同聚環(huán)ATP酶見于所有生命形式中,，參與很多過程,，如染色體分離、蛋白解折疊和ATP合成,。這種引人注目的功能多樣性是由一個(gè)高度保留的結(jié)構(gòu)核產(chǎn)生的,，該結(jié)構(gòu)核負(fù)責(zé)ATP的結(jié)合和水解。但這些酶是怎樣協(xié)調(diào)ATP水解及機(jī)制功能的卻基本不清楚,。其中一種這樣的環(huán)ATP酶來自一種名為phi29的噬菌體,，它幫助將dsDNA基因組加載到病毒殼中。
在最新一期Nature上面,，Moffitt等人發(fā)現(xiàn),，這一由5部分組成的運(yùn)動(dòng)機(jī)制將DNA包裝在由10個(gè)堿基對(duì)組成的“爆發(fā)”中，每個(gè)“爆發(fā)”由4個(gè)包含2.5個(gè)堿基對(duì)的步驟組成,，每個(gè)步驟相應(yīng)于每個(gè)ATP的水解,。這樣一個(gè)非整步的大小是前所未有的,，它提出了關(guān)于環(huán)內(nèi)ATP水解及ATP環(huán)與DNA相互作用的有趣的機(jī)制問題。（生物谷Bioon.com）
生物谷推薦原始出處：
Nature 457, 446-450 (22 January 2009) | doi:10.1038/nature07637
Intersubunit coordination in a homomeric ring ATPase
Jeffrey R. Moffitt1,6, Yann R. Chemla1,6,7, K. Aathavan2, Shelley Grimes3, Paul J. Jardine3, Dwight L. Anderson3,4 & Carlos Bustamante1,2,5
1 Department of Physics and Jason L. Choy Laboratory of Single Molecule Biophysics,
2 Biophysics Graduate Group, University of California, Berkeley, California 94720, USA
3 Department of Diagnostic and Biological Sciences,
4 Department of Microbiology, University of Minnesota, Minneapolis, Minnesota 55455, USA
5 Departments of Molecular and Cell Biology, Chemistry, and Howard Hughes Medical Institute, University of California, Berkeley, California 94720, USA
6 These authors contributed equally to this work.
Homomeric ring ATPases perform many vital and varied tasks in the cell, ranging from chromosome segregation to protein degradation. Here we report the direct observation of the intersubunit coordination and step size of such a ring ATPase, the double-stranded-DNA packaging motor in the bacteriophage 29. Using high-resolution optical tweezers, we find that packaging occurs in increments of 10 base pairs (bp). Statistical analysis of the preceding dwell times reveals that multiple ATPs bind during each dwell, and application of high force reveals that these 10-bp increments are composed of four 2.5-bp steps. These results indicate that the hydrolysis cycles of the individual subunits are highly coordinated by means of a mechanism novel for ring ATPases. Furthermore, a step size that is a non-integer number of base pairs demands new models for motor–DNA interactions.
