Hsc62, Hsc56, and GrpE, the third Hsp70 chaperone system of Escherichia coli

Kazuaki Yoshimune, Tohru Yoshimura, Toru Nakayama, Tokuzo Nishino, Nobuyoshi Esaki

Research output: Contribution to journalArticlepeer-review

27 Citations (Scopus)


Hsc62 is the third Hsp70 homolog of Escherichia coli, which we found previously. Hsc62 is structurally and biochemically similar to DnaK, but hscC gene encoding Hsc62 did not compensate for the defects in the dnaK-null mutant of E. coli MC4100 strain. We cloned the ybeV gene and purified the gene product named Hsc56, a 55, 687-Da protein with a J-domain like sequence. Hsc56 stimulated the ATPase activity of only Hsc62 but not those of the other Hsp70 homologs, DnaK and Hsc66. Hsc56 contains the -His-Pro-Glu- sequence corresponding to the His-Pro-Asp motif in DnaJ, which is indispensable for DnaJ to interact with DnaK. Conversion of -His-Pro-Glu- to -Ala-Ala-Ala- abolished the ability of Hsc56 to stimulate the ATPase activity of Hsc62. GrpE, a nucleotide exchange factor for DnaK, also stimulated the ATPase activity of Hsc62 in the presence of Hsc56. Hsc62-Hsc56-GrpE is probably a new Hsp70 chaperone system of E. coli.

Original languageEnglish
Pages (from-to)1389-1395
Number of pages7
JournalBiochemical and Biophysical Research Communications
Issue number5
Publication statusPublished - 2002


  • DnaJ
  • DnaK
  • GrpE
  • Hsc56
  • Hsc62
  • Molecular chaperone


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