FUNCTIONAL HOMOLOGY BETWEEN ACTIVE BAX AND BACTERIOPHAGE HOLIN

这个子项目是利用资源的许多研究子项目之一。 由NIH/NCRR资助的中心拨款提供。对子项目的主要支持 子项目的首席调查员可能是由其他来源提供的， 包括美国国立卫生研究院的其他来源。为子项目列出的总成本可能 表示该子项目使用的中心基础设施的估计数量， 不是由NCRR赠款提供给次级项目或次级项目工作人员的直接资金。 细胞凋亡是一种细胞死亡程序，对于协调多细胞生物体的发育和维持组织内环境的稳定至关重要。细胞凋亡的异常阻断与肿瘤的发生发展有关。另一方面，大多数癌症治疗药物是通过诱导癌细胞凋亡来发挥作用的。线粒体依赖途径是导致细胞凋亡的主要途径，在线粒体外膜通透性(MOMP)过程中主要受Bcl2家族蛋白的调节。Bax/Bak依赖的MOMP在细胞凋亡过程中的作用机制尚不清楚。我们的初步研究发现，Bax或Bak的活性突变体是细菌细胞裂解和细胞死亡的有效诱导剂。更重要的是，它们的功能类似于霍林噬菌体。我们的假设是，活性Bax起霍林的作用，导致细菌膜损伤。在目标1中，我们建议检查BAX的结构元件，这些结构元件介导细菌裂解活性。在目标2中，我们建议研究同源齐聚对活性Bax的细菌裂解活性的要求。在目标3中，我们建议检测活性Bax的细菌内膜定位，并确定Bax的细菌膜靶向序列。在目标4中，我们建议测试Lamda噬菌体中Holin的功能和遗传替换。这些研究有望将MOMP与霍林介导的细菌膜空洞形成从机械上联系起来。如果成功，这项工作将为MOMP的机制提供新的见解，并建立细菌作为研究细胞凋亡的强大模型系统。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Apoptosis is a cell death program critical for orchestrating development and maintaining tissue homeostasis of multi-cellular organisms. Aberrant blockade of apoptosis is associated the development and progression of cancer. On the other hand, most cancer therapeutics function by inducing apoptosis in cancer cells. The mitochondria-dependent pathway is primarily responsible for apoptosis, and is largely regulated by the Bcl-2 family proteins at the step of mitochondrial outer membrane permeabilization (MOMP). The mechanism of Bax/Bak-dependent MOMP during apoptosis remains poorly understood. Our preliminary studies found that active mutants of Bax or Bak are potent inducers of bacterial cell lysis and cell death. More importantly, they function in a fashion similar to that of bacteriophage holin. Our hypothesis is that active Bax functions as a holin to cause bacterial membrane lesions. In Aim 1, we propose to examine the structural elements of Bax that are mediating the bacterial lysis activity. In Aim 2, we propose to examine the requirement of homo-oligomerization for the bacterial lysis activity of active Bax. In Aim 3, we propose to examine the bacterial inner membrane localization of active Bax, and identify the bacterial membrane targeting sequence of Bax. In Aim 4, we propose to test the functional and genetic replacement of holin in lamda bacteriophage. These studies are expected to mechanistically linked MOMP to holin-mediated hole formation in the bacterial membrane. If successful, this work will provide novel insights into the mechanism of MOMP, and establish bacteria as a powerful model system for the study of apoptosis.