Posts Tagged ‘RT’

Reverse transcriptase (RT), uma enzima para replicacao de retroviruses, esta entre as mais abundantes proteinas neste planeta, e merece uma pesquisa

quinta-feira, maio 17th, 2018


RT and Rnase H of Retroviruses and Retrovirus-Like Elements

The discovery of the reverse transcriptase (RT), initially described as replication enzyme of retroviruses in 1970 (Baltimore, 1970; Temin and Mizutani, 1970), was so unexpected that it was awarded a Nobel prize in 1975. Shortly after the RT, the retroviral ribonuclease H (RNase H) was identified in retrovirus particles as essential component for the replication of viral RNA via an RNA-DNA hybrid intermediate to double stranded DNA (dsDNA) (Mölling et al., 1971; Hansen et al., 1988; Tisdale et al., 1991). Historically, the RNase H has often been considered as part of the RT in retroviruses. However, the enzyme has its proper role, impact on evolution and importance for the degradation of nucleic acids in various biological processes. Similarly, the RT is of much more general importance than just replicating retroviral genomes. One prominent example is the telomerase, the RT or TERT, that elongates chromosomal ends in embryonic tissue and stem cells. Here, RNase H activity is not involved, since the template RNA needs to be copied repeatedly. Both the RT and the RNase H are among the most abundant proteins on our planet (Ma et al., 2008; Caetano-Anollés et al., 2009; Majorek et al., 2014).

“… Contrary to Francis Crick’s ‘central dogma’ from 1958 the RT, in concert with the RNase H, allows for the flow of information to occur from RNA to DNA. This was regarded as the reverse orientation, a historical view rooted in the discovery that DNA was the carrier of genetic information (Figure 1A).”

Ok, denominaram a proteina de “reverse transcricao” porque ao inves do fluxo de informacao ir do DNA para o RNA para este fazer as proteinas, o fluxo vai ao reverse, partindo do RNA para o DNA… mas como sao informacoes sobre virus, e as vezes o DNA incorpora estas informacoes, elas podem entrar na evolucao. Varias doencas, como a hepatite, podem ser causadas por esta invasao de informacoes de virus no DNA. E’ como o arabe jovem descuidado que deixa e aceita entrar informacoes falsas de falsas religioes e por fim acabam se tornando um homem-bomba se suicidando. Assim faz o DNA… 

(Continuar lendo e pesquisando)