Wu Xiao-Jun, Sabat Greg, Brown James F, Zhang Mengzi, Taft Andrew, Peterson Nathan, Harms Amy, Yoshino Timothy P
Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin, Madison, WI 53706, United States.
Mol Biochem Parasitol. 2009 Mar;164(1):32-44. doi: 10.1016/j.molbiopara.2008.11.005. Epub 2008 Nov 27.
Free-living miracidia of Schistosoma mansoni, upon penetration of the their snail intermediate host, undergo dramatic morphological and physiological changes as they transform to the parasitic sporocyst stage. During this transformation process, developing larvae release a diverse array of proteins, herein referred to as larval transformation proteins (LTPs), some of which are postulated to serve a parasite protective function. In the present study, nanoLC-tandem MS analysis was performed on all proteins represented in entire 1-dimensional SDS-PAGE-separated samples in order to gain a more comprehensive picture of the protein constituents associated with miracidium-to-sporocyst transformation and thus, their potential role in influencing establishment of intramolluscan infections. Of 127 proteins with sufficient peptide/sequence information, specific identifications were made for 99, while 28 represented unknown or hypothetical proteins. Nineteen percent of identified proteins possessed signal peptides constituting a cohort of classical secretory proteins, while 22% were identified as putative nonclassically secreted leaderless proteins based on SecretomeP analysis. Proteins comprising these groups consisted mainly of proteases/protease inhibitors, small HSPs, redox/antioxidant enzymes, ion-binding proteins including those with anti-oxidant Fe-binding activities (ferritins, heme-binding protein), and venom allergen-like (VAL) proteins. A polyclonal antibody generated against whole LTPs recognized proteins primarily associated with the cilia, ciliated epidermal plates and intercellular ridges of miracidia and the tegument of fully transformed sporocysts, identifying these structures as sources of a subset of LTPs. Thus lysis of plates and/or leakage during formation of the sporocyst syncytium likely represent significant contributors to the overall LTP makeup, especially identified nonsecretory proteins. However, as plate release/degradation and tegument formation are part of the normal developmental process, all LTPs regardless of tissue origin, would be expected at the parasite-host interface upon infection. This study significantly expands the repertoire of LTPs associated with larval transformation and identifies several, e.g., those involved in stress responses, proteolysis/inhibition, antioxidant and detoxication, and immune modulation, that may play a parasite protective role during this crucial period of transition.
曼氏血吸虫的自由生活毛蚴在侵入其螺蛳中间宿主后，在转变为寄生性胞蚴阶段时会经历显著的形态和生理变化。在这个转变过程中，发育中的幼虫会释放出各种各样的蛋白质，在此称为幼虫转变蛋白（LTPs），其中一些被推测具有寄生虫保护功能。在本研究中，对一维SDS-PAGE分离样品中所代表的所有蛋白质进行了纳升液相色谱-串联质谱分析，以便更全面地了解与毛蚴向胞蚴转变相关的蛋白质成分，从而了解它们在影响螺内感染建立中的潜在作用。在127个具有足够肽段/序列信息的蛋白质中，有99个得到了特异性鉴定，而28个代表未知或假设的蛋白质。19%的已鉴定蛋白质具有信号肽，构成了一组经典分泌蛋白，而根据SecretomeP分析，22%被鉴定为推定的非经典分泌无信号肽蛋白。这些组中的蛋白质主要包括蛋白酶/蛋白酶抑制剂、小分子热休克蛋白、氧化还原/抗氧化酶、离子结合蛋白，包括那些具有抗氧化铁结合活性的蛋白（铁蛋白、血红素结合蛋白），以及类毒液过敏原（VAL）蛋白。针对整个LTPs产生的多克隆抗体识别主要与毛蚴的纤毛、纤毛表皮板和细胞间嵴以及完全转变的胞蚴的体表相关的蛋白质，将这些结构确定为LTPs子集的来源。因此，在胞蚴合胞体形成过程中板层的裂解和/或渗漏可能是总体LTP组成的重要贡献者，特别是已鉴定的非分泌蛋白。然而，由于板层释放/降解和体表形成是正常发育过程的一部分，预计在感染时所有LTPs无论组织来源如何都会出现在寄生虫-宿主界面。本研究显著扩展了与幼虫转变相关的LTPs库，并鉴定出几种可能在这个关键转变期发挥寄生虫保护作用的蛋白，例如那些参与应激反应、蛋白水解/抑制、抗氧化和解毒以及免疫调节的蛋白。
