Cloning and characterization of the genes of the CeqI restriction—modification system

Two genes from Corynebacterium equii, a Gram-positive bacterium producing the CeqI restriction—modification enzymes were cloned and sequenced. In vivo restriction experiments, DNA and amino acid sequence data suggest that the two genes code for the endonuclease and the methyltransferase enzymes. How...

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Bibliographic Details
Published in:The international journal of biochemistry & cell biology 1997-06, Vol.29 (6), p.895-900
Main Authors: Izsvák, Zsuzsa, Jobbágy, Zsolt, Takács, Imre, Duda, Ernő
Format: Article
Language:English
Subjects:
Amino Acid Sequence
Base Sequence
Cloning, Molecular
Corynebacterium - enzymology
Corynebacterium - genetics
Corynebacterium equii
Deoxyribonucleases, Type II Site-Specific - genetics
DNA methylation
EcoRV izoschizomer
Genes, Bacterial
Genetic Code
Hydrophobicity
Molecular Sequence Data
Primary sequence
Recombinant DNA
Sequence Homology, Amino Acid
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Summary:Two genes from Corynebacterium equii, a Gram-positive bacterium producing the CeqI restriction—modification enzymes were cloned and sequenced. In vivo restriction experiments, DNA and amino acid sequence data suggest that the two genes code for the endonuclease and the methyltransferase enzymes. However, when the two genes are expressed in E. coli, practically no enzyme activity can be detected in the supernatants of sonicated cells. Based on the DNA sequence data CeqI restriction endonuclease (an EcoRV izoschizomer) consists of 270 amino acid residues with a predicted molecular mass of 31.6 kDa, in good agreement with the previously measured 32 ± 2 kDa. The methyltransferase is 517 residues long (approx. 60 kDa). The two genes are in opposite orientation and overlap by 37 base pairs on the chromosome. The deduced amino acid sequence of the putative endonuclease gene revealed long stretches of hydrophobic amino acids, that may form the structural basis of the unusual aggregation properties of the restriction endonuclease. The amino acid sequence of the methylase shows homologies with other type II methyltransferases.
ISSN:1357-2725
1878-5875
DOI:10.1016/S1357-2725(97)00029-0