Related Experiment Video
Updated: Oct 15, 2026

Escherichia coli -Based Complementation Assay to Study the Chaperone Function of Heat Shock Protein 70
Published on: March 8, 2024
Comparison of low-molecular-weight heat stress proteins encoded on plasmids in different strains of Streptococcus
1Eastern Regional Research Center, Agricultural Research Service, US Department of Agriculture, 600 East Mermaid Lane, Wyndmoor, PA 19038, USA.
Abstract:
Streptococcus thermophilus is used extensively for industrial fermentation of dairy products. Some strains of S. thermophilus are known to carry plasmids, and many of these plasmids are suspected of encoding low-molecular-weight heat stress proteins (Hsps) that may aid in survival under stressful conditions. In order to confirm the presence and examine the similarity of these low-molecular-weight Hsps, genes were identified and sequenced encoding Hsps on plasmids pER16 (4.5 kb), pER35 (10 kb), and pER36 (3.7 kb) from three different strains of S. thermophilus. The plasmid replication proteins were also sequenced to examine their relatedness. Amino acid sequence comparisons of the Hsps and of the replication proteins revealed a high degree of identity suggesting a common origin. Heat stress proteins enhance the viability of bacteria in extreme environments, and the presence of an Hsp encoded on a plasmid may enhance survival of S. thermophilus under harsh production conditions.
Related Concept Videos
Other Stress Responses in Bacteria
Diversity of Archaea III
Diversity of Archaea IV
Plasmids
Stringent Response in E. coli
Modern Molecular Taxonomy

