Overview of E. coli single stranded binding protein SSB and its cooperativity.

E. coli single stranded binding protein (Eco SSB) is encoded by ssb gene which consists of 534 bp in coding region. Product of ssb gene contains 177 amino acids with a molecular weight of 18,9 kDa. In solution, Eco SSB forms a tetramer as the active form (sometimes be viewed as a “dimer of dimers”). SSB is known to tightly bind single stranded DNA (ssDNA) with very high affinity and protects that ssDNA from nuclease, reannealing or secondary formation …  or keeps ssDNA intermediates, therefore involved Continue Reading →

DNA Polymerase III Holoenzyme

Pol III Holoenzyme is a big molecule that consists of 10 different subunits. Three subunits alpha, epsilon and theta form the core and there are 2 cores in a Pol III Holo enzyme complex that linked by tau subunit. Each core is responsible for leading and lagging synthesis. The gamma complex (clamp loader) is composed of gamma, delta, delta prime, chi and psi subunits; take in charge in loading beta clamp onto primed DNA. The complex consist of two cores and the gamma complex is called as Polymerase III*. When beta clamp is added to each Continue Reading →