Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
Virology. 2012 Dec 20;434(2):242-50. doi: 10.1016/j.virol.2012.08.031. Epub 2012 Sep 12.
80α is a temperate, double-stranded DNA bacteriophage of Staphylococcus aureus that can act as a "helper" for the mobilization of S. aureus pathogenicity islands (SaPIs), including SaPI1. When SaPI1 is mobilized by 80α, the SaPI genomes are packaged into capsids that are composed of phage proteins, but that are smaller than those normally formed by the phage. This size determination is dependent on SaPI1 proteins CpmA and CpmB. Here, we show that co-expression of the 80α capsid and scaffolding proteins in S. aureus, but not in E. coli, leads to the formation of procapsid-related structures, suggesting that a host co-factor is required for assembly. The capsid and scaffolding proteins also undergo normal N-terminal processing upon expression in S. aureus, implicating a host protease. We also find that SaPI1 proteins CpmA and CpmB promote the formation of small capsids upon co-expression with 80α capsid and scaffolding proteins in S. aureus.
80α 是一种温和的、双链 DNA 金黄色葡萄球菌噬菌体，可作为金黄色葡萄球菌致病岛（SaPIs），包括 SaPI1 移动的“助手”。当 SaPI1 被 80α 移动时，SaPI 基因组被包装到衣壳中，这些衣壳由噬菌体蛋白组成，但比噬菌体通常形成的衣壳小。这种大小的确定取决于 SaPI1 蛋白 CpmA 和 CpmB。在这里，我们表明，80α 衣壳和支架蛋白在金黄色葡萄球菌中的共表达，但不在大肠杆菌中，导致形成与原衣壳相关的结构，表明需要宿主共因子进行组装。衣壳和支架蛋白在金黄色葡萄球菌中的表达也经历正常的 N 端加工，暗示宿主蛋白酶的参与。我们还发现，SaPI1 蛋白 CpmA 和 CpmB 促进小衣壳的形成，当与 80α 衣壳和支架蛋白在金黄色葡萄球菌中共表达时。
