Discovery of a ptsHI operon, which includes a third gene (ptsT), in the thermophile Bacillus stearothermophilus | JoVE Visualize

Discovery of a ptsHI operon, which includes a third gene (ptsT), in the thermophile Bacillus stearothermophilus

Xiaokuang Lai¹, Lonnie O Ingram¹

¹Department of Microbiology and Cell Science, IFAS, University of Florida, Gainesville, FL 32611, USA.

Microbiology (Reading, England)|June 1, 1995

View abstract on PubMed

Summary

The Bacillus stearothermophilus ptsHI operon encodes proteins for cellobiose uptake via the phosphoenolpyruvate-dependent phosphotransferase system (PTS). A novel gene, ptsT, within this operon, exhibits unique properties and growth inhibition in E. coli mutants.

Area of Science:

Microbiology
Molecular Biology
Biochemistry

Background:

The thermophilic bacterium Bacillus stearothermophilus possesses genes for cellobiose uptake via the phosphoenolpyruvate-dependent phosphotransferase system (PTS).
Previous work identified a cel operon in this organism.

Purpose of the Study:

To clone and sequence the ptsHI operon in B. stearothermophilus.
To characterize the function and properties of the encoded proteins, including a novel gene ptsT.

Main Methods:

Gene cloning and sequencing of the ptsHI operon.
Expression of B. stearothermophilus ptsH and ptsI genes in Escherichia coli.
Complementation analysis of E. coli host mutations.
Bioinformatic analysis of translated protein sequences.
Growth inhibition assays in E. coli.

Main Results:

The ptsHI operon was cloned and sequenced, revealing genes for HPr (ptsH) and Enzyme I (ptsI) of the PTS.
A third gene, ptsT, of unknown function was identified within the operon.
B. stearothermophilus PTS proteins showed higher predicted pI and different amino acid composition compared to mesophilic homologs.
ptsT inhibited the growth of E. coli ptsI mutants at 37°C but not at 30°C.
The ptsT product has characteristics of bacterial histone-like proteins but lacks database homology.

Conclusions:

B. stearothermophilus contains a complete PTS for cellobiose uptake.
The ptsHI operon, including the novel ptsT gene, plays a role in this process.
The unique properties of B. stearothermophilus PTS proteins and the function of ptsT warrant further investigation.