Functional analysis of Meq, a Marek's disease virus (MDV)bZIP protein associated with T cell transformation

 
 
 
 

Functional analysis of Meq, a Marek's disease virus (MDV)bZIP protein associated with T cell transformation

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Title: Functional analysis of Meq, a Marek's disease virus (MDV)bZIP protein associated with T cell transformation
Author: Qian, Zheng
Description: Marek's disease virus (MDV) causes malignant T cell lymphoma in chickens and is the major pathogen in poultry industry. The viral gene meq is abundantly expressed in MDV-transformed cell lines and MDV tumor samples. It contains a basic leucine-zipper region highly homologous to those of jun and fos, and a C-terminal proline-rich region including two and one-half repeat sequence (PRRs). In this report, we demonstrate that the proline-rich domain in the C-terminus of Meq is able to transactivate transcription when fused to the Ga14 DNA-binding domain, with the last 33 amino acids being essential for this activity. Full activity also requires at least one PRR, although fusion of itself alone with the DNA-binding domain represses transcription. Meq is able to dimerize with C-Jun and activate meq transcription through an AP-1-like motif in the meq promoter. The optimal binding sites of Meq/C-Jun and Meq/Meq are determined. Meq/C-Jun heterodimers bind a consensus with a core TRE/CRE site PuPuTGAC(G)TCAT. Meq homodimers bind two groups of DNA sequences. Group I site has a consensus GAGTGATGAC(G)TCATC, group II PuACACACAPy. By methylation interference assays and mutagenesis analysis, crucial nucleotides for the binding are identified. By computer simulation and circular pe rmutation assays, we further suggest that group II binding sites are intrinsically bent, and the DNA bending is necessary for the recognition by Meq/Meq. These results provide crucial information in the search of the functional targets of Meq, and shed new light on the general mechanism of DNA recognition by bZIP proteins
Permanent Link: http://rave.ohiolink.edu/etdc/view?acc_num=case1057671034
http://hdl.handle.net/2374.OX/17117
Date: 1996

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