DNA uptake sequences are widespread throughout the Neisseria gonorrhoeae genome. These short, conserved sequences facilitate the exchange of endogenous DNA between members of the genus Neisseria. Often the DNA uptake sequences are present as inverted repeats that are able to form hairpin structures. It has been suggested previously that DNA uptake sequence inverted repeats present 3' of genes p...

Naturally TALEs are pathogenicity factors secreted by Xanthomonas spp. into host plant cells to bind specific promoters and manipulate host transcription. Sequence specific DNA binding is conferred by the TALE repeat array. Natural TALE repeat arrays are formed of 10-30 repeats, each of which pairs with one DNA base. Collectively the repeats of a TALE array form a righthanded superhelix, enfold...

By screening a library of unintegrated, circular Moloney murine leukemia virus (M-MuLV) DNA cloned in lambda phage, we found that approximately 20% of the M-MuLV DNA inserts contained internal sequence deletions or inversions. Restriction enzyme mapping demonstrated tht the deleted segments frequently abutted a long terminal repeat (LTR) sequence, whereas the inverted segments were usually flan...

DNA repeat domains can form ensembles of canonical and noncanonical states, including stable and metastable DNA secondary structures. Such sequence-induced structural diversity creates complex conformational landscapes for DNA processing pathways, including those triplet expansion events that accompany replication, recombination, and/or repair. Here we demonstrate further levels of conformation...

Most models proposed to explain the disease-associated expansion of (CTG)n.(CAG)n and (CGG)n.(CCG)n trinucleotide repeats include the formation of slipped strand DNA structures during replication; however, physical evidence for these alternative DNA secondary structures has not been reported. Using cloned fragments from the myotonic dystrophy (DM) and fragile X syndrome (FRAXA) loci containing ...

The human genome contains many simple tandem repeats that are widely dispersed and highly polymorphic. At least one group of simple tandem repeats, the DNA trinucleotide repeats, can dramaticallyexpand in size during transmission from one generation to the next to cause disease by a process known as dynamic mutation. We investigated the ability of trinucleotide repeats AAT and CAG to expand in ...

The expansion of trinucleotide repeat sequences is associated with several neurodegenerative diseases. The mechanism of this expansion is unknown but may involve slipped-strand structures where adjacent rather than perfect complementary sequences of a trinucleotide repeat become paired. Here, we have studied the interaction of the human mismatch repair protein MSH2 with slipped-strand structure...

All DNA repeats known to undergo expansion leading to human neurodegenerative disease can form one, or several, alternative conformations, including hairpin, slipped strand, triplex, quadruplex, or unwound DNA structures. These alternative structures may interfere with the normal cellular processes of transcription, DNA repair, replication initiation, or polymerase elongation and thereby contri...