Data of the RT-qPCR graphs presented in S3 Fig.

In the arms race between a pathogen and the host, the defense mechanisms of the host cell, including the ubiquitin system, are often counteracted by bacteria. Simkania negevensis (Sne), an obligate intracellular Chlamydia-like bacterium connected with respiratory diseases, possesses numerous deubiquitinases, but not much is known about its other ubiquitin-modifying enzymes. Sne infects a wide range of hosts, developing inside a tubular vacuole in close contact with the host endoplasmic reticulum (ER) and mitochondria. Our study describes an uncharacterized Sne ubiquitin E3 RING-ligase (SNE_A12920 or SneRING), which primarily generates K63- and K11-linked ubiquitin chains and preferentially interacts with UbcH5b and UBE2T E2 enzymes. SneRING is expressed upon infection of various human cell lines, as well as amoebae. We show that a portion of the expressed SneRING co-localizes with mitochondria and ER and that the SneRING interactome includes mitochondrial and ER proteins involved in organelle morphology and stress response. Our work offers an initial characterization of a bacterial RING ligase potentially involved in the host cell remodeling to accommodate the unique intracellular lifestyle of Sne.

在病原体与宿主的军备竞赛中，宿主细胞的防御机制（包括泛素系统）常会被细菌拮抗。内夫西蒙菌（Simkania negevensis，简称Sne）是一种与呼吸道疾病相关的专性胞内衣原体样细菌，其拥有多种去泛素化酶，但目前对其其他泛素修饰酶的了解甚少。该菌可感染多种宿主，在与宿主内质网（Endoplasmic Reticulum, ER）和线粒体紧密接触的管状液泡内增殖。本研究对一种未被表征的Sne源泛素E3 RING型连接酶（SNE_A12920，又称SneRING）进行了初步分析，该酶主要生成K63位连接与K11位连接的泛素链，并优先与UbcH5b及UBE2T这两种E2酶发生相互作用。SneRING在感染多种人类细胞系及变形虫时均会表达。我们发现，部分表达的SneRING可与线粒体和内质网共定位，且SneRING的互作组包含参与细胞器形态维持与应激反应的线粒体及内质网蛋白。本研究首次对一种细菌RING连接酶进行了表征，该酶可能参与宿主细胞重塑以适配Sne独特的胞内寄生生活方式。