PMID- 10205179
OWN - NLM
STAT- MEDLINE
DCOM- 19990611
LR  - 20220316
IS  - 0261-4189 (Print)
IS  - 1460-2075 (Electronic)
IS  - 0261-4189 (Linking)
VI  - 18
IP  - 8
DP  - 1999 Apr 15
TI  - Trypanosoma brucei variant surface glycoprotein regulation involves coupled 
      activation/inactivation and chromatin remodeling of expression sites.
PG  - 2265-72
AB  - Trypanosoma brucei is an extracellular protozoan parasite that cycles between 
      mammalian hosts and the tsetse vector. In bloodstream-form trypanosomes, only one 
      variant surface glycoprotein gene (VSG) expression site (ES) is active at any 
      time. Transcriptional switching between ESs results in antigenic variation. No 
      VSG is transcribed in the insect procyclic stage. We have used bacteriophage T7 
      RNA polymerase (T7RNAP) to study the transcriptional accessibility of ES 
      chromatin in vivo. We show that T7RNAP-mediated transcription from chromosomally 
      integrated T7 promoters is repressed along the entire length of the ES in the 
      procyclic form, but not in the bloodstream form, suggesting that the accessible 
      chromatin of inactive bloodstream-form ESs is remodeled upon differentiation to 
      yield a structure that is no longer permissive for T7RNAP-mediated transcription. 
      In the bloodstream form, replacing the active ES promoter with a T7 promoter, 
      which is incapable of sustaining high-level transcription of the entire ES, 
      prompts an ES switch. These data suggest two distinct mechanisms for ES 
      regulation: a chromatin-mediated developmental silencing of the ES in the 
      procyclic form and a rapid coupled mechanism for ES activation and inactivation 
      in the bloodstream form.
FAU - Navarro, M
AU  - Navarro M
AD  - Laboratory of Molecular Parasitology, The Rockefeller University (Box 185), 1230 
      York Avenue, New York, NY 10021-6399, USA.
FAU - Cross, G A
AU  - Cross GA
FAU - Wirtz, E
AU  - Wirtz E
LA  - eng
GR  - AI 21729/AI/NIAID NIH HHS/United States
PT  - Journal Article
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - England
TA  - EMBO J
JT  - The EMBO journal
JID - 8208664
RN  - 0 (Chromatin)
RN  - 0 (DNA Primers)
RN  - 0 (Variant Surface Glycoproteins, Trypanosoma)
RN  - 0 (Viral Proteins)
RN  - EC 2.7.7.- (bacteriophage T7 RNA polymerase)
RN  - EC 2.7.7.6 (DNA-Directed RNA Polymerases)
SB  - IM
MH  - Animals
MH  - Base Sequence
MH  - Chromatin/*metabolism
MH  - DNA Primers
MH  - DNA-Directed RNA Polymerases/genetics/metabolism
MH  - *Gene Expression Regulation
MH  - Promoter Regions, Genetic
MH  - *Transcription, Genetic
MH  - Trypanosoma brucei brucei/*metabolism
MH  - Variant Surface Glycoproteins, Trypanosoma/*genetics
MH  - Viral Proteins
PMC - PMC1171309
EDAT- 1999/04/16 00:00
MHDA- 1999/04/16 00:01
PMCR- 2000/04/15
CRDT- 1999/04/16 00:00
PHST- 1999/04/16 00:00 [pubmed]
PHST- 1999/04/16 00:01 [medline]
PHST- 1999/04/16 00:00 [entrez]
PHST- 2000/04/15 00:00 [pmc-release]
AID - 10.1093/emboj/18.8.2265 [doi]
PST - ppublish
SO  - EMBO J. 1999 Apr 15;18(8):2265-72. doi: 10.1093/emboj/18.8.2265.