A RECOMBINANT HEPATITIS-B CORE ANTIGEN POLYPEPTIDE WITH THE PROTAMINE-LIKE DOMAIN DELETED SELF-ASSEMBLES INTO CAPSID PARTICLES BUT FAILS TO BIND NUCLEIC-ACIDS
A RECOMBINANT HEPATITIS-B CORE ANTIGEN POLYPEPTIDE WITH THE PROTAMINE-LIKE DOMAIN DELETED SELF-ASSEMBLES INTO CAPSID PARTICLES BUT FAILS TO BIND NUCLEIC-ACIDS
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DOI：
10.1128/jvi.63.11.4645-4652.1989
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发表时间：
1989-11-01
影响因子：
5.4
通讯作者：
MILANESI, G
中科院分区：
文献类型：
--
作者：
GALLINA, A;BONELLI, F;MILANESI, G
我们已经在大肠杆菌中克隆了B型肝炎病毒的完整核心基因和它的截短版本，导致分别合成高水平的核心抗原等价多肽（r-p22）和e抗原等价多肽（r-p16）。然后，我们比较了两种多肽的结构和抗原特性，以及它们结合病毒核酸的能力。发现r-p16自组装成capture-like颗粒，当在电子显微镜下观察时，该capture-like颗粒看起来类似于由r-p22形成的颗粒。在r-p16颗粒中，二硫键将截短的多肽连接成二聚体，通过非共价相互作用组装在颗粒中。在r-p22衣壳中，进一步的二硫键，可以想象涉及r-p22多肽的羧基末端半胱氨酸，将二聚体连接在一起，将结构转化为共价闭合的晶格。鱼精蛋白样结构域至少部分暴露在r-p22颗粒的表面上，因为它可以被选择性蛋白水解。最后，r-p22，而不是r-p16，显示结合天然和变性的DNA以及RNA。综上所述，这些结果表明，核心多肽中的鱼精蛋白样结构域是一个核酸结合结构域，并且是正确折叠和组装的氨基末端和中心区域。
We have cloned in Escherichia coli both the complete core gene of hepatitis B virus and a truncated version of it, leading to the synthesis of high levels of a core-antigen-equivalent polypeptide (r-p22) and of an e-antigen-equivalent polypeptide (r-p16), respectively. We then compared the structural and antigenic properties of the two polypeptides, as well as their ability to bind viral nucleic acids. r-p16 was found to self-assemble into capsid-like particles that appeared similar, when observed under the electron microscope, to those formed by r-p22. In r-p16 particles, disulfide bonds linked the truncated polypeptides in dimers, assembled in the particle by noncovalent interactions. In r-p22 capsids, further disulfide bonds, conceivably involving the carboxy-terminal cysteines of r-p22 polypeptides, joined the dimers together, converting the structure into a covalently closed lattice. The protamine-like domain was at least partly exposed on the surface of r-p22 particles, since it was accessible to selective proteolysis. Finally, r-p22, but not r-p16, was shown to bind native and denatured DNA as well as RNA. Taken together, these results suggest that the protamine-like domain in core polypeptides is a nucleic acid-binding domain and is dispensable for the correct folding and assembly of amino-terminal and central regions.