From owner-biophysics@net.bio.net Thu Dec 17 22:00:00 1998 From: "clive delmonte" Newsgroups: bionet.biophysics References: <3674c735.0@news.netdirect.net.uk> <3676A5B5.FDDF8CB@york.ac.uk> Subject: Re: DNA Structure: Puzzle Number 11 (Discussion) Date: Fri, 18 Dec 1998 15:42:52 -0000 X-Newsreader: Microsoft Outlook Express 4.71.1712.3 X-MimeOLE: Produced By Microsoft MimeOLE V4.71.1712.3 NNTP-Posting-Host: 195.7.227.189 Message-ID: <367a720f.0@news.netdirect.net.uk> X-Trace: 18 Dec 1998 15:17:35 GMT, 195.7.227.189 Path: biosci!agate!newsfeed.berkeley.edu!woodstock.news.demon.net!demon!dispose.news.demon.net!demon!news.netkonect.net!peer.news.nildram.co.uk!news-peer.netdirect.net.uk!news.netdirect.net.uk!195.7.227.189 Lines: 43 Dr Knight's comments are an interesting reflection of how it is possible to draw quite different conclusions from the same scientific report. Kabata et al. found direct evidence of RNA polymerase sliding along tethered duplex DNA. These authors did not mention rotation (as Dr Knight says) but I take this to be because there was none. When I corresponded with Dr Kabata about the reading of alternating half turns by the polymerase, his reply to me made it clear that he was thinking in terms of RNA polymerase working while sliding and he supposed that the polymerase would need two reading frames to cope with the alternating half turns. If Dr Knight means to imply that sliding might take place without the polymerase carrying out, or being able to carry out its normal functions, which is certainly a possibility, then this seems to me to warrant a new program of experiments to determine whether the sliding can take place simultaneously with the normal functioning of the RNA polymerase, or not. The fact remains that sliding takes place and seems to warrant further work since the side-by-side model of Lee et al. (Puzzle 1, ref. 1) only requires sliding and does not require a helical rotation of the polymerase. Clive Delmonte ----------------------------------------------------------- Alex Knight wrote in message <3676A5B5.FDDF8CB@york.ac.uk>... >This is an interesting statement, but as far as I can recall this paper showed >no such thing. Two points: >- I may be wrong, but the paper made no claims about measuring rotation. This >would be quite difficult to do... >- In any case, the sliding behaviour observed is quite distinct from >transcription! > >Alex > >Alex Knight (aek4@york.ac.uk) >Biology Department, University of York >http://motility.york.ac.uk:85/ >http://www.york.ac.uk/depts/biol/units/coils/coilcoil.html > > .