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首页> 外文期刊>Journal of Virology >Formation and possible functions of alpha-putrescinylthymine in bacteriophage phi W-14 DNA: analysis of bacteriophage mutants with decreased levels of alpha-putrescinylthymine in their DNAs.
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Formation and possible functions of alpha-putrescinylthymine in bacteriophage phi W-14 DNA: analysis of bacteriophage mutants with decreased levels of alpha-putrescinylthymine in their DNAs.

机译：α-Putrescynynine在噬菌体PHI W-14 DNA中的形成和可能的功能：分析其DNA中α-普雷酮水平降低的噬菌体突变体。

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The DNA synthesized in the nonpermissive host by the noncomplementing mutants am36 and am42 of bacteriophage phi W-14 contains about half the wild-type level of alpha-putrescinylthymine (putThy) and a correspondingly greater level of thymine. The mechanisms whereby thymine nucleotides are excluded from replicating DNA are functional in both mutants because neither of them incorporates exogenous thymidine into DNA. It is proposed that (i) in wild-type phi W-14, the conversion of hydroxymethyluracil to putThy at the polynucleotide level is sequence specific, but that to thymine is nonspecific; and (ii) in the mutants, the sequence-specific recognition is impaired so that more thymine and less putThy are formed. The thymine-rich DNA can be packaged into phage particles. In the case of am42, the phage particles are morphologically indistinguishable from and have essentially the same polypeptide composition as wild-type particles. However, the DNA molecules they contain are about 11% shorter than those in wild-type phage, am42rev4, a revertant of am42, contains DNA with about 70% of the normal level of putThy; these molecules are about 3% shorter than wild-type DNA. The properties of am42 and am42rev4 are consistent with the suggestion that putThy facilitates the very tight packing of phi W-14 DNA (Scraba et al., Virology 124:152-160, 1983). It also appears that the putThy content of phi W-14 DNA can be reduced by no more than 30% without adversely affecting the production of viable progeny; for example, the burst size of am42rev4 is about 25% of that of the wild type.
机译：通过非符合突变体AM36和噬菌体PHI W-14中的非剪发宿主中合成的DNA含有约一半的野生型水平的α-putrescylthyne（Putthy）和相应更大水平的胸腺嘧啶。从复制DNA中排除胸腺嘧啶核苷酸的机制在两个突变体中都是功能性的，因为它们均未将外源胸苷掺入DNA中。提出（i）在野生型PHI W-14中，羟甲基脲对多核苷酸水平的羟甲基甲基脲转化为序列是特异性的，但胸腺嘧啶是非特异性的; （ii）在突变体中，抑制序列特异性识别，使得形成更多的胸腺嘧啶和更少的恶性。富含胸腺嘧啶的DNA可以包装成噬菌体颗粒。在AM42的情况下，噬菌体颗粒在形态上难以区分，并且具有基本上与野生型颗粒相同的多肽组合物。然而，它们含有的DNA分子比野生型噬菌体中的含量短约11％，AM42REV4含有AM42的回复剂，含有约70％的Putthy的DNA;这些分子比野生型DNA短约3％。 AM42和AM42REV4的性质与Putthy促进PHI W-14 DNA的非常紧密的包装的建议一致（Scraba等，病毒学124：152-160,1983）。似乎PHI W-14 DNA的POTTHY含量不能超过30％，而不会对可行的后代产生产生不利影响;例如，AM42REV4的突发大小约占野生类型的25％。

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