| 词条 | Enterobacteria phage Qbeta |
| 释义 |
| image = Bacteriophage Qβ attached to sex pilus of E. coli.jpg | virus_group = iv | familia = Leviviridae | genus = Allolevivirus | species = Bacteriophage Qβ }}Bacteriophage Qβ has a single-stranded RNA linear genome packaged in an icosahedral capsid with a diameter of 25 nm. Its host is Escherichia coli. Qβ enters its host cell after binding to the side of the F pilus.[1] GeneticsThe genome of Qβ is 4215 nucleotides long. The genome has three open reading frames and encodes four proteins: A1, A2, CP and qβ replicase. The genome is highly structured, which regulates gene expression and protects the genome from host RNases.[1] Protein A2A2 is called the maturation protein due to its lysis activity. One copy of A2 is present per virion. The mechanism of lysis is similar to that of penicillin; A2 inhibits the formation of peptidoglycan by inhibiting the enzyme UDP-N-acetylglucosamine 1-carboxyvinyltransferase (MurA), which catalyzes the first committed step of peptidoglycan synthesis. A2 also functions in host cell recognition and cell entry. When A2 binds to the sex pilus of the bacterium, A2 cleaves and forms a pore into the host. RNA PolymeraseThe RNA polymerase that replicates both the plus and minus RNA strands is a complex of four proteins: the beta subunit (replicase) is encoded by the phage, while the other three subunits are encoded by the bacterial genome: alpha subunit (ribosomal protein S1), gamma subunit (EF-Tu), and delta subunit (EF-Ts).[2] Experiments{{Main|Spiegelman's monster}}RNA from Bacteriophage Qβ was used by Sol Spiegelman in experiments that favored faster replication, and thus shorter strands of RNA. He ended up with Spiegelman's Monster, an RNA chain of only 218 nucleotides that is also self-replicating. References1. ^1 {{cite journal |author=Kashiwagi A, Yomo T |title=Ongoing phenotypic and genomic changes in experimental coevolution of RNA bacteriophage Qβ and Escherichia coli |journal=PLoS Genetics |volume=7 |issue=8 |pages=e1002188 |date=August 2011 |pmid=21829387 |pmc=3150450 |doi=10.1371/journal.pgen.1002188 |url=}} {{Taxonbar|from=Q4840022}}2. ^{{cite book |last=van Duin |first=J. |last2=Tsareva |first2=N. |chapter=Single-stranded RNA phages. Chapter 15 |pages=175–196 |editor-last=Calendar |editor-first=R. L. |title=The Bacteriophages |edition=Second |publisher=Oxford University Press |year=2006 |isbn=0195148509 }} 1 : Leviviridae |
| 随便看 |
|
开放百科全书收录14589846条英语、德语、日语等多语种百科知识，基本涵盖了大多数领域的百科知识，是一部内容自由、开放的电子版国际百科全书。