SSB. single-stranded binding protein

SSB Single-stranded binding protein (helix destabilizing)... 

Figure 11.5 Simultaneous synthesis of leading and lagging templates. P = RNA primer SSB = single-stranded binding protein.

The amplification of genetic information, i.e., the replication of parent DNA molecules, is achieved by means of an entire set of enzymes. The major players are a DNA-gyrase for unwinding of the double helix, proteins to separate the two antiparallel DNA strands at the replicational junction, single-stranded binding proteins (SSB) that prevent the... 

The E. coli single-strand binding protein, another helix-destabilizing protein that is usually called simply SSB, is a tetramer of 18.5-kDa subunits.265,3,2,313 It is essential to DNA replication. About 35 nucleotides may bind to each tetramer.314 The situation is not as clear in eukaryotes where DNA is largely coiled around histones in the nucleosomes. Several singlestrand binding proteins have been identified,315 but the need for SSB proteins in eukaryotic nuclear replication is uncertain.316 A human mitochondrial SSB resembles that of E. coli.317... 

Single-strand binding protein (SSB) is found in abundance in E. coli, and it is believed to be bound in mass at the replication fork. This fact and other evidence described later on indicate that it plays an important role at the growth fork. 

Know the roles of DNA polymerase I, II, III, and eukaryotic DNA polymerases, the roles of primers, helicases, single-stranded binding proteins (SSB), topoisomerases (gyrase), ligases, primase, and RNA polymerases, and the differences between the leading and lagging strands of DNA. 

Single-strand binding protein (SSB) prevents the helix from simply zipping back up once the helicase has passed. As shown in Figure 22.7, SSB, which has an extremely high affinity for single-strand DNA, is primarily needed on... 

Single-stranded binding proteins (SSBs) prevent the strands from rejoining and strongly stimulate helicase activity. 

The low torsion constant at a = —0.025 is very similar to that observed in a supercoiled pBR322 that was partially relaxed by saturation binding of Escherichia coli single-strand binding (ssb) protein, and which persisted for over a month.(56) It is also similar to that recently inferred from an in vivo assay based on variation in repression efficiency with size of a putative DNA loop.(234) Indeed, it appears that anomalously low torsion constants may be universally encountered in the course of either partial or complete relaxation of supercoiled DNAs, regardless of whether the superhelix density is reduced by action of topoisomerase I, binding of ssb protein, binding of intercalated... 

StabiUzation of unwound template strands Single-stranded DNA-binding protein (SSB) Single-stranded DNA-binding protein (SSB)... 

Figure 11-2. The prokaryotic DNA replication fork. A schematic representation of semi-conservative replication of DNA by different mechanisms on the leading and lagging strands by DNA polymerase III (DNA pol III) is shown. Other enzymes and accessory proteins that participate in initiation, elongation, and ligation phases of the process are indicated, with DNA pol I depicted as having just dissociated from a completed Okasaki fragment. SSBs, single-stranded DNA binding proteins.

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