PMID- 16105831
OWN - NLM
STAT- MEDLINE
DCOM- 20051213
LR  - 20210209
IS  - 0021-9258 (Print)
IS  - 0021-9258 (Linking)
VI  - 280
IP  - 42
DP  - 2005 Oct 21
TI  - The translational efficiencies of the two Leishmania infantum HSP70 mRNAs, 
      differing in their 3'-untranslated regions, are affected by shifts in the 
      temperature of growth through different mechanisms.
PG  - 35172-83
AB  - Exposure of Leishmania promastigotes to the temperature of their mammalian hosts 
      induces a typical heat-shock response. In Leishmania infantum, HSP70 is encoded 
      by two types of genes that differ in their 3'-untranslated regions (3'-UTRs). 
      Previously, we have shown that specific transcripts for each gene are present in 
      promastigotes growing at normal temperature (26 degrees C), but only transcripts 
      with 3'-UTR-type I (3'-UTRI) accumulate in a temperature-dependent manner. Here, 
      we have investigated the translational efficiencies of both types of HSP70 
      transcripts at the different temperatures that the parasite encounters in the 
      insect (26 degrees C, normal temperature) or in the mammalian host (heat-shock 
      temperatures). Interestingly, 3'-UTRI-bearing transcripts (HSP70-I) were found 
      associated with ribosomes in promastigotes at normal and heat-shock temperatures, 
      whereas the HSP70-II transcripts appear to be preferentially translated at 
      heat-shock temperatures but not at 26 degrees C. We have analyzed the function of 
      these UTRs in the translational control by use of plasmid constructs in which the 
      CAT reporter gene was flanked by UTRs of the HSP70 genes. Unexpectedly, it was 
      found that CAT transcripts with 3'-UTRII bind to ribosomes at 26 degrees C, and, 
      indeed, the CAT protein is synthesized. A valid conclusion of these experiments 
      was that both types of 3'-UTRs are essential for translation of HSP70 mRNAs at 
      heat shock temperatures, although the 3'-UTRII is more efficient during severe 
      heat shock (39 degrees C). In addition, these results suggest that sequence 
      region other than the 3'-UTR of HSP70-II gene is involved in the translational 
      silent state of HSP70-II transcripts at 26 degrees C. Finally, a null mutant has 
      been created by targeted disruption of both HSP70-II alleles. Remarkably, the 
      deltaHSP70 mutant synthesizes HSP70 at a lower rate than the wild-type parasites. 
      Overall, our data suggest that the biological function of the HSP70-II gene is to 
      top up HSP70 levels under conditions of stress.
FAU - Folgueira, Cristina
AU  - Folgueira C
AD  - Centro de Biologia Molecular Severo Ochoa, Universidad Autonoma de Madrid, 28049 
      Madrid, Spain.
FAU - Quijada, Luis
AU  - Quijada L
FAU - Soto, Manuel
AU  - Soto M
FAU - Abanades, Daniel R
AU  - Abanades DR
FAU - Alonso, Carlos
AU  - Alonso C
FAU - Requena, Jose M
AU  - Requena JM
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20050815
PL  - United States
TA  - J Biol Chem
JT  - The Journal of biological chemistry
JID - 2985121R
RN  - 0 (3' Untranslated Regions)
RN  - 0 (HSP70 Heat-Shock Proteins)
RN  - 0 (Heat-Shock Proteins)
RN  - 0 (RNA, Messenger)
RN  - 57-50-1 (Sucrose)
RN  - 63231-63-0 (RNA)
RN  - 9007-49-2 (DNA)
SB  - IM
MH  - *3' Untranslated Regions
MH  - Alleles
MH  - Animals
MH  - Blotting, Northern
MH  - Blotting, Southern
MH  - Blotting, Western
MH  - Chromosome Mapping
MH  - DNA/chemistry
MH  - Electrophoresis, Polyacrylamide Gel
MH  - Gene Deletion
MH  - Genes, Reporter
MH  - HSP70 Heat-Shock Proteins/*genetics/metabolism/*physiology
MH  - Heat-Shock Proteins/metabolism
MH  - Hot Temperature
MH  - Immunoprecipitation
MH  - Insecta
MH  - Leishmania infantum/*metabolism
MH  - Models, Genetic
MH  - Mutation
MH  - Phenotype
MH  - Plasmids/metabolism
MH  - Polyribosomes/chemistry/metabolism
MH  - *Protein Biosynthesis
MH  - RNA/chemistry
MH  - RNA Processing, Post-Transcriptional
MH  - RNA, Messenger/*metabolism
MH  - Subcellular Fractions/metabolism
MH  - Sucrose/pharmacology
MH  - Temperature
MH  - Time Factors
MH  - Transfection
EDAT- 2005/08/18 09:00
MHDA- 2005/12/15 09:00
CRDT- 2005/08/18 09:00
PHST- 2005/08/18 09:00 [pubmed]
PHST- 2005/12/15 09:00 [medline]
PHST- 2005/08/18 09:00 [entrez]
AID - S0021-9258(19)48188-X [pii]
AID - 10.1074/jbc.M505559200 [doi]
PST - ppublish
SO  - J Biol Chem. 2005 Oct 21;280(42):35172-83. doi: 10.1074/jbc.M505559200. Epub 2005 
      Aug 15.