成孔毒素(Pore-forming toxins, PFTs)通常与细菌等原核生物的致病机理相关, 在真核生物中, 这类蛋白在免疫、胚胎发育、神经细胞迁移等方面发挥着重要作用。其中球状蛋白成孔毒素中的两大家族, 胆固醇结合细胞溶素(Cholesterol-dependent cytolysins, CDCs)和攻膜复合体/穿孔素超家族(Membrane attack complex/perforin superfamily, MACPF)以其独特的分子构型和功能受到研究者的关注。CDCs由革兰氏阳性细菌产生, 在细菌的侵染过程中发挥裂解靶细胞膜的作用; 在真核生物中, MACPF蛋白同时具有裂解和非裂解两种形式。目前, 对于以产气荚膜梭菌溶血素(PFO)为代表的CDCs蛋白的结构及分子机制了解得较为透彻, 近年来晶体学及生物化学研究揭示, 尽管CDCs和MACPF这两大家族成孔毒素在氨基酸序列水平上存在较大差异, 但它们共同的折叠模式预示: MACPF蛋白以一种类似于CDCs的成孔机制来行使其裂解靶膜的功能。文章对这两大家族成孔毒素的结构、成孔机制以及目前的研究热点问题予以综述, 为该领域今后的研究提供有益参考。
Pore-forming toxins (PFTs) are commonly associated with bacterial and other prokaryote pathogenesis. In eukaryotes, PFTs play important roles in immunity, embryonic development and neural-cell migration. Two families of globular protein PFTs: the cholesterol-dependent cytolysins (CDCs) and the membrane attack complex/perforin superfamily (MACPF), arrest researchers’ attention due to their unique molecular configuration and the function. CDCs are produced by Gram-positive bacteria and disrupt the membrane of host cells during infection. In eukaryotes, MACPF proteins have both lytic and non-lytic roles. With perfringolysin O (PFO) for example, the structure and molecular mechanism of CDCs are relatively well characterized. Recently crystallographic together with biochemical studies revealed that although MACPF and CDCs were extremely divergent at the amino acid sequence level, their common fold suggests that lytic MACPF proteins use a CDC-like mechanism of membrane disruption. This paper focuses on the structure, molecular mechanism of pore-formation and the research hotspot of the two families of PFTs, providing valuable clues for the future research in this field.
[1] Nagai H, Oshiro N, Takuwa-Kuroda K, Iwanaga S, Nozaki M, Nakajima T. Novel proteinaceous toxins from the nematocyst venom of the Okinawan sea anemone Phyl-lodiscus semoni Kwietniewski. Biochem Biophys Res Commun, 2002, 294(4): 760–763.
[2] Parker MW, Feil SC. Pore-forming protein toxins: from structure to function. Prog Biophys Mol Biol, 2005, 88(1): 91–142.
[3] Aroian R, van der Goot FG. Pore-forming toxins and cel-lular non-immune defenses (CNIDs). Curr Opin Microbiol, 2007, 10(1): 57–61.
[4] van der Goot G (Ed). Pore-forming toxins In: Current Topics in Microbiology and Immunology, 1st edition. Springer Verlag, Berlin Heidelberg, 2001.
[5] Balachandran P, Hollingshead SK, Paton JC, Briles DE. The autolytic enzyme LytA of Streptococcus pneumoniae is not responsible for releasing pneumolysin. J Bacteriol, 2001, 183(10): 3108–3116.
[6] Rosado CJ, Kondos S, Bull TE, Kuiper MJ, Law RHP, Buckle AM, Voskoboinik I, Bird PI, Trapani JA, Whisstock JC, Dunstone MA. The MACPF/CDC family of pore-forming toxins. Cell Microbiol, 2008, 10(9): 1765–1774.
[7] Gonzalez MR, Bischofberger M, Pernot L, van der Goot FG, Frêche B. Bacterial pore-forming toxins: the (w)hole story? Cell Mol Life Sci, 2008, 65(3): 493–507.
[8] Soltani CE, Hotze EM, Johnson AE, Tweten RK. Specific protein-membrane contacts are required for prepore and pore assembly by a cholesterol-dependent cytolysin. J Biol Chem, 2007, 282(21): 15709–15716.
[9] Soltani CE, Hotze EM, Johnson AE, Tweten RK. Struc-tural elements of the cholesterol-dependent cytolysins that are responsible for their cholesterol-sensitive membrane interactions. Proc Natl Acad Sci USA, 2007, 104(51): 20226–20231.
[10] Rosado CJ, Buckle AM, Law RHP, Butcher RE, Kan WT, Bird CH, Ung K, Browne KA, Baran K, Bash-tannyk-Puhalovich TA, Faux NG, Wong W, Porter CJ, Pike RN, Ellisdon AM, Pearce MC, Bottomley SP, Emsley J, Smith AI, Rossjohn J, Hartland EL, Voskoboinik I, Tra-pani JA, Bird PI, Dunstone MA, Whisstock JC. A common fold mediates vertebrate defense and bacterial attack. Science, 2007, 317(5844): 1548–1551.
[11] Lukoyanova N, Saibil HR. Friend or foe: the same fold for attack and defense. Trends Immunol, 2008, 29(2): 51–53.
[12] Slade DJ, Lovelace LL, Chruszcz M. Crystal structure of the MACPF domain of human complement protein C8α in complex with the C8γ subunit. J Mol Biol, 2008, 379(2): 331–342.
[13] Watson NFS, Durrant LG, Madjd Z, Ellis IO, Scholefield JH, Spendlove I. Expression of the membrane complement regulatory protein CD59 (protectin) is associated with re-duced survival in colorectal cancer patients. Cancer Immunol Immunother, 2006, 55(8): 973–980.
[14] Harhausen D, Khojasteh U, Stahel PF, Morgan BP, Niet-feld W, Dirnagl U, Trendelenburg G. Membrane attack complex inhibitor CD59a protects against focal cerebral ischemia in mice. J Neuroinflamm , 2010, 7: 15.
[15] Uellner R, Zvelebil MJ, Hopkins J, Jones J, MacDougall LK, Morgan BP, Podack E, Waterfield MD, Griffiths GM. Perforin is activated by a proteolytic cleavage during bio-synthesis which reveals a phospholipid-binding C2 do-main. EMBO J, 1997, 16(24): 7287–7296.
[16] Voskoboinik I, Thia MC, Fletcher J, Ciccone A, Browne K, Smyth MJ, Trapani JA. Calcium-dependent plasma mem-brane binding and cell lysis by perforin are mediated through its C2 domain: A critical role for aspartate resi-dues 429, 435, 483, and 485 but not 491. J Biol Chem, 2005, 280(9): 8426–8434.
[17] Bolitho P, Voskoboinik I, Trapani JA, Smyth MJ. Apop-tosis induced by the lymphocyte effector molecule per-forin. Curr Opin Immunol, 2007, 19(3): 339–347.
[18] Pipkin ME, Lieberman J. Delivering the kiss of death: progress on understanding how perforin works. Curr Opin Immunol, 2007, 19(3): 301&nd
