PDF(Pubmed)
Abstract：
Halophilic archaea (haloarchaea) are known to exhibit multiple chromosomes, with one main chromosome and one or several smaller secondary chromosomes or megaplasmids. Halorubrum lacusprofundi, a model organism for studying cold adaptation, exhibits one secondary chromosome and one megaplasmid that include a large arsenal of virus defense mechanisms. We isolated a virus (Halorubrum tailed virus DL1, HRTV-DL1) infecting Hrr. lacusprofundi, and present an in-depth characterization of the virus and its interactions with Hrr. lacusprofundi. While studying virus-host interactions between Hrr. lacusprofundi and HRTV-DL1, we uncover that the strain in use (ACAM34_UNSW) lost the entire megaplasmid and about 38% of the secondary chromosome. The loss included the majority of virus defense mechanisms, making the strain sensitive to HRTV-DL1 infection, while the type strain (ACAM34_DSMZ) appears to prevent virus replication. Comparing infection of the type strain ACAM34_DSMZ with infection of the laboratory derived strain ACAM34_UNSW allowed us to identify host responses to virus infection that were only activated in ACAM34_UNSW upon the loss of virus defense mechanisms. We identify one of two S-layer proteins as primary receptor for HRTV-DL1 and conclude that the presence of two different S-layer proteins in one strain provides a strong advantage in the arms race with viruses. Additionally, we identify archaeal homologs to eukaryotic proteins potentially being involved in the defense against virus infection.
摘要：
已知嗜盐古细菌（haloarchea）表现出多个染色体，具有一个主要染色体和一个或几个较小的次级染色体或巨型质粒。Halorubrumlacusprofundi，研究冷适应的模型生物，表现出一个次级染色体和一个包含大量病毒防御机制的巨型质粒。我们分离出一种感染Hrr的病毒（Halorubrum尾病毒DL1，HRTV-DL1）。lacusprofundi,并对该病毒及其与Hrr的相互作用进行了深入的表征。lacusprofundi.在研究Hrr之间的病毒-宿主相互作用时。lacusprofundi和HRTV-DL1，我们发现使用的菌株（ACAM34_UNSW）丢失了整个大质粒和约38％的次级染色体。损失包括大多数病毒防御机制，使菌株对HRTV-DL1感染敏感，而类型菌株（ACAM34_DSMZ）似乎阻止病毒复制。将ACAM34_DSMZ型菌株的感染与实验室衍生菌株ACAM34_UNSW的感染进行比较，使我们能够确定宿主对病毒感染的反应，这些反应仅在病毒防御机制丧失后在ACAM34_UNSW中被激活。我们确定了两种S层蛋白之一是HRTV-DL1的主要受体，并得出结论，一种菌株中两种不同S层蛋白的存在在与病毒的军备竞赛中提供了强大的优势。此外,我们鉴定了可能参与防御病毒感染的真核蛋白质的古细菌同源物。
