|
|
|
|
|
|
Vibrio cholerae Biofilms: Stuck between a Rock and a Hard Place. Douglas M. Heithoff, 2004. Tn5 Transposase with an Altered Specificity for Transposon Ends. Todd A. Naumann, 2002.Tn5 is a composite bacterial transposon that encodes a protein, transposase (Tnp), required for movement of the transposon . The initial step in the transposition pathway involves specific binding of Tnp to 19-bp end recognition sequences . Tn5 contains two different specific end sequences, termed outside end (OE) and inside end (IE) . In Escherichia coli, IE is methylated by Dam methylase (IEME) . This methylation greatly inhibits recognition by Tnp and greatly reduces the ability of transposase to facilitate movement of IE defined transposons . Through use of a combinatorial random mutagenesis technique (DNA shuffling), we have isolated an IEME-specific hyperactive form of Tnp, Tnp sC7v.2.0, that is able to promote high levels of transposition of IEME defined transposons in vivo and in vitro while functioning at wild-type levels with OE transposons . This protein contains a critical glutamate-to-valine mutation at amino acid 58 that is responsible for this change in end specificity . Roles of YqjH and YqjW, Homologs of the Escherichia coli UmuC/DinB or Y Superfamily of DNA Polymerases, in Stationary-Phase Mutagenesis and UV-Induced Mutagenesis of Bacillus subtilis. Huang-Mo Sung, 2003.YqjH and YqjW are Bacillus subtilis homologs of the UmuC/DinB or Y superfamily of DNA polymerases that are involved in SOS-induced mutagenesis in Escherichia coli . While the functions of YqjH and YqjW in B . subtilis are still unclear, the comparisons of protein structures demonstrate that YqjH has 36% identity to E . coli DNA polymerase IV (DinB protein), and YqjW has 26% identity to E . coli DNA polymerase V (UmuC protein) . In this report, we demonstrate that both YqjH and the products of the yqjW operon are involved in UV-induced mutagenesis in this bacterium . Furthermore, resistance to UV-induced damage is significantly reduced in cells lacking a functional YqjH protein . Analysis of stationary-phase mutagenesis indicates that absences of YqjH, but not that of YqjW, decreases the ability of B . subtilis to generate revertants at the hisC952 allele via this system . These data suggest a role for YqjH in the generation of at least some types of stationary-phase-induced mutagenesis .
|
© 2005
Transgalactic Ltd (manufacturer of Bioscreen C software) |
Privacy Statement | P.O. Box
1393, 00101 Helsinki, Finland,
Last modified: May 25, 2005
| ||||||
