Search results
Results From The WOW.Com Content Network
DNA gyrase, or simply gyrase, is an enzyme within the class of topoisomerase and is a subclass of Type II topoisomerases [1] that reduces topological strain in an ATP dependent manner while double-stranded DNA is being unwound by elongating RNA-polymerase [2] or by helicase in front of the progressing replication fork.
HU is a small (10 kDa [12]) bacterial DNA-binding protein, which structurally differs from a eukaryotic histone but functionally acts similarly to a histone by inducing negative supercoiling into circular DNA with the assistance of topoisomerase. The protein has been implicated in DNA replication, recombination, and repair.
[25] [26] It catalyses the relaxation of negatively or positively superhelical DNA and is employed in phage DNA replication during infection of the E. coli bacterial host. [27] The phage gene 52 protein shares homology with the E. coli gyrase gyrA subunit [28] and the phage gene 39 protein shares homology with the gyr B subunit. [29]
Negative supercoils favor local unwinding of the DNA, allowing processes such as transcription, DNA replication, and recombination. Negative supercoiling is also thought to favour the transition between B-DNA and Z-DNA , and moderate the interactions of DNA binding proteins involved in gene regulation .
With DNA in its "relaxed" state, a strand usually circles the axis of the double helix once every 10.4 base pairs, but if the DNA is twisted the strands become more tightly or more loosely wound. [43] If the DNA is twisted in the direction of the helix, this is positive supercoiling, and the bases are held more tightly together.
Helix-turn-helix is a DNA-binding domain (DBD). The helix-turn-helix (HTH) is a major structural motif capable of binding DNA. Each monomer incorporates two α helices, joined by a short strand of amino acids, that bind to the major groove of DNA. The HTH motif occurs in many proteins that regulate gene expression
This DNA loop formation allows H-NS to control gene expression. [2] Relief of suppression by H-NS can be achieved by the binding of another protein, or by changes in DNA topology which can occur due to changes in temperature and osmolarity, for example. [6] The CTD binds to the bacterial DNA in such a way that inhibits the function of RNA ...
The surface of bacteria such as E. coli is negatively charged due to phospholipids and lipopolysaccharides on its cell surface, and the DNA is also negatively charged. One function of the divalent cation therefore would be to shield the charges by coordinating the phosphate groups and other negative charges, thereby allowing a DNA molecule to ...