Hermoso J M, Salas M
Proc Natl Acad Sci U S A. 1980 Nov;77(11):6425-8. doi: 10.1073/pnas.77.11.6425.
To investigate the role of protein p3 in bacteriophage phi 29 initiation of replication, we have studied the nature of the covalent linkage between protein p3 and phi 29 DNA. The protein-DNA compound was digested with micrococcal nuclease and pronase resulting in a nucleotidyl-peptide that was further digested by alkaline phosphatase and snake venom phosphodiesterase yielding 5'-dAMP. The DNA-protein linkage is sensitive to alkali. Treatment of the nucleotidyl-peptide with 0.1 M NaOH at 37 degrees C for 3 hr after phosphatase digestion released 5'-dAMP. Hydrolysis of the nucleotidyl-peptide with 5.8 M HCl at 110 degrees C for 90 min yielded O-phosphoserine. These results, together with the sensitivity of the DNA-protein linkage to snake venom phosphodiesterase and its resistance to hydroxylamine, indicate that protein p3 is covalently linked to phi 29 DNA through a phosphoester bond between L-serine and 5'-dAMP, namely a O,5'-deoxyadenylyl-L-serine bond.
为了研究蛋白质p3在噬菌体φ29复制起始中的作用，我们研究了蛋白质p3与φ29 DNA之间共价连接的性质。用微球菌核酸酶和链霉蛋白酶消化蛋白质-DNA复合物，产生一种核苷酸肽，该核苷酸肽再经碱性磷酸酶和蛇毒磷酸二酯酶进一步消化，产生5'-dAMP。DNA-蛋白质连接对碱敏感。磷酸酶消化后，在37℃用0.1 M NaOH处理核苷酸肽3小时，释放出5'-dAMP。在110℃用5.8 M HCl水解核苷酸肽90分钟，产生O-磷酸丝氨酸。这些结果，连同DNA-蛋白质连接对蛇毒磷酸二酯酶的敏感性及其对羟胺的抗性，表明蛋白质p3通过L-丝氨酸与5'-dAMP之间的磷酸酯键，即O,5'-脱氧腺苷酰-L-丝氨酸键，与φ29 DNA共价连接。
