DNA Recognition during DNA Packaging by the Lambda-like Bacteriophages: Sites and Proteins

在大的双链DNA病毒中，如疱疹病毒和尾噬菌体，病毒DNA通过包装酶（称为末端酶）和病毒DNA中的特异性识别位点的相互作用被识别用于包装。在类噬菌体中，这些识别位点位于大约200 bp长的称为cos的DNA片段中。cos含有几个亚位点，包括cosB，末端酶结合位点，和cosN，末端酶切割DNA以产生单位长度DNA分子的位点。本研究探讨了一个新发现的位于cosN和cosB之间的子位点的功能。将确定新位点包括DNA弯曲的可能性。将研究在DNA包装的开始和/或结束时是否需要新的位点。在典型的类噬菌体λ的cos中的末端酶结合位点是大而复杂的，具有三个末端酶结合位点。由于这种复杂性，λ的末端酶在cos上形成复杂的DNA-蛋白质复合物。噬菌体N15是一种类噬菌体病毒。N15的末端酶结合位点非常简单--只有一个末端酶结合位点。一个主要的问题是N15末端酶是否形成复杂的DNA-蛋白质复合物，或者N15识别是否与λ识别根本不同。N15末端酶如何结合N15的cos的实验将为dsDNA病毒中的DNA识别提供重要的见解。这个研究项目将提供具有挑战性的研究经验，从不同背景的几个本科生。该工作对于理解dsDNA病毒如何包装病毒DNA具有普遍意义。

In the large double-stranded DNA viruses, such as the herpes viruses and the tailed bacteriophages, viral DNA is recognized for packaging thru the interactions of a packaging enzyme, called terminase, and specific recognition sites in the viral DNA. In the lambda-like bacteriophages, these recognition sites are located in an approximately 200 bp-long DNA segment called cos. cos contains several subsites, including cosB, the terminase binding site, and cosN, the site where terminase cuts the DNA to make unit-length DNA molecules. This research investigates the function of a newly-discovered subsite located between cosN and cosB. The possibility that the new site includes a DNA bend will be determined. Whether the new site is needed at the start and/or the end of DNA packaging will be studied. The terminase binding site in the cos of the paradigm lambda-like bacteriophage, lambda, is large and complex, with three binding sites for terminase. Because of this complexity, the terminase of lambda forms a complicated DNA-protein complex on cos. Bacteriophage N15 is a lambda-like virus. The terminase binding site for N15 is very simple -- there is only one terminase binding site. A major question is whether N15 terminase forms a complicated DNA-protein complex, or whether N15 recognition differs fundamentally from lambda recognition. Experiments on how N15 terminase binds the cos of N15 will give important insights into DNA recognition in the dsDNA viruses. This research project will provide challenging research experiences to several undergraduates from diverse backgrounds. The work is of general significance for understanding how dsDNA viruses package viral DNA.