Biomaterial Database

[Chemically methylated DNA repair in Escherichia coli--the role of alkB protein]. 2006

Celina Janion

Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 5A Pawińskiego St., 02-106 Warszawa, Poland. celina@ibb.waw.pl

Methylating agents belong to mutagens occurring most frequently in our environment. They methylate mainly the nitrogen bases in DNA and RNA, affecting their functions. In E. coli the alkylated bases are repaired by proteins and enzymes either permanently present in the cells (Ogt, Ada) or produced transiently (Ada, AlkB, AlkA, Aid), after induction of the Ada defence system. Alkylating agents induce also the SOS system, which enhances the synthesis of about 40 proteins, including those participating in recombination, replication and mutagenesis of DNA. All DNA interactions, modifications and repairs constitute an amazing and highly efficiently functioning cellular system. Among the repair proteins there are some which affect the alkylated bases in a non-conventional way, very rarely occurring in nature. Especially amazing is the mechanism of action of dioxogenase AlkB, which combines the repair of methyl-, ethyl- and etheno-base derivatives with oxidation and dissociation of the modified groups, leading to direct recovery of natural bases. This review attempts to elucidate the role of the individual proteins involved in the repair processes.

UI	MeSH Term	Description	Entries
D008769	Methylnitronitrosoguanidine	A nitrosoguanidine derivative with potent mutagenic and carcinogenic properties.	Methylnitrosonitroguanidine,Nitrosomethylnitroguanidine,Nitrosonitromethylguanidine,MNNG,N-Methyl-N'-nitro-N-nitrosoguanidine,N Methyl N' nitro N nitrosoguanidine
D008770	Methylnitrosourea	A nitrosourea compound with alkylating, carcinogenic, and mutagenic properties.	Nitrosomethylurea,N-Methyl-N-nitrosourea,NSC-23909,N Methyl N nitrosourea,NSC 23909,NSC23909
D009153	Mutagens	Chemical agents that increase the rate of genetic mutation by interfering with the function of nucleic acids. A clastogen is a specific mutagen that causes breaks in chromosomes.	Clastogen,Clastogens,Genotoxin,Genotoxins,Mutagen
D004249	DNA Damage	Injuries to DNA that introduce deviations from its normal, intact structure and which may, if left unrepaired, result in a MUTATION or a block of DNA REPLICATION. These deviations may be caused by physical or chemical agents and occur by natural or unnatural, introduced circumstances. They include the introduction of illegitimate bases during replication or by deamination or other modification of bases; the loss of a base from the DNA backbone leaving an abasic site; single-strand breaks; double strand breaks; and intrastrand (PYRIMIDINE DIMERS) or interstrand crosslinking. Damage can often be repaired (DNA REPAIR). If the damage is extensive, it can induce APOPTOSIS.	DNA Injury,DNA Lesion,DNA Lesions,Genotoxic Stress,Stress, Genotoxic,Injury, DNA,DNA Injuries
D004260	DNA Repair	The removal of DNA LESIONS and/or restoration of intact DNA strands without BASE PAIR MISMATCHES, intrastrand or interstrand crosslinks, or discontinuities in the DNA sugar-phosphate backbones.	DNA Damage Response
D004269	DNA, Bacterial	Deoxyribonucleic acid that makes up the genetic material of bacteria.	Bacterial DNA
D004926	Escherichia coli	A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.	Alkalescens-Dispar Group,Bacillus coli,Bacterium coli,Bacterium coli commune,Diffusely Adherent Escherichia coli,E coli,EAggEC,Enteroaggregative Escherichia coli,Enterococcus coli,Diffusely Adherent E. coli,Enteroaggregative E. coli,Enteroinvasive E. coli,Enteroinvasive Escherichia coli
D006899	Mixed Function Oxygenases	Widely distributed enzymes that carry out oxidation-reduction reactions in which one atom of the oxygen molecule is incorporated into the organic substrate; the other oxygen atom is reduced and combined with hydrogen ions to form water. They are also known as monooxygenases or hydroxylases. These reactions require two substrates as reductants for each of the two oxygen atoms. There are different classes of monooxygenases depending on the type of hydrogen-providing cosubstrate (COENZYMES) required in the mixed-function oxidation.	Hydroxylase,Hydroxylases,Mixed Function Oxidase,Mixed Function Oxygenase,Monooxygenase,Monooxygenases,Mixed Function Oxidases,Function Oxidase, Mixed,Function Oxygenase, Mixed,Oxidase, Mixed Function,Oxidases, Mixed Function,Oxygenase, Mixed Function,Oxygenases, Mixed Function
D000477	Alkylating Agents	Highly reactive chemicals that introduce alkyl radicals into biologically active molecules and thereby prevent their proper functioning. Many are used as antineoplastic agents, but most are very toxic, with carcinogenic, mutagenic, teratogenic, and immunosuppressant actions. They have also been used as components in poison gases.	Alkylating Agent,Alkylator,Alkylators,Agent, Alkylating,Agents, Alkylating
D013014	SOS Response, Genetics	An error-prone mechanism or set of functions for repairing damaged microbial DNA. SOS functions (a concept reputedly derived from the SOS of the international distress signal) are involved in DNA repair and mutagenesis, in cell division inhibition, in recovery of normal physiological conditions after DNA repair, and possibly in cell death when DNA damage is extensive.	SOS Response (Genetics),SOS Box,SOS Function,SOS Induction,SOS Region,SOS Repair,SOS Response,SOS System,Box, SOS,Function, SOS,Functions, SOS,Genetics SOS Response,Genetics SOS Responses,Induction, SOS,Inductions, SOS,Region, SOS,Regions, SOS,Repair, SOS,Repairs, SOS,Response, Genetics SOS,Response, SOS,Response, SOS (Genetics),Responses, Genetics SOS,Responses, SOS,Responses, SOS (Genetics),SOS Functions,SOS Inductions,SOS Regions,SOS Repairs,SOS Responses,SOS Responses (Genetics),SOS Responses, Genetics,SOS Systems,System, SOS,Systems, SOS