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Sequence analysis of the Legionella micdadei groELS operon
P Hindersson1, N Høiby, J Bangsborg
1Department of Clinical Microbiology 8223, University of Copenhagen, Institute of Medical Microbiology, Denmark.
FEMS Microbiology Letters
|January 1, 1991
Summary
Legionella micdadei heat shock protein GroEL and GroES genes were sequenced, revealing conserved heat shock expression signals. However, heat shock did not increase GroEL protein levels in L. micdadei or recombinant E. coli.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Legionella micdadei is a significant pathogen.
- Heat shock proteins (HSPs) play crucial roles in cellular stress response.
- Understanding HSP regulation in L. micdadei can provide insights into bacterial survival mechanisms.
Purpose of the Study:
- To sequence the DNA fragment encoding the common antigen and a 13 kDa protein of Legionella micdadei.
- To identify and characterize the heat shock protein genes GroEL and GroES in L. micdadei.
- To investigate the expression and regulation of L. micdadei GroEL under heat shock conditions.
Main Methods:
- DNA sequencing of a 2.7 kb fragment from L. micdadei.
- Identification of open reading frames (ORFs) corresponding to GroEL and GroES.
- Bioinformatic analysis of upstream regulatory sequences, including heat shock signals and a poly-T region.
- Western blot analysis using an L. micdadei specific anti-GroEL antibody to assess protein levels during heat shock in both native and recombinant systems.
Main Results:
- A 2.7 kb DNA fragment of L. micdadei was sequenced, revealing two ORFs encoding proteins of 57,677 Da (GroEL) and 10,456 Da (GroES).
- Conserved heat shock expression signals (-35, -10, Shine-Dalgarno) and a poly-T region, similar to the Escherichia coli groELS operon, were identified upstream of the L. micdadei groEL gene.
- Western blot analysis showed no significant increase in GroEL protein levels during heat shock in L. micdadei or in recombinant E. coli expressing L. micdadei GroEL, despite conserved regulatory sequences.
Conclusions:
- The L. micdadei groEL and groES genes share significant homology with their E. coli counterparts, including regulatory elements.
- The absence of GroEL protein induction during heat shock suggests post-transcriptional or post-translational regulatory mechanisms may be involved in L. micdadei's heat shock response.
- Further research is needed to elucidate the precise regulation of heat shock proteins in Legionella species.