Translesion synthesis by DNA polymerase IV and its role in the replication of bacteria Escherichia coli

Genetički materijal organizama podložan je stalnim oštećenjima uzrokovanim endogenim i egzogenim čimbenicima. Postoje brojni mehanizmi koji brzo i točno popravljaju ovakva oštećenja. Međutim, ako je razina oštećenja toliko velika da mehanizmi koji ne rade greške nisu dovoljni da bi izvršili popravak, dolazi do indukcije SOS odgovora. Ova faza popravka uključuje sintezu preko lezije, tzv. translezijsku sintezu (TLS), a posredovana je translezijskim polimerazama. Jedna od pet polimeraza u bakteriji Escherichia coli je i DNA Pol IV. Na zaustavljenim replikacijskim rašljama, DNA polimeraza IV kompetira s polimeraznim podjedinicama DNA Pol III, da bi olakšala translezijsku replikaciju. U ovom seminaru opisana je indukcija SOS odgovora, svojstva Pol IV, lokalizacija i broj molekula u stanici te interakcije s replikativnom DNA Pol III. Mnogi radovi jasno predlažu modele za određene probleme vezane uz Pol IV. Međutim, postoje radovi koji iznose drugačija opažanja, ostavljajući time mnogo prostora za daljnja istraživanja.The genetic material of living organisms is suspectible to continuous damage caused by endogenous and exogenous factors. Various mechanisms exist that preform fast and accurate repair of such damage. However, if the level of damage is so vast that these high-fidelity mechanisms are not sufficient for repair, SOS response is induced. This phase of repair mechanism includes translesion synthesis (TLS), which is mediated by translesion polymerases. One of the five TLS polymerases in bacteria Escherichia coli is DNA Pol IV. At blocked replication fork, DNA Pol IV competes with subunits of replicative DNA Pol III in order to preform translesion synthesis. In this review, the induction of SOS response, properties, localization, number of Pol IV, as well as interactions with Pol III are discussed. Alhough a large number of research unequivocally suggest many models for the mentioned topics, there is a significant number of those which contradict these results thus leaving a space for the further research