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Organization,
function and phylogeny of the DNA
mismatch
repair system in bacteria
Abstract:
The postreplication mismatch repair system (MMR) is
evolutionarily conserved and stabilizes the cellular genome by
correcting DNA
replication
errors. The methyl-directed Mut HSL pathway is able to
recognize and repair all base-base mismatches (except C/C) and
small insertion/deletion mismatches that arise during DNA
replication.
The MMR enzymes protect the cell against mutations as well as
interspecies recombination, whereas the SOS response increases
both. There is the wide range of effects that MMR can exert;
the
VSP (Very Short Pathway) and TCR (Transcription - Coupled
Nucleotide-Excision Repair) systems of Escherichia coli
are strongly stimulated or supported by the MMR factors MutS and
MutL but not by MutH. MMR factors are required for the repair of mismatches
in heteroduplex DNA
that
form as a result of interspecies recombination between divergent DNA
sequences.
In addition, MutH, S,
L proteins
play an important role in rearrangement of chromosomal DNA
subsequent
to strand-slippage mutagenesis of tandemly repeated sequences,
and can act to prevent interchromosomal exchanges between
homologous DNAs. The multiple homologues of bacterial MutS and
MutL exist in eukaryotes but play different roles in the MMR
pathway or in recombination.
1. Introduction.
2. General
organization and function of MMR system. 3. Characteristics
of genes and repair proteins of MMR. 4. Contribution
of MMR to the other molecular processes in the cell. 5. MMR
system in the light of bacterial genomics achievements |
