Recognizability of heterologous co-chaperones with Streptococcus intermedius DnaK and Escherichia coli DnaK

Streptococcus intermedius DnaK complements the temperature-sensitive phenotype of an Escherichia coli dnaK null mutant, only if co-chaperones DnaJ and GrpE are co-expressed. Therefore, we examined whether S. intermedius DnaK and E. coli DnaK could recognize heterologous co-chaperones in vitro. The addition of heterologous GrpE to DnaK and DnaJ partially stimulated ATPase activity, and almost completely stimulated the luciferase refolding activity. Addition of heterologous DnaJ to GrpE and DnaK also stimulated ATPase activity but significant luciferase refolding activity was not observed. Moreover, E. coli DnaJ had a negative effect on the luciferase refolding activity of the S. intermedius DnaK chaperone system. In E. coli chaperone mutants, with the exception of E. coli DnaJ higher expression of the heterologous co-chaperones partially or almost completely complemented the temperature-sensitive-phenotype. These results indicated that all heterologous co-chaperones could at least partially recognize DnaK of a distantly related species. A region of the ATPase domain that is present in the DnaK of gram-negative bacteria is absent in the DnaK of gram-positive bacteria. This region is believed to be important for the recognition of co-chaperones from gram-negative bacteria. However, insertion of this segment into the S. intermedius DnaK failed to increase its ability to recognize E. coli co-chaperones. This implied that this region might be unnecessary or insufficient for the recognition of E. coli co-chaperones. Therefore, our data suggested that a basic structural similarity is conserved among the components of the S. intermedius and E. coli DnaK chaperone systems, which allow weak associations between heterologous components.

This is the peer reviewed version of the following article: Tomoyasu, T., Tsuruno, K., Tanatsugu, R., Miyazaki, A., Kondo, H., Tabata, A., Whiley, R.A., Sonomoto, K. and Nagamune, H. (2018), Recognizability of heterologous co-chaperones with Streptococcus intermedius DnaK and Escherichia coli DnaK. Microbiol Immunol, 62: 681-693., which has been published in final form at https://doi.org/10.1111/1348-0421.12651. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. This article may not be enhanced, enriched or otherwise transformed into a derivative work, without express permission from Wiley or by statutory rights under applicable legislation. Copyright notices must not be removed, obscured or modified. The article must be linked to Wiley’s version of record on Wiley Online Library and any embedding, framing or otherwise making available the article or pages thereof by third parties from platforms, services and websites other than Wiley Online Library must be prohibited.