Inhibition of bacteriophage Mu transposition by Mu repressor and Fis.
In this paper we show that the Escherichia coli protein Fis has a regulatory function in Mu transposition in the presence of Mu repressor. Fis can lower the transposition frequency of a mini-Mu 3-80-fold, but only if the Mu repressor is expressed simultaneously. In this novel type of regulation of transposition by the concerted action of Fis and repressor, the IAS, the internal activating sequence, is also involved as deletion of this site lead to the loss of the Fis effect. As the IAS contains strong repressor binding sites these are probably the target for the repressor in the observed negative regulation by Fis and repressor. However, the role of Fis and repressor is not only to inactivate the IAS, since a 4 bp insertion in the IAS, which changes the spacing of the repressor-binding site, abolishes the enhancing function of the IAS but leaves the repressor-Fis effect intact. A likely target for Fis in this regulation is a strong Fis-binding site, which is located adjacent to the L2 transposase-binding site. However, when this Fis-binding sequence was substituted by a random sequence and Fis no longer showed specific binding to this site, the Fis effect was still observed. Although it is still possible that Fis can function by binding to this non-specific site in a particular complex, it seems more likely that Fis is directly or indirectly involved in determining the level of the repressor.
van Drunen
C M
CM
Department of Biochemistry, Gorlaeus Laboratoria, Leiden University, The Netherlands.
van Zuylen
C
C
Mientjes
E J
EJ
Goosen
N
N
van de Putte
P
P
D010583:Bacteriophage mu / Q000235:genetics*; D001483:Base Sequence; D002352:Carrier Proteins / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism; D004926:Escherichia coli / Q000821:virology*; D029968:Escherichia coli Proteins; D035021:Factor For Inversion Stimulation Protein; D034982:Integration Host Factors; D008969:Molecular Sequence Data; D009713:Nucleotidyltransferases / Q000378:metabolism; D011485:Protein Binding; D011995:Recombination, Genetic / Q000235:genetics*; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics; D012097:Repressor Proteins / Q000378:metabolism*; D019895:Transposases; D014764:Viral Proteins / Q000378:metabolism*; D054334:Viral Regulatory and Accessory Proteins
D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D035021:Factor For Inversion Stimulation Protein; D034982:Integration Host Factors; C050938:Mu B protein, bacteriophage; D012097:Repressor Proteins; D014764:Viral Proteins; D054334:Viral Regulatory and Accessory Proteins; C440502:integration host factor, E coli; C016649:phage repressor proteins; D009713:Nucleotidyltransferases; D019895:Transposases