Porcek Natalia B, Parent Kristin N
Michigan State University Department of Microbiology and Molecular Genetics, East Lansing, MI 48824, USA; Michigan State University Department of Biochemistry and Molecular Biology, East Lansing, MI 48824, USA.
Michigan State University Department of Biochemistry and Molecular Biology, East Lansing, MI 48824, USA.
J Mol Biol. 2015 May 22;427(10):1964-76. doi: 10.1016/j.jmb.2015.03.012. Epub 2015 Mar 24.
Many viruses, including bacteriophage, have the inherent ability to utilize several types of proteinaceous receptors as an attachment mechanism to infect cells, yet the molecular mechanisms that drive receptor binding have not been elucidated. Using bacteriophage Sf6 and its host, Shigella flexneri, we investigated how Sf6 utilizes outer membrane protein A (OmpA) for infection. Specifically, we identified that surface loops of OmpA mediate Shigella infection. We further characterized which residues in the surface loops are responsible for Sf6 binding and productive infection using a combination of in vivo and in vitro approaches including site-directed mutagenesis, phage plaque assays, circular dichroism spectroscopy, and in vitro genome ejection assays. Our data indicate that Sf6 can productively interact with other bacterial OmpAs as long as they share homology in loops 2 and 4, suggesting that these loops may determine host specificity. Our data provide a model in which Sf6 interacts with OmpA using the surface of the protein and new insights into viral attachment through binding to membrane protein receptors.
许多病毒，包括噬菌体，都具有利用多种蛋白质受体作为附着机制来感染细胞的内在能力，但驱动受体结合的分子机制尚未阐明。利用噬菌体Sf6及其宿主弗氏志贺菌，我们研究了Sf6如何利用外膜蛋白A（OmpA）进行感染。具体而言，我们确定OmpA的表面环介导志贺菌感染。我们进一步利用体内和体外相结合的方法，包括定点诱变、噬菌斑测定、圆二色光谱和体外基因组释放测定，来表征表面环中的哪些残基负责Sf6结合和有效感染。我们的数据表明，只要其他细菌的OmpA在环2和环4中具有同源性，Sf6就能与它们有效相互作用，这表明这些环可能决定宿主特异性。我们的数据提供了一个模型，其中Sf6利用蛋白质表面与OmpA相互作用，并通过与膜蛋白受体结合为病毒附着提供了新的见解。
