Question

Condensin I: where & when does this complex interact with DNA

Condensin II: where & when does this complex interact with DNA

-Miami University Research Question

Answer 1

ANSWER :-

1. DNA is called as Deoxyribose Nucleic Acid which usually codes for a genetic message to produce a particular enzyme or protein and this is located inside the chromosome.
2. During mitosis, the cell divides into two which is accompanied by proliferation or more specifically doubling of the DNA content and separation during the Anaphase Stage of mitosis.
3. Lets introduce two important terms namely catenation and decatenation. These basically stated the attachment and removal of attachment wlbetween the chromatids which are connected to centromere. These are being regulated by the enzyme Topoisomerase II although its initial role is to carry out separation of the DNA strands. But, the second activity is basically mediated by both the condensin molecules.
4. Condensin I is basically localized to the cytosol of the cell. It is in tight regulatory mechanism with the enzyme Topoisomerase II and enters the nucleus of the cell only when the condensation of the chromatid into the chromosome is mediated by the associated complex of Condensin II.
5. So, it should be clear that the complex II is strictly localized to the nucleus of the cell more specifically being part of the protein complex held by the DNA. It plays a vital role in the conversion of the chromatid content into chromosomes by mediating the condensation reaction. So, its activity is mainly focussed during the interphase to prophase transition event wherein maximum condensation happens and this complex II is thus carrying out the initial process that acts as a base for further process of separation. So, as the degree of condensation increases from chromatin fibres to chromosomes, maximal activity of Condensin II can be observed.
6. Condensin I is restricted into the cytosol of the cells until the condensation event has been completed and the cell has progressed through the prophase Stage. This is point for interaction of the complex with the DNA where it opposes the initial activity of topoisomerase II to bring out proper segregation of the DNA during Anaphase. Basically, if catenation or intertwining of the sister chromatid occurs during the initial stages, chances are that separation of the chromosomes during the Anaphase Stage would become difficult resulting into errors which can cause mutations. Although, complex I plays a vital role in reversing these mechanisms during initial stages by regulating activity of Topoisomerase II thereby leading to proper separation of chromosomes and proper alignment of the sister chromatid until cell division is completed.

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