Small Prokaryotic DNA-Binding Proteins Protect Genome Integrity throughout the Life Cycle

Genomes of all organisms are persistently threatened by endogenous and exogenous assaults. Bacterial mechanisms of genome maintenance must provide protection throughout the physiologically distinct phases of the life cycle. Spore-forming bacteria must also maintain genome integrity within the dormant endospore. The nucleoid-associated proteins (NAPs) influence nucleoid organization and may alter DNA topology to protect DNA or to alter gene expression patterns. NAPs are characteristically multifunctional; nevertheless, Dps, HU and CbpA are most strongly associated with DNA protection. Archaea display great variety in genome organization and many inhabit extreme environments. As of yet, only MC1, an archaeal NAP, has been shown to protect DNA against thermal denaturation and radiolysis. ssDNA are intermediates in vital cellular processes, such as DNA replication and recombination. Single-stranded binding proteins (SSBs) prevent the formation of secondary structures but also protect the hypersensitive ssDNA against chemical and nuclease degradation. Ionizing radiation upregulates SSBs in the extremophile Deinococcus radiodurans.

Automated summary

The integrity of genomes is constantly threatened by internal and external attacks, and bacteria and archaea have different mechanisms to protect DNA. Nucleoid-associated proteins can influence DNA structure and have multiple functions, with Dps, HU, and CbpA being most closely associated with DNA protection. Single-stranded binding proteins can protect single-stranded DNA from degradation.