Nucleotides regulate the conformational state of the small terminase subunit from bacteriophage lambda: implications for the assembly of a viral genome-packaging motor.
Nucleotides regulate the conformational state of the small terminase subunit from bacteriophage lambda: implications for the assembly of a viral genome-packaging motor.
复制标题
核苷酸调节 lambda 噬菌体小终止酶亚基的构象状态：对病毒基因组包装马达组装的影响。
DOI：
10.1021/bi050333e
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发表时间：
2005
期刊：
影响因子：
--
通讯作者：
Catalano,CarlosE
中科院分区：
文献类型：
--
作者：
Gaussier,Helene;Ortega,MarcosE;Maluf,NasibK;Catalano,CarlosE
Terminase enzymes are responsible for “packaging” of viral DNA into a preformed procapsid. Bacteriophage lambda terminase is composed of two subunits, gpA and gpNu1, in a gpA1·gpNu12holoenzyme complex. The larger gpA subunit is responsible for preparation of viral DNA for packaging, and is central to the packaging motor complex. The smaller gpNu1 subunit is required for site-specific assembly of the packaging motor on viral DNA. Terminase assembly at the packaging initiation site is regulated by ATP binding and hydrolysis at the gpNu1 subunit. Characterization of the catalytic and structural interactions between the DNA and nucleotide binding sites of gpNu1 is thus central to our understanding of the packaging motor at the molecular level. The high-resolution structure of the DNA binding domain of gpNu1 (gpNu1-DBD) was recently determined in our lab [de Beer, T., et al. (2002)Mol. Cell9, 981−991]. The structure reveals the presence of a winged−helix−turn−helix DNA binding motif, but the location of the ATPase catalytic site in gpNu1 remains unknown. In this work, nucleotide binding to the gpNu1-DBD was probed using acrylamide fluorescence quenching and fluorescence-monitored ligand binding studies. The data indicate that the minimal DBD dimer binds both ATP and ADP at two equivalent but highly cooperative binding sites. The data further suggest that ATP and ADP induce distinct conformations of the dimer but do not affect DNA binding affinity. The implications of these results with respect to the assembly and function of a terminase DNA-packaging motor are discussed.
