤정현,조현수,이강석,하남출 한국미생물학회 2010 The journal of microbiology Vol.48 No.6
The resistance nodulation division (RND)-type efflux systems are utilized in Gram-negative bacteria to export a variety of substrates. The CusCFBA system is the Cu+ and Ag+ efflux system in Escherichia coli,conferring resistance to lethal concentrations of Cu+ and Ag+. The periplasmic component, CusB, which is essential for the assembly of the protein complex, has Cu+ or Ag+ binding sites. The twelve-span membrane protein CusA is a homotrimeric transporter, and has a relatively large periplasmic domain. Here, we constructed the periplasmic domain of CusA by joining two DNA segments and then successfully expressed and purified the protein. Isothermal titration calorimetry experiments revealed Ag+ binding sites with Kds of 10-6-10-5 M. Our findings suggest that the metal binding in the periplasmic domain of CusA might play an important role in the function of the efflux pump.
Kim, Hong-Man,Xu, Yongbin,Lee, Minho,Piao, Shunfu,Sim, Se-Hoon,Ha, Nam-Chul,Lee, Kangseok American Society for Microbiology 2010 Journal of Bacteriology Vol.192 No.17
<B>ABSTRACT</B><P>Tripartite efflux pumps found in Gram-negative bacteria are involved in antibiotic resistance and toxic-protein secretion. In this study, we show, using site-directed mutational analyses, that the conserved residues located in the tip region of the α-hairpin of the membrane fusion protein (MFP) AcrA play an essential role in the action of the tripartite efflux pump AcrAB-TolC. In addition, we provide <I>in vivo</I> functional data showing that both the length and the amino acid sequence of the α-hairpin of AcrA can be flexible for the formation of a functional AcrAB-TolC pump. Genetic-complementation experiments further indicated functional interrelationships between the AcrA hairpin tip region and the TolC aperture tip region. Our findings may offer a molecular basis for understanding the multidrug resistance of pathogenic bacteria.</P>
A Synthetic Peptidoglycan Fragment as a Competitive Inhibitor of the Melanization Cascade
Park, Ji Won,Je, Byung-Rok,Piao, Shunfu,Inamura, Seiichi,Fujimoto, Yukari,Fukase, Koichi,Kusumoto, Shoichi,Sö,derhä,ll, Kenneth,Ha, Nam-Chul,Lee, Bok Luel American Society for Biochemistry and Molecular Bi 2006 The Journal of biological chemistry Vol.281 No.12