Abstract
AbstractHow can an antiparallel DNA (deoxyribonucleic acid) strand be duplicated by aDNA polymerasethat synthesises DNA in only one direction? This paradox of DNA synthesis on the lagging strand was dissolved by discovery of Okazaki fragments. The major components of the bacterial replication fork includereplicative helicase,primaseandDNA polymerase. The loading ofreplicative helicase,DnaB, is the most critical step for assembly of a primosome, a protein complex responsible for duplex unwinding and primer RNA (ribonucleic acid) synthesis at the replication fork.DNA polymerasemay be an asymmetric dimer, each of which may concurrently synthesise leading or lagging strand. Several different modes of primosome assembly have been identified in bacteria. AtoriC(origin of chromosome),DnaA‐dependent primosome is assembled for initiation of a round of DNA replication, whereasPriA‐dependent primosome is assembled at stalled replication forks to facilitate replication restart.Key Concepts:Initiation of DNA replication: DNA replication is initiated by the initiator protein, which specifically recognises and binds to the origin sequence and recruits other primosome components including a DNA helicase.Leading and lagging strands: Leading strand is the one in which the direction of DNA chain elongation and overall fork movement is the same and lagging strand is the one in which they are opposite.Replicative helicase: An enzyme which catalyses continuous unwinding of the parental duplex DNA at the replication fork.Replication fork: The site of DNA replication where two replicating single‐stranded DNA separates.Primer RNA: A short stretch of RNA, the 3′‐terminus of which is utilised by DNA polymerases for DNA elongation.Primosome: A name given to the protein complex capable of duplex DNA unwinding and primer RNA synthesis at the replication fork.Stalled replication fork: A replication fork the movement of which is blocked by internal and external ‘replication stress’ including DNA damages and depletion of nucleotide precursors.Replication restart: The process of reassembly of primosome at a stalled replication fork to resume DNA chain elongation.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
