Identification of the first eubacterial endonuclease coded by an intein allele in the pps1 gene of mycobacteria.
A survey of a vast range of mycobacterial strains led us to discover a new Pps1 intein allele in Mycobacterium gastri which differs from those of Mycobacterium tuberculosis and Mycobacterium leprae in both its sequence and insertion site. While little is known about Pps1, except that it belongs to the YC24 family of ABC transporters, we show that, unlike the other inteins described so far from Eubacteria, the MgaPps1 intein possesses a specific endonuclease activity. The intein is the first eubacterial intein to be characterised as an endonuclease. Like other intein endonucleases, its minimal sequence for recognition and cleavage is quite large, with 22 bp spanning the Pps1-c site. The fact that an active endonuclease is found among the mycobacterial inteins supports the concept of a cyclical model of invasion by horizontal transfer of these genes, followed by degeneration and loss until a new invasion event, thus explaining their long-term persistence in closely related eubacterial species.
Saves
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Institut de Pharmacologie et Biologie Structurale (UMR5089), CNRS/Université Paul Sabatier Toulouse III, 205 Route de Narbonne, F-31077 Toulouse Cedex, France. saves@ipbs.fr
Westrelin
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Daffé
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Masson
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D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D000483:Alleles; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D001483:Base Sequence; D002021:Buffers; D003001:Cloning, Molecular; D017124:Conserved Sequence; D004720:Endonucleases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D019143:Evolution, Molecular; D022761:Gene Transfer, Horizontal / Q000235:genetics; D005798:Genes, Bacterial / Q000235:genetics; D006863:Hydrogen-Ion Concentration; D008957:Models, Genetic; D008969:Molecular Sequence Data; D009161:Mycobacterium / Q000201:enzymology* / Q000235:genetics*; D011995:Recombination, Genetic / Q000235:genetics; D016415:Sequence Alignment; D013379:Substrate Specificity
D018528:ATP-Binding Cassette Transporters; D001426:Bacterial Proteins; D002021:Buffers; C439526:Pps1 protein, Mycobacterium gastri; C093709:pps1 protein, Mycobacterium sp.; D004720:Endonucleases