|
|
|
|
|
|
|
||
J. Exp. Med.,
Volume 188, Number 4, August 17, 1998 689-698
By
From the * Department of Molecular Genetics and Cell Biology and the Immunoglobulin (Ig) genes expressed in mature B lymphocytes can undergo somatic hypermutation upon cell interaction with antigen and T cells. The mutation mechanism had previously been shown to depend upon transcription initiation, suggesting that a mutator factor was
loaded on an RNA polymerase initiating at the promoter and causing mutations during elongation (Peters, A., and U. Storb. 1996. Immunity. 4:57-65). To further elucidate this process we have created an artificial substrate consisting of alternating EcoRV and PvuII restriction enzyme sites (EPS) located within the variable (V) region of an Ig transgene. This substrate can easily be assayed for the presence of mutations in DNA from transgenic lymphocytes by amplifying the EPS insert and determining by restriction enzyme digestion whether any of the restriction sites have been altered. Surprisingly, the EPS insert was mutated many times more frequently than the flanking Ig sequences. In addition there were striking differences in mutability
of the different nucleotides within the restriction sites. The data favor a model of somatic hypermutation where the fine specificity of the mutations is determined by nucleotide sequence
preferences of a mutator factor, and where the general site of mutagenesis is determined by the
pausing of the RNA polymerase due to secondary structures within the nascent RNA.
Committee on Immunology,
University of Chicago, Chicago, Illinois 60637
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
This article has been cited by other articles:
| TABLE OF CONTENTS |
|
