Which of the following features of the structure of double-stranded DNA is most
ID: 573441 • Letter: W
Question
Which of the following features of the structure of double-stranded DNA is most important in recognition of specific base sequences by most sequence–specific DNA-binding proteins?
The tilt of base pairs in the minor groove.
The arrangement of sequence-specific functional groups in the major groove.
The arrangement of sequence-specific functional groups in the minor groove.
The tilt of base pairs in the major groove.
The greater depth of the minor groove.
Which of the following features of the structure of double-stranded DNA is most important in recognition of specific base sequences by most sequence–specific DNA-binding proteins?
The tilt of base pairs in the minor groove.
The arrangement of sequence-specific functional groups in the major groove.
The arrangement of sequence-specific functional groups in the minor groove.
The tilt of base pairs in the major groove.
The greater depth of the minor groove.
Explanation / Answer
Ans. Correct option- C. The arrangement of sequence-specific functional groups in the major groove.
# Most of DNA binding proteins require following two features of DNA –
1. All DNA-binding proteins (DBP) bind DNA only to specific base sequence. The interaction is between the functional groups on the active site amino acids of DBP and the functional groups on the specific sequences on the specified region of DNA.
2. Most DBP bind DNA at specified major groove.
Only a few DBP bind to the minor grove.
So, option C is the most suitable one.
# Option A, D – Incorrect. All constituent bases exhibit almost the same tilt to the vertical axis. That is, discrimination of a region solely on the basis of “base tilt” is impossible.
The DBP only binds to specific base sequences.
# Option C – Incorrect. Most of DBP bind to specific sequences in the major groove because this the functional groups of bases are simultaneously exposed better in the major groove compared to those in the minor groove.
# Option E. see #C.
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