Biomaterial Database

Endonuclease (R) subunits of type-I and type-III restriction-modification enzymes contain a helicase-like domain. 1991

A E Gorbalenya, and E V Koonin

Institute of Poliomyelitis and Viral Encephalitides, USSR Academy of Medical Sciences, Moscow Region.

A statistically significant amino acid sequence similarity is demonstrated between the endonuclease (R) subunit of EcoK restriction-modification (R-M) enzyme, and RNA and DNA helicases of the so-called 'DEAD' family. It is further shown that all three known sequences of R subunits of type-I and type-III R-M enzymes contain the conserved amino acid sequence motifs typical of the previously described helicase superfamily II [(1989) Nucleic Acids Res. 17, 4713-4730]. A hypothesis is proposed that these enzymes may exert helicase activity possibly required for local unwinding of DNA in the cleavage sites.

UI	MeSH Term	Description	Entries
D008969	Molecular Sequence Data	Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.	Sequence Data, Molecular,Molecular Sequencing Data,Data, Molecular Sequence,Data, Molecular Sequencing,Sequencing Data, Molecular
D004247	DNA	A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine).	DNA, Double-Stranded,Deoxyribonucleic Acid,ds-DNA,DNA, Double Stranded,Double-Stranded DNA,ds DNA
D004265	DNA Helicases	Proteins that catalyze the unwinding of duplex DNA during replication by binding cooperatively to single-stranded regions of DNA or to short regions of duplex DNA that are undergoing transient opening. In addition, DNA helicases are DNA-dependent ATPases that harness the free energy of ATP hydrolysis to translocate DNA strands.	ATP-Dependent DNA Helicase,DNA Helicase,DNA Unwinding Protein,DNA Unwinding Proteins,ATP-Dependent DNA Helicases,DNA Helicase A,DNA Helicase E,DNA Helicase II,DNA Helicase III,ATP Dependent DNA Helicase,ATP Dependent DNA Helicases,DNA Helicase, ATP-Dependent,DNA Helicases, ATP-Dependent,Helicase, ATP-Dependent DNA,Helicase, DNA,Helicases, ATP-Dependent DNA,Helicases, DNA,Protein, DNA Unwinding,Unwinding Protein, DNA,Unwinding Proteins, DNA
D004720	Endonucleases	Enzymes that catalyze the hydrolysis of the internal bonds and thereby the formation of polynucleotides or oligonucleotides from ribo- or deoxyribonucleotide chains. EC 3.1.-.	Endonuclease
D005810	Multigene Family	A set of genes descended by duplication and variation from some ancestral gene. Such genes may be clustered together on the same chromosome or dispersed on different chromosomes. Examples of multigene families include those that encode the hemoglobins, immunoglobulins, histocompatibility antigens, actins, tubulins, keratins, collagens, heat shock proteins, salivary glue proteins, chorion proteins, cuticle proteins, yolk proteins, and phaseolins, as well as histones, ribosomal RNA, and transfer RNA genes. The latter three are examples of reiterated genes, where hundreds of identical genes are present in a tandem array. (King & Stanfield, A Dictionary of Genetics, 4th ed)	Gene Clusters,Genes, Reiterated,Cluster, Gene,Clusters, Gene,Families, Multigene,Family, Multigene,Gene Cluster,Gene, Reiterated,Multigene Families,Reiterated Gene,Reiterated Genes
D000595	Amino Acid Sequence	The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.	Protein Structure, Primary,Amino Acid Sequences,Sequence, Amino Acid,Sequences, Amino Acid,Primary Protein Structure,Primary Protein Structures,Protein Structures, Primary,Structure, Primary Protein,Structures, Primary Protein
D012316	RNA Nucleotidyltransferases	Enzymes that catalyze the template-directed incorporation of ribonucleotides into an RNA chain. EC 2.7.7.-.	Nucleotidyltransferases, RNA
D013329	Structure-Activity Relationship	The relationship between the chemical structure of a compound and its biological or pharmacological activity. Compounds are often classed together because they have structural characteristics in common including shape, size, stereochemical arrangement, and distribution of functional groups.	Relationship, Structure-Activity,Relationships, Structure-Activity,Structure Activity Relationship,Structure-Activity Relationships
D015253	Deoxyribonucleases, Type I Site-Specific	Enzyme systems containing three different subunits and requiring ATP, S-adenosylmethionine, and magnesium for endonucleolytic activity to give random double-stranded fragments with terminal 5'-phosphates. They function also as DNA-dependent ATPases and modification methylases, catalyzing the reactions of EC 2.1.1.72 and EC 2.1.1.73 with similar site-specificity. The systems recognize specific short DNA sequences and cleave at sites remote from the recognition sequence. Enzymes from different microorganisms with the same specificity are called isoschizomers. EC 3.1.21.3.	DNA Restriction Enzymes, Type I,DNase, Site-Specific, Type I,Restriction Endonucleases, Type I,Type I Restriction Enzymes,DNase, Site Specific, Type I,Deoxyribonucleases, Type I, Site Specific,Deoxyribonucleases, Type I, Site-Specific,Site-Specific DNase, Type I,Type I Site Specific DNase,Type I Site Specific Deoxyribonucleases,Type I Site-Specific DNase,Type I Site-Specific Deoxyribonucleases,Deoxyribonucleases, Type I Site Specific,Site Specific DNase, Type I
D015263	Deoxyribonucleases, Type III Site-Specific	Enzyme systems composed of two subunits and requiring ATP and magnesium for endonucleolytic activity; they do not function as ATPases. They exist as complexes with modification methylases of similar specificity listed under EC 2.1.1.72 or EC 2.1.1.73. The systems recognize specific short DNA sequences and cleave a short distance, about 24 to 27 bases, away from the recognition sequence to give specific double-stranded fragments with terminal 5'-phosphates. Enzymes from different microorganisms with the same specificity are called isoschizomers. EC 3.1.21.5.	DNA Restriction Enzymes, Type III,DNase, Site-Specific, Type III,Restriction Endonucleases, Type III,Type III Restriction Enzymes,DNase, Site Specific, Type III,Deoxyribonucleases, Type III, Site Specific,Deoxyribonucleases, Type III, Site-Specific,Site-Specific DNase, Type III,Type III Site Specific DNase,Type III Site Specific Deoxyribonucleases,Type III Site-Specific DNase,Type III Site-Specific Deoxyribonucleases,Deoxyribonucleases, Type III Site Specific,Site Specific DNase, Type III