Molecular Design and Functional Organization of the RecA Protein

McGrew, Dharia A.; Knight, Kendall L.

doi:10.1080/10409230390242489

Cited by 122 publications

(94 citation statements)

References 185 publications

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“…NTHI0729 and NTHI0083 encode homologues of RecA and RecN. RecA and RecN have important roles in the repair of DNA damage which have been extensively characterized in UV damage experiments in many organisms, including E. coli and H. influenzae (43,50,51,77,82). Further repair mechanisms are potentially afforded by the gene products of NTHI0493 and NTHI0495, which encode homologues of the cochaperone proteins HscA and HscB, respectively, and that have roles in iron-sulfur cluster assembly (2,31,78).…”

Section: Resultsmentioning

confidence: 99%

The OxyR Regulon in Nontypeable Haemophilus influenzae

et al. 2007

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Nontypeable Haemophilus influenzae (NTHi) is a gram-negative bacterium and a common commensal organism of the upper respiratory tract in humans. NTHi causes a number of diseases, including otitis media, sinusitis, conjunctivitis, exacerbations of chronic obstructive pulmonary disease, and bronchitis. During the course of colonization and infection, NTHi must withstand oxidative stress generated by insult due to multiple reactive oxygen species produced endogenously by other copathogens and by host cells. Using an NTHi-specific microarray containing oligonucleotides representing the 1821 open reading frames of the recently sequenced NTHi isolate 86-028NP, we have identified 40 genes in strain 86-028NP that are upregulated after induction of oxidative stress due to hydrogen peroxide. Further comparisons between the parent and an isogenic oxyR mutant identified a subset of 11 genes that were transcriptionally regulated by OxyR, a global regulator of oxidative stress. Interestingly, hydrogen peroxide induced the OxyR-independent upregulation of expression of the genes encoding components of multiple iron utilization systems. This finding suggested that careful balancing of levels of intracellular iron was important for minimizing the effects of oxidative stress during NTHi colonization and infection and that there are additional regulatory pathways involved in iron utilization.In the evolution of life, a delicate physiological balance has arisen to compensate for both an organism's need for oxygen and the attendant lethal consequences of oxygen's toxicity. For example, in the electron transport chain, electrons can be inadvertently transferred from redox-active proteins to oxygen, producing reactive oxygen species (ROS) such as superoxide and hydrogen peroxide (H 2 O 2 ). The effects of ROS on cells can then be exacerbated by the presence of free iron which, via the Fenton reaction, can react with H 2 O 2 to produce more highly reactive hydroxyl radicals (34, 40, 52). Within a host, this problem is compounded by the release of extracellular ROS by phagocytes, which again, can have deleterious effects on invading pathogens (13). Thus, bacteria have evolved an array of increasingly well-defined mechanisms to abrogate the effects of oxidative stress. Proteins involved in such processes include catalase, which decomposes H 2 O 2 , and members of both the AhpCF/TsaA family of alkylhydroperoxidases and the organic hydroperoxide resistance proteins (Ohr) that decompose organic peroxides. Also, DNA-binding ferritin-like proteins (Dps) sequester free iron and bind to DNA, thus protecting DNA from damage (27,33,45,53,59,60,67). In addition, many bacterial species possess genes encoding OxyR, a global regulator of antioxidant defenses (24, 66).Protection against oxidative stress is especially important to nontypeable Haemophilus influenzae (NTHi). NTHi is one of three bacterial commensal organisms, the others being Streptococcus pneumoniae and Moraxella catarrhalis, which can ascend a virus-compromised eustachian tube and caus...

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Section: Resultsmentioning

confidence: 99%

The OxyR Regulon in Nontypeable Haemophilus influenzae

et al. 2007

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“…In prokaryotes, the pathways for fork reactivation involve homologous recombination performed by RecA protein (Michel et al, 2004). RecA protein is a multifunctional enzyme that carries out both homologous recombinational repair and regulation of the SOS response (McGrew & Knight, 2003). Upon DNA damage, RecA protein binds to ssDNA and multimerizes into a helical nucleoprotein filament that stimulates autoproteolysis of the LexA repressor, which leads to derepression of more than 50 LexA-regulated genes (Courcelle et al, 2001;Fernández De Henestrosa et al, 2000;Friedberg et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

DNA compaction in the early part of the SOS response is dependent on RecN and RecA

Odsbu

Skarstad

2014

Microbiology

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The nucleoids of undamaged Escherichia coli cells have a characteristic shape and number, which is dependent on the growth medium. Upon induction of the SOS response by a low dose of UV irradiation an extensive reorganization of the nucleoids occurred. Two distinct phases were observed by fluorescence microscopy. First, the nucleoids were found to change shape and fuse into compact structures at midcell. The compaction of the nucleoids lasted for 10-20 min and was followed by a phase where the DNA was dispersed throughout the cells. This second phase lasted for~1 h. The compaction was found to be dependent on the recombination proteins RecA, RecO and RecR as well as the SOS-inducible, SMC (structural maintenance of chromosomes)-like protein RecN. RecN protein is produced in high amounts during the first part of the SOS response. It is possible that the RecN-mediated 'compact DNA' stage at the beginning of the SOS response serves to stabilize damaged DNA prior to recombination and repair.

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“…RecA is required for homologous recombination, contributes to the regulation of translesion synthesis, and participates in the SOS transcriptional response to DNA damage (7)(8)(9). In Escherichia coli, RecA binds ssDNA during the repair process, and formation of the RecA/ssDNA nucleoprotein filament (10) is required for activating RecA for its various roles in DNA repair (1).…”

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confidence: 99%

Replication is required for the RecA localization response to DNA damage in Bacillus subtilis

Simmons

Grossman

Walker

2007

Proc. Natl. Acad. Sci. U.S.A.

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In both prokaryotes and eukaryotes, proteins involved in DNA repair often organize into multicomponent complexes that can be visualized as foci in living cells. We used a RecA-GFP fusion to examine the subcellular cues that direct RecA-GFP to assemble as foci in response to DNA damage. We used two different methods to inhibit initiation of DNA replication and determined that DNA replication is required for the cell to establish RecA-GFP foci after exposure to DNA-damaging agents. Furthermore, use of endonuclease cleavage to generate a site-specific double-strand break demonstrated that the replication machinery (replisome) and DNA synthesis are required for assembly of RecA-GFP foci during repair of a double-strand break. We monitored the cellular levels of RecA and found that focus formation does not require further induction of protein levels, suggesting that foci result from a redistribution of existing protein to sites of damage encountered by the replisome. Taken together, our results support the model that existing RecA protein is recruited to ssDNA generated by the replisome at sites of DNA damage. These results provide insight into the mechanisms that the cell uses to recruit repair proteins to damaged DNA in living cells.replisome ͉ focus ͉ double-strand break

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Molecular Design and Functional Organization of the RecA Protein

Cited by 122 publications

References 185 publications

The OxyR Regulon in Nontypeable Haemophilus influenzae

The OxyR Regulon in Nontypeable Haemophilus influenzae

DNA compaction in the early part of the SOS response is dependent on RecN and RecA

Replication is required for the RecA localization response to DNA damage in Bacillus subtilis

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