BMCB625:Helicases: Difference between revisions
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-- | Does the fact that helicase subunits are ''stabely'' bound by ADP in the crystal hint at something mechanistically important? | ||
The structure reveals several polar contacts between the helicase and DNA, but highly non-polar residues are within VDW distance of the DNA. However counter-intuitive, why might this be important? | |||
Revision as of 17:55, 23 May 2007
Bonus Materials
Review PCNA, the Maestro of the Replication Fork [[1]] A recent addition to Cell that looks at a critical component of the replication fork. --Chris 11:39, 18 May 2007 (EDT)
(Homework) Questions
Chris
Mahta
Q1. Separation of the duplex into ssDNA by the helicase via the proposed model utilizes one ATP for each base pair translocated through the center of the hexamer. Is this not an inefficient use of energy?
Q2. Is it clear whether the helicase hexamer is "pushing" the ssDNA through its center core or is the helicase itself translocating along the DNA strand? (See Fig S-5) The basis for this question lies in their claim that in vivo there are two hexamers - in one, all six subunits can bind DNA whereas in the second one only five of six subunits can bind DNA - does this favor "DNA pushing through" or the helicase translocating itself on the DNA?
Chayne
In Enemark & Joshua-Tor, they propose the "escort" model as opposed to the "bucket brigade". Since this is just conjecture based upon observations from structure (though a pretty good one), how could this model be more thoroughly tested?
some figures I made from pdb 2GXA (not really related to above question)
Media:Fig2-2GXA-loop-superpose.pdf
Media:Fig3-ADP_bs-lsqDE-ADPlike.png
Media:Fig4-ADP_bs-lsqABC-ATPlike.png
Media:Fig5-ADP_bs-lsqF-APOlike.png
Media:Fig7-ADP_bs-lsqall-view2.png
Jeremy
Does the fact that helicase subunits are stabely bound by ADP in the crystal hint at something mechanistically important?
The structure reveals several polar contacts between the helicase and DNA, but highly non-polar residues are within VDW distance of the DNA. However counter-intuitive, why might this be important?
