In order to study the functional structure of thetranscription terminators and the mechanism oftermination,a survey of the chromatin structure,including the location of DNase I hypersensitive sitesand the nucleosome arrangement,of yeast ADH1 andFLP terminators was made.The results show that thereis no relationship between the function of theterminators and the existence of DNase I hypersensitivesites.However,it is found that there is always anucleosome at the immediate upstream of the transcrip-tional termination sites.As a control,the chromatinstructures of the pBR322 DNA fragments on the yeastshutter vectors are also investigated at the same time.The random nucleosome arrangement on the bacterialDNA in yeast agrees with the published reports.A newhypothesis,about the mechanism of transcriptionaltermination is put forward and the reason of differentnucleosome arrangement on the DNAs which areori-ginally from different species in yeast is discussed.
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